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Breaker of Armies: Air Power in the Easter Offensive and the Myth of Linebacker I and II

Phil Haun and Colin Jackson

Abstract: Most traditional accounts identify the Linebacker I and Linebacker II campaigns as the most effective and consequential uses of U.S. air power in the Vietnam War. They argue that deep interdiction in North Vietnam played a central role in the defeat of the Easter Offensive and that subsequent strategic attacks on Hanoi forced the North Vietnamese to accept the Paris Accords. We find that these conclusions are false. The Linebacker campaigns were rather ineffective in either stopping the Communist offensive or compelling concessions. The most effective and consequential use of U.S. air power came in the form of close air support and battlefield air interdiction directly attacking the North Vietnamese Army in South Vietnam. The success of these air strikes hinged on the presence of a U.S.-operated, tactical air control system that incorporated small numbers of ground advisors, air liaison officers, and forward air controllers. This system, combined with abundant U.S. aircraft and a reasonably effective allied army, was the key to breaking the Easter Offensive and compelling Hanoi to agree to the Paris Accords. The effectiveness of CAS and BAI and the failure of interdiction and strategic attack in the Vietnam War have important implications for the use of air power and advisors in contemporary conflicts in Iraq, Syria, and Afghanistan.

Most accounts of U.S. air power in the latter phases of the Vietnam War revolve around the Linebacker I and II campaigns of 1972.1 While scholars offer a range of explanations for the success of these campaigns, the U.S. Air Force has long seen them as proof of the politically decisive effects of interdiction and strategic attack. The widely held belief that these independent air operations on North Vietnam coerced Hanoi to sign the Paris Peace Accords is wrong.2 It was, rather, the defeat of the North Vietnamese

Army (NVA) during the Easter [Nguyen-Hue] Offensive in South Vietnam that convinced the North to accept a peace agreement in October of 1972. U.S. air power was decisive,

1 Robert Pape, Bombing to Win (Ithaca NY: Cornell University Press, 1996); Mark Clodfelter, The Limits of Air Power: The American Bombing of North Vietnam (Lincoln, Nebraska: University of Nebraska Press, 1989); Stephen Randolph, Powerful and Brutal Weapons (Cambridge MA: Harvard University Press, 2007); Marshall Michel, The Eleven Days of Christmas (San Francisco: Encounter Books, 2002). 2 Henry Kissinger, The White House Years (New York: Simon and Schuster, 1979), 1303; John Vogt, “Speech Delivered to Air Force Association, Honolulu, HI, 15 November, 1973,” AFHRA K168.06-234 73/11/15-73/12/04, 17; Clodfelter, 167-8; Robert Pape, “Coercive Air Power in the Vietnam War,” International Security 15:2 (Fall, 1990), 105.

1 DRAFT: DO NOT CITE WITHOUT PERMISSION not with deep interdiction or strategic air strikes, but by stopping the NVA’s blitzkrieg in the South and breaking its army in the process.

U.S. air power proved most effective in the role of close air support (CAS) and battlefield air interdiction (BAI), using tactical fighter-bomber aircraft (tacair), ground radar controlled B-52 Arc Light strikes, and fixed- and rotary-wing gunships to attack

NVA conventional formations. While the aircraft platforms and weapons were important, it was the system of U.S. targeting and fire control that was the critical factor in the

U.S./South Vietnamese victory in the South. A small cadre of Army ground advisors and

Air Force liaison officers used the tactical air control system (TACS) to provide the targeting information, coordination, and final strike control for successful air operations.

Where the TACS was present, U.S. air power and South Vietnamese troops formed an effective combined arms team, blunting the NVA attacks near Saigon and in the Central

Highlands. By contrast, in Quang Tri province, where the U.S. TACS was transferred to

Vietnamese control, the lack of effective coordination resulted in the collapse of the South

Vietnamese Army of the Republic of Vietnam (ARVN) along the demilitarized zone

(DMZ). The subsequent reintroduction of an American TACS, the replacement of the

South Vietnamese commander, and hard fighting on the part of the ARVN culminated in the recapture of Quang Tri City and the final collapse of the Communists’ Easter

Offensive. In the fall of 1972, with its army crippled and its forces falling back on all fronts, Hanoi opted to pursue a peace deal with the United States.

In addition to CAS and BAI, in the second month of the Easter Offensive, the U.S. launched the heralded Linebacker I air interdiction campaign to disable North Vietnamese railroad lines and halt the flow of supplies to the south. By that time, however, the NVA

2 DRAFT: DO NOT CITE WITHOUT PERMISSION had already deployed its heavily armored divisions and had stockpiled sufficient supplies and ammunition to wage a multi-month blitzkrieg in the south. As a result, Linebacker I did not play a significant role in the defeat of the NVA in the Easter Offensive, nor did it play a major, independent role in compelling the North Vietnamese to seek a diplomatic agreement.

The persistence of the Linebacker myth and the neglect of the role of CAS and

BAI in the Easter Offensive have their roots in service politics. For the U.S. Air Force,

Linebacker I and II were the exorcism of the political constraints of Rolling Thunder and a validation of precision attack on strategic targets. The Air Force had little institutional interest in telling the story of how independent air operations in North Vietnam failed in

Linebacker I or how Linebacker II succeeded only in bringing the North Vietnamese back to Paris to sign an agreement to which they had previously agreed. They had even less incentive to acknowledge the decisive impact of CAS and BAI missions in the South as they represented a subordination of air assets to ground commanders. Similarly, the Army had little to gain by highlighting how the largest battle of the Vietnam War was won, not by U.S. combat troops, but by a weak ally supported by a handful of military advisors and air liaison officers who coordinated the firepower of the Air Force and Navy to tip the scales against the more powerful opponent.

This reexamination of the air offensives of 1972 has a direct bearing on the contemporary debates over U.S. air power and its integration with ground forces. First, it shifts the debate from the general efficacy of air power to an evaluation of rival uses of air power. The experience of the Easter Offensive suggests that direct attack on conventional armies is more effective than interdiction and strategic attack. By contrast, the history of

3 DRAFT: DO NOT CITE WITHOUT PERMISSION the 1972 air campaigns undercuts claims that Linebacker I and II are examples of decisive air campaigns independent of friendly ground forces. Second, this case highlights the primacy of the air control system and missions over the aircraft and weapons involved.

Having a system to integrate U.S. air power into a friendly ground force’s scheme of operations is as important as the specialized platforms, sensors and precision weapons employed to seek out and destroy enemy armies. Third, the key ingredient in the air control system is the small cadre of trained ground advisors, air liaison officers, observers, and controllers. The history of the Easter Offensive suggests that a sufficient number of skilled personnel, supported by a moderately capable client army, can stop and even roll back large-scale conventional invasions. While much has changed in weapons technology since 1972, the primacy of the air control system and the importance of small numbers of skilled air and ground controllers have not. The experience of 1972 strongly suggests that the presence of ground advisors and air liaison officers in a U.S.-run TACS can make the difference in the effective use of U.S. air power alongside allied ground forces. These findings have direct bearing on the contemporary debates over the significance, scale and efficacy of U.S. air power employment and advisory support across a range of theaters including Afghanistan, Libya, Yemen, Syria, Iraq, and Ukraine.

The Vietnam Air Power Debate

Four decades after the Vietnam War, debate still surrounds the role air power played in convincing Hanoi to sign a peace agreement in January of 1973. Three schools of thought have emerged over why air power proved effective in 1972, when it had failed up until that point. U.S. Air Force and Navy officers who commanded the air operations in Vietnam during the Rolling Thunder campaign of 1965 to 1968 claim that the political

4 DRAFT: DO NOT CITE WITHOUT PERMISSION constraints imposed by President Johnson were responsible for the failure of the campaign.3 In 1972, by contrast, détente allowed Nixon to bomb Hanoi without the fear of escalation.

Air power historian Mark Clodfelter argues that the decisive factor was the decrease in U.S. political objectives following the Tet Offensive of 1968.4 In 1965, the

United States demanded Hanoi curtail its support of the Viet Cong (VC) insurgency. Such a concession, however, would have forced Hanoi to abandon its aspirations for a reunited

Vietnam under communist control. By contrast, Nixon sought a more modest policy objective of “peace with honor,” a ceasefire which withdrew U.S. forces while leaving the

NVA in the South. Such a peace deal significantly shifted the balance of power in

Hanoi’s favor and set the conditions for the eventual fall of Saigon in April 1975.

A third argument posed by air power theorist Robert Pape focuses on the differences in targeting between the Rolling Thunder and the Linebacker campaigns.5

Pape contends that Rolling Thunder failed because air strikes on North Vietnam’s industrial infrastructure could not inflict sufficient pressure to convince Hanoi to abandon its goal of reunification. Likewise, both Clodfelter and Pape note that Rolling Thunder failed to interdict supplies to the NVA and VC fighters in the South because of the minimal supply requirements for their guerilla operations. By 1972, however, the NVA had transformed into a conventional army dependent on supply lines that were then vulnerable to air attack.6

3 Admiral U.S. Sharp, Strategy for Defeat: Vietnam in Retrospect (Novato, CA: Presidio, 1978); General William Momyer, Airpower in Three Wars (Montgomery, AL: Air University Press, 2003) 4 Clodfelter, 148. 5 Pape, Bombing to Win, 176. 6 Clodfelter, 173; Pape, 200.

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Common to all three arguments is the assumption that the Linebacker I and II air campaigns in North Vietnam played a central role in Hanoi’s decision to seek a peace deal, an assumption that is fundamentally wrong.7 Recent scholarship on North

Vietnamese decision making and the author’s access to previously classified internal Air

Force assessments support an alternative interpretation of air power’s effectiveness as that of directly attacking the NVA and defeating them in the Easter Offensive.8 In order to make this argument, this article proceeds in four parts. The first section reviews air power and coercion theory and the causal logic underpinning the United States’ punishment and denial coercive strategies employed during the Vietnam War. Also examined are U.S. air power doctrine and the distinction between attacking enemy armies directly with close air support (CAS) and battlefield air interdiction (BAI), and the indirect approach of air interdiction. In addition, specific air power technologies employed for CAS and BAI are reviewed: tacair, B-52 Arc Light, and fixed- and rotary- wing gunships The second section evaluates the impact of air power on the three major battles of the Easter offensive: the fall of Quang Tri, the defense of An Loc, and the defense of Kontum. The outcomes of all three battles were determined before Linebacker I could have had an impact on the battlefield. This isolates the effect of CAS and BAI on the North Vietnamese deployed forces. The third section evaluates Linebacker I and the impact it had on North Vietnam’s resupply of the NVA fighting in South Vietnam. The final section assesses the role of air power in the retaking of Quang Tri which directly led to Hanoi seeking a diplomatic

7 Sharp, 248; Clodfelter, 167; Pape 199. 8 Recent research includes Nguyen, Hanoi’s War; Randolph, Powerful and Brutal Weapons; Huyen, “Defeating the Americans”; Ha Dang, ed., Collected Party Documents translated by Merle Pribbenow (Hanoi: National Political Publishing House, 2004). U.S. Air Force reports declassified in October 2013 by the authors include HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831; HQ Seventh Air Force Commanders’ Conference 18-19 July 1972 AFHRA K168.06-228 72/07/18-72/07/19; HQ Seventh Air Force History of Seventh Air Force 1 July 1972 – 29 March 1973, Volume I AFHRA740.01-25 1 July 72 – 29 Mar 73, v1.

6 DRAFT: DO NOT CITE WITHOUT PERMISSION solution in October 1972.9 Also considered is the diplomatic maneuvering that delayed a settlement and the impact Linebacker II had on the final agreement.

Coercion Theory and Air Power Doctrine

During the Vietnam War, the United States employed air power in an effort to compel Hanoi to alter its policies towards South Vietnam. Coercion threatens force or uses restricted force to convince an enemy to do one’s will.10 In On War, Carl Von

Clausewitz acknowledges coercion as an alternative to a brute force strategy, under which disarming the enemy can “be replaced by two other grounds for making peace: the first is the improbability of victory; the second is its unacceptable costs.”11 This insight forms the basis for modern coercion theory, whereby making victory improbable is known as a denial strategy and making costs unacceptable as a punishment strategy.12 In regard to punishment, Thomas Shelling argues such a strategy works by imposing high expected costs upon the target by “…the threat of damage, or of more damage to come.”13 A successful punishment strategy signals the credible threat of future costs in order to convince the enemy to concede now.

The Rolling Thunder air campaign in 1965 started as a punishment strategy known as gradual escalation. The Johnson administration intended to take hostage targets highly prized by Hanoi. Instead of attacking these sites, Johnson ordered strikes on military and transportation targets along North Vietnam’s panhandle south of the 19th parallel.14 When the air raids had compelled Hanoi neither to negotiate nor to withdraw support for the VC,

9 Nguyen, 270; Randolph, 325; Huyen, “Defeating the Americans.” 10 Carl Von Clausewitz, On War (Princeton: Princeton University Press, 1976), 77. 11 Ibid., 91. 12 Glenn Snyder, Deterrence by Denial and Punishment, Center of International Studies Research Monograph No.1, (Princeton: Princeton University, 1958). 13 Thomas Schelling, Arms and Influence (New Haven: Yale University Press, 1966), 3. 14 HQ PACAF (1966) CHECO Report, Rolling Thunder Mar-June 1965, 13a.

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Johnson approved additional bombing up to the 20th parallel. Upon the failure of these attacks, he ordered air strikes still further north.15 In the end, five months of restricted air strikes failed to compel Hanoi to forsake its goal of reunification. As a result, the United

States abandoned gradual escalation in favor of a denial strategy based on air interdiction.

Coercion by denial is an alternative to coercion by punishment.16 Whereas punishment increases the costs an enemy expects to suffer, denial decreases an enemy’s expected benefits for continuing to fight.17 A denial strategy succeeds by attacking the enemy’s military capability. If the enemy can be convinced that its military strategy will not work, that the situation is hopeless, then it has an incentive to concede and avoid additional costs of fighting.18 While punishment threatens what the enemy values, denial lowers the enemy’s probability of victory.

This was the goal when the United States adopted a denial strategy directly attacking the NVA during the Easter Offensive in March of 1972 and attacking North

Vietnamese supply lines in the Linebacker I air campaign beginning in May. Prior to evaluating and contrasting air power during these air operations, a brief review of U.S. Air

Force doctrine for attacking enemy armies is warranted. As a result of its experience in

World War II and Korea, by the Vietnam War the USAF had refined its Counterland doctrine to include interdiction and close air support.19 Airmen defined interdiction as

“…the application of air fire power for the purpose of neutralizing, destroying or

15 Ibid., 39a; HQ PACAF (1967) CHECO Report, Rolling Thunder Jul 65 – Dec 1966, Figure 2; For more on Rolling Thunder see Pape, 181-2. 16 Jonathan Shimshoni, Israel and Conventional Deterrence: Border Warfare from 1953 to 1970 (Ithaca NY: Cornell University Press, 1988), 6; Pape, 18-19. 17 Pape, 18. 18 Pape, 17. 19 Air Force Manual 1-7, Theater Air Forces in Counter Air, Interdiction, and Close Air Support, 1 March 1954.

8 DRAFT: DO NOT CITE WITHOUT PERMISSION harassing enemy surface forces, resources and lines of communication.”20 Air interdiction

(AI) missions indirectly attacked an enemy army by targeting its forces, LOCs, and supplies deep inside enemy territory. Battlefield air interdiction (BAI), by contrast, directly attacked the enemy’s fielded forces, LOCs, and supplies within the battle area. 21

The delineation between an AI and BAI mission was the bomb line.22 Beyond the bomb line, air commanders selected targets, while missions inside the bomb line required coordination with ground commanders. In addition to BAI, air power short of the bomb line could also be employed as close air support (CAS). CAS placed even more controls upon aviators than BAI as strikes required detailed coordination and clearance by the friendly ground commander operating in close proximity to enemy forces.

All of South Vietnam and Route Pack 1 just north of the DMZ fell within the bomb line.23 As such, U.S. air strikes within this territory were under the control of the

Military Assistance Commander Vietnam (MACV), U.S. Army General Creighton

Abrams, who had replaced General William Westmoreland by 1972.24

CAS and BAI: Tacair, B-52 Arc Light, and Gunships

The United States relied upon four air power technologies for BAI and CAS. First, tactical aircraft (tacair) included an assortment of fighter-bombers flown by the U.S. Air

20 Tactical Air Command Manual 55-3, Joint Air-Ground Operation, 15. 21 Terrance McCaffrey, What Happened to Battlefield Air Interdiction? (Montgomery, AL: Air University Press, 2004), 15; Air Force Doctrine Document 2-1.3, Counterland Operations, 11 September 2006, 25. The Air Force removed the term battlefield interdiction from its doctrine 1966. In the 1980s the AirLand Battle concept reintroduced the term battlefield air interdiction which is why the battlefield air interdiction and the acronym BAI is used in this article. The Air Force eliminated the term BAI from doctrine prior to the 1991 Gulf War. 22 The bomb line is now referred to as the fire support coordination line (FSCL). 23 For deconfliction the U.S. Air Force and Navy divided North Vietnam into 6 sections called Route Packs. Route Pack 1 was the most southern and Route Packs 5 and 6 the most northern next to the Chinese border. 24 HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401- 19720831, V-1-2. In June 1972 Abrams was appointed Chief of Staff of the Army and he was replaced by General Frederick C. Weyand.

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Force, Navy, Marine Corps and the South Vietnamese Air Force (VNAF).25 These fast jets carried an assortment of air-to-ground munitions.26 Tacair was most effective during the day and under visual flight conditions when aircrew could visually identify targets or be directed by forward air controllers (FACs) who located, identified and marked targets for them.27 Tacair proved lethal against tanks, artillery and concentrated troops in the open.

Tacair could operate in high threat environments where the North Vietnamese operated SA-2 surface-to-air radar-guided missiles and MiG air to air interceptors. As a result, tacair could be employed where B-52s, gunships, and airborne FACs could not, just north of the DMZ in Route Pack 1 and just south of it in Military Region I (MR I).28

Because of its survivability and versatility, tacair was also tasked with penetrating deep inside North Vietnam’s air defenses in the Rolling Thunder and Linebacker I and II air campaigns.

While tacair was most effective during the day, B-52 Arc Light missions offered distinct advantages for night and all-weather CAS and BAI. The B-52 arrived in

Southeast Asia in 1965. Vulnerable to SA-2s and MiG interceptors, the B-52s did not participate in the Rolling Thunder air strikes aimed deep into North Vietnam. General

25 These included A-4s, A-6s, A-7s, F-4s, F-100s, and F-105s. 26 Weapons included general purpose and laser-guided bombs, rockets, napalm, and cluster bombs. 27 Forward observers employed handheld lasers to guide precision bombs dropped by tacair against armor and artillery HQ Seventh Air Force, The U.S. Air War Against Tanks, AFHRA K740.041-2 20 May 1973, ii; HQ Seventh Air Force, US Air Forces vs The 130MM Field Gun April-November 1972, AFHRA K740.041- 1 Apr-Nov 1972, ii. During the Easter offensive the USAF reported 389 tanks destroyed and another 289 damaged from laser guided bomb strikes. HQ Seventh Air Force, The U.S. Air War Against Tanks, 28. 28 From 31 March 31 to 23 October 1972 the U.S. Air Force, Navy, Marine Corps and Vietnamese Air Force conducted over 18,000 strikes in Southeast Asia (North and South Vietnam, Cambodia and Laos), of which 94% were flown as CAS or BAI missions. 16,000 of these missions were flown south of the DMZ in South Vietnam, Laos and Cambodia, while another 1,000 were conducted just north of the DMZ in Route Pack 1 (RP 1). Still further north, another 1,250 missions were flown in the North Vietnamese panhandle in RP II, III and IV between the 18th and 20th parallel, and 360 strikes were conducted north of the 20th parallel, near Hanoi, Haiphong and the Chinese border. THOR DATABASE 31 March 1972 – 23 October 1972, courtesy of Jenns Robertson, USAF LtCol (ret).

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Westmoreland instead utilized the heavy bombers for BAI throughout South Vietnam and across the border into Laos, Cambodia and Route Pack 1.29 B-52 airstrikes packed a punch as a three-ship formation could spread up to three hundred and twenty 500-pound general purpose bombs over an area of one-by-two kilometers.30

By the Tet offensive, the B-52 Arc Light missions had proven lethal against concentrations of enemy troops in the open. Arc Light was the code name for missions flown under control by one of the five ground-based radars distributed throughout South

Vietnam and Thailand. By 1972, B-52 Arc Light missions had become accurate enough to employ within a kilometer of friendly positions, which made them capable of night and all weather CAS.31

A single B-52 bomb run could destroy most of the supplies and troops within its vast bomb pattern. While previously the NVA and VC had by tunneling been able to negate B-52 strikes, in the Easter offensive NVA units on the march were caught in the open, rendering them more vulnerable to air attack.

For all its capability, the B-52 did have limitations. First, air strikes were only as effective as the quality and timeliness of available intelligence. Second, the NVA reacted to B-52 strikes by dispersing troops and supplies to decrease the effectiveness of their strikes. This increased the survivability of troops but also made it more difficult for the

29 William Head, War from above the Clouds (Maxwell AFB, AL: Air University Press, 2002), 18, 29. 30 To increase the bomb load, the older B-52D models were modified to carry 108 conventional 500lb bombs. The B-52G models had internal fuel cells which increased range but, as a result, could carry only 27 conventional bombs, just double that of an F-4 load out. Head, 22. 31 From 31 March to 23 October 1972 B-52s flew 6,000 missions, 88% south of the DMZ, 10% in RP 1, and fewer than 2% north of RP 1. Missions consisted of three B-52 sorties. The missions in RP 1 occurred after July once SA-2s had been suppressed. Two sources on the B-52 missions have total missions between 5,600 – 6,600, the lower number coming from the THOR database from 31 March 1972 – 23 October 1972 and the higher figure from the HQ PACAF Summary Air Operations Southeast Asia volumes from April to October 1972 AFHRA K717.3063 April – Oct 1972.; HQ PACAF, Evaluation Report for the NVN Offensive (April- August 1972) AFHRA K717.04-9 19720401-19720831, VII-1. For additional details on the development of Arc Light tactics, see HQPACAF CHECO ARC LIGHT: June 1967-December 1968.

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NVA to concentrate in order to conduct offensive operations. Third, B-52 air strikes, while lethal against soft targets, were less so against armor and artillery.32 As such, the B-

52 was best suited for area targeting.

A third weapons system developed during the Vietnam War was the fixed-wing gunship. The USAF began by converting cargo planes into gunships, first with the AC-

47, then the AC-119, and finally the AC-130.33 These gunships took advantage of a unique operating method for which the pilot used a pylon turn to train a battery of laterally mounted guns on a specific target. The pylon turn enabled the pilot to adjust fires in close proximity to friendly forces.34 By 1972, over two dozen AC-119s and AC-130s operated in Southeast Asia.35 The AC-130 proved most effective against NVA conventional forces.36 The gunship was armed with a 40mm cannon and in early 1972, the first AC-130 was upgraded with a 105mm cannon, giving the aircraft an improved anti-armor capability. Its low-light television and infrared sensors combined with its digital fire control computer and inertial navigation system to make the AC-130 adept at night operations.37 From 1968 to 1972, during the Commando Hunt interdiction campaigns along the Ho Chi Minh Trail, the AC-130 earned a reputation as a truck killer. In the

Easter Offensive, during the battles of An Loc and Kontum, the gunship was relied upon for CAS as it could loiter for prolonged periods over friendly positions and provide

32 HQ MAC-V The Nguyen Hue Offensive MACDI Study 73-01 12 January 1973, 8. 33 For a detailed history of the development of fixed wing gunships, see Jack Ballard, Development and Employment of Fixed-Wing Gunships (Washington, D.C.: Office of Air Force History, 1982). 34 Ballard, 2. 35 Lavalle, Airpower and the 1972 Spring Invasion, (Washington, D.C.: Office of Air Force History, 1985) 30. 36 From April to June, AC-130s conducted 1,117 combat sorties in South Vietnam, Laos and Cambodia with 55% of the missions providing CAS for troops-in-contact situations. History of the 8th TAC Fighter Wing, v1 “Narrative”, AFHRA K-WG-8-H1 Apr-Jun 1972, v.1, 16, 18, 19. 37 HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401- 19720831, VI 2-3.

12 DRAFT: DO NOT CITE WITHOUT PERMISSION precise, around-the-clock firepower during the most critical days and nights of the battles.38 Though the AC-130 could safely operate above small arms fire, it was vulnerable to surface-to-air missiles and anti-aircraft artillery (AAA). The loss of an aircraft near the DMZ on 28 March 1972 prompted the gunships to we withdrawn from operations near Quang Tri.

The fourth weapon system developed by U.S. Army aviation entailed precision- guided weapons mounted on rotary-wing gunships. In 1972, the Army combined Tube- launched Optically-tracked Wire-guided (TOW) missiles aboard UH-1B Huey helicopters.

With the start of the Easter Offensive, the Army saw an opportunity to test the Huey gunship and on 24 April, two modified aircraft and three TOW systems arrived in Saigon.

The crews soon had the gunships operating in the Central Highlands at Kontum, where they proved lethal in a reduced threat environment without AAA or SA-7 infrared-guided surface-to-air missiles.39 The TOW mounted gunship had several distinct advantages. Its extended range of over 2,500 meters along with its weapons reliability and precision provided a potent tool for destroying armor and point targets.40

The next section evaluates how the U.S. employed these weapon systems in the three major offensives launched by the NVA at the outset of the Easter offensive.

Air Power in the Easter Offensive

In 1968, following the operational defeat of the NVA and VC in the Tet Offensive,

Hanoi began reconstituting its forces in the South. In response, the USAF conducted a

38 History of the 8th TAC Fighter Wing, v1 “Narrative”, AFHRA K-WG-8-H1 Apr-Jun 1972, v.1, 24. HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401- 19720831, VI-1. 39 Major John Burns, XM-26 TOW: The Birth of the Helicopter as a Tank Buster (Quantico: United States Marine Corps Command and Staff College, 1994), 15-17; In 41 days operating in MR II, the two Huey gunships reported destroying 47 targets including 24 tanks, Burns 75-77. 40 The UH-1B/Tow combination was 93% reliable and 82% hits of the reliable launches. Burns, 90.

13 DRAFT: DO NOT CITE WITHOUT PERMISSION series of seasonal air interdiction campaigns into Laos, known as Commando Hunt, with the objective of curbing the flow of men and supplies transiting the Ho Chi Minh Trail. In

1970, U.S. and ARVN (Army of the Republic of Vietnam) troops crossed into Cambodia to cut enemy LOCs to the port of Sihanoukville and deny sanctuary for NVA units threatening the southern Military Regions III (including Saigon) and IV (the Mekong

Delta) in South Vietnam.

The operational success of the joint U.S./ARVN operations in Cambodia encouraged U.S. commanders to propose a more ambitious ARVN ground offensive in

Laos to cut the Ho Chi Minh Trail.41 The resulting operation, Lam Son 719, was launched in late January 1971 to disrupt the NVA buildup adjacent to MR I in the western Quang

Tri province and prove the mettle of the ARVN.42 Unfortunately for U.S. military operations, the domestic blowback from the invasion of Cambodia had led to a legal prohibition on the employment of U.S. ground forces outside the Republic of Vietnam.

As a result, the 20,000 ARVN troops of the Lam Son 719 raid would enjoy ample U.S. air support but would advance without the direct support of U.S. combat troops or advisors.

While the first week of the operation was encouraging, the raid stalled as South Vietnam’s

President Thieu sought to limit ARVN casualties and the NVA concentrated over 60,000 troops to cut the ARVN salient into Laos.43 After 45 days in Laos, the ARVN units withdrew. For the ARVN, the results of Lam Son 719 were Pyrrhic at best; while they had managed to destroy numerous NVA stockpiles, the heavy losses and the mixed

41 Brig. Gen. Tran Dinh Tho, The Cambodian Incursion (Washington, D.C.: U.S. Army Center of Military History, 1979); James H. Willbanks, Abandoning Vietnam: How America Left and South Vietnam Lost its War (Lawrence: The University Press of Kansas, 2004), 83-86. 42 Robert Sander, Invasion of Laos 1971: Lam Son 719 (Norman: University of Oklahoma Press, 2014). 43 James H. Willbanks, A Raid Too Far: Operation Lam Son 719 and Vietnamization in Laos (College Station: Texas A&M Press, 2014), 168.

14 DRAFT: DO NOT CITE WITHOUT PERMISSION performance of the South Vietnamese units undermined ARVN morale and drew into question the efficacy of Vietnamization. Though the NVA lost over 20,000 troops to U.S. air power and ARVN firepower, the North Vietnamese emerged from the Laotian campaign emboldened.44

The North Vietnamese decision to launch the Easter Offensive in 1972 was a reaction to an array of opportunities and threats. The failure of Lam Son 719 suggested that a major conventional offensive against the ARVN might succeed. The steady withdrawal of U.S. ground forces meant that the ARVN would have to fend for itself.

Still, there were reasons for the North to fear that this window of opportunity might be closing. In the aftermath of the Tet offensive of 1968, the United States and their ARVN allies had been increasingly successful in suppressing VC resistance in the south. Nixon’s successful overtures to the Chinese and his pursuit of détente with both the Chinese and

Russians jeopardized North Vietnam’s ties with its two sponsors. Unless the North moved swiftly to topple its neighbor, it faced the prospect of a stronger Saigon and diminishing support from its Communist patrons.

Recent research on Communist decision making suggests that it was North

Vietnamese leaders Le Duan and Le Duc Tho who championed a major, conventional offensive to resolve these dilemmas. At a minimum, such an offensive would upset the

Nixon Administration’s progress in isolating the regime from its sponsors; at best it might break the ARVN and trigger the southern uprising the North had failed to achieve in

1968.45 Having decided on an invasion, the NVA’s next step was to translate these abstract goals into concrete military objectives. The destruction of large ARVN units and

44 Ibid., Willbanks, A Raid Too Far, 154, 162-163, 188. 45 Lien-Hang T. Nguyen, Hanoi’s War (Chapel Hill: The University of North Carolina Press, 2012), 232- 234.

15 DRAFT: DO NOT CITE WITHOUT PERMISSION the seizure of major cities and towns were seen as ways to shatter Vietnamization, strengthen the North’s hand in the Paris negotiations, and precipitate the collapse of the southern regime.46

To accomplish these sweeping goals, the North Vietnamese committed 14 of its 15 divisions and 26 separate regiments, a total of between 130,000 and 150,000 troops.

These units were equipped with new Soviet conventional equipment to include 1,200 tanks and armored fighting vehicles, long-range artillery, advanced air defense systems, and anti-tank guided missiles.47 The NVA forces would attack on three separate axes: the main attack across the DMZ in MR I, a second attack from Cambodia towards Saigon in

MR III, and a third attack from Laos and Cambodia into the Central Highlands of MR II

(See Map I).48 A breakthrough on any of these axes would be fatal; the wide distribution of these attacks forced the South Vietnamese to divide their attention and resources. On each of these axes the North Vietnamese planned to combine long range, heavy artillery preparations with the shock of tank attacks to shatter ARVN resistance and produce a breakthrough that could be exploited by its infantry and mechanized formations.49

46 Ibid., Willbanks, Abandoning Vietnam, 124-127; The Nguyen-Hue Offensive, MACDI Study 73-01, 12 January 1973, C-1. 47 Thomas P. McKenna, Kontum: The Battle to Save South Vietnam (Lexington: The University Press of Kentucky, 2011), 60-61; ibid., Willbanks, Abandoning Vietnam, 127. 48 For a discussion of North Vietnamese debates over the main effort, see Lien-Hang Nguyen, Hanoi’s War, 245. 49 Lam Quang Thi, The Twenty-five Year Century (Denton: University of North Texas Press, 2001), 266- 267; Jack S. Ballard, Development and Employment of Fixed Wing Gunships (Washington: Government Printing Office, 1982), 236.

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MAP 1: South Vietnam and the Easter Offensive50

On paper, the ARVN was a large, robustly equipped, and reasonably well-trained, army. On the eve of the invasion, the ARVN fielded 11 infantry divisions, 58 artillery

50http://www.westpoint.edu/history/SiteAssets/SitePages/Vietnam%20War/vietna m%20war%20map%2033.jpg accessed 30 Apr 2015.

17 DRAFT: DO NOT CITE WITHOUT PERMISSION battalions, and 19 armor battalions. The 550,000 men of the Regional Forces and Popular

Forces provided manpower for the defense of South Vietnam. This otherwise impressive force faced four problems. First, the removal of U.S. ground troops had led to an inevitable thinning of the defensive lines. In MR I, the target of the North Vietnamese main effort, 80,000 U.S. troops had been replaced by 25,000 ARVN troops holding much of the same ground.51 Second, the geography of South Vietnam gave the North

Vietnamese an opportunity to strike at multiple points from its sanctuaries and left the

ARVN with no easily defensible frontiers or strategic depth. Third, the quality of the

ARVN leadership varied widely; President Thieu’s struggle to maintain power and preserve the Republic of Vietnam led to countless political compromises that put political generals in critical positions. Fourth, the ARVN had been focused almost exclusively on counterinsurgency rather than conventional warfighting. While this had contributed to impressive gains in pacification between 1968 and 1972, it meant that the ARVN lacked experience in combined arms warfare.52

While the United States had removed almost all of its ground forces by late March

1972, the U.S. advisory command (MACV) and air forces remained in place. The senior

U.S. commander, General Creighton Abrams, recognized the North Vietnamese buildup in the fall of 1971. He correctly assessed that the attack would be a massive affair and the ultimate test of Vietnamization.53 Abrams’ plan was to use the North Vietnamese offensive as an opportunity to focus U.S. firepower and inflict overwhelming damage on

51 Lt. Gen. Ngo Quang Truong, The Easter Offensive of 1972 (Washington, D.C.: U.S. Army Center of Military History, 1977), 16. 52 Ibid., 166. 53 Lewis Sorley (ed.), Vietnam Chronicles: The Abrams Tapes (1968-1972) (Lubbock: Texas Tech University Press, 2004), 729, 733-734, 740-741, 745-56, 775, 803.

18 DRAFT: DO NOT CITE WITHOUT PERMISSION the North.54 The records of Abrams’ staff meetings in late 1971 and early 1972 reveal a clear anticipation of the centrality of U.S. air power and particularly the power of B-52

Arc Light missions inside South Vietnam. He was equally adamant that such fires be targeted by U.S. advisors or Forward Air Controllers (FACs):

“You know, air is really very good if you’ve got a way of putting it on the enemy, and it’s always really tied down to that – some guy out there that can see them, or knows where they are, and if he’s got communications to a FAC, you’re in business. And if you haven’t got that, if you haven’t got that, you’re going to wind up bombing trees.”55

Stripped of U.S. ground forces, Abrams planned to use the B-52s as his mobile reserve and the U.S. advisors as his eyes to break the impending North Vietnamese onslaught.56

Commando Hunt VIII, conducted over the winter of 1971-72 did not stop the deployment of enemy forces but did delay the NVA’s timetable. As a result, Hanoi slipped the start date for invasion until the end of March and, in order to take advantage of shorter supply lines, shifted the primary front from MR III near Saigon, to MR I next to the DMZ.57

The following section evaluates the impact U.S. air power had on the outcomes of the three major battles which occurred at the onset of the Easter offensive: the fall of

Quang Tri near the DMZ, the defense of An Loc near Saigon, and the defense of Kontum in the Central Highlands. These battles were decided before the Linebacker I air interdiction campaign could have had an impact on their outcomes. As such, the effects of air power were limited to direct attacks by CAS and BAI on the NVA’s fielded forces. At

An Loc and Kontum, U.S. air power played a key role in stopping the NVA’s offensive

54 Ibid., 568, 779, 782. 55 Ibid., 784. 56 Ibid., 782, 807. 57 Truong, 13.

19 DRAFT: DO NOT CITE WITHOUT PERMISSION and destroying large portions of the Communist army. The fall of Quang Tri, however, is the story of the failure of U.S. air power to stop the NVA advance.

The Battle in the North: MR I and the Fall of Quang Tri

On 30 March, 1972, the Communist offensive in MR I opened with a massive artillery preparation aimed at ARVN positions south of the DMZ. The ARVN forces were spread across a series of firebases originally established by the Americans to support the counterinsurgency and stave off attacks from the Laotian sanctuaries to the west.58 Taking advantage of the longer range of their artillery, the NVA fired over 5,000 rounds of artillery and rocket fire in the first 24 hours of the attack.59 These fires largely silenced the ARVN artillery arrayed across the 12 northern firebases, allowing NVA infantry forces to encircle those isolated posts. The 40,000 troops of the 304th and 308th divisions and three separate infantry regiments, supported by 200 tanks, enveloped the ARVN front line positions from the north and the west.60

The defenders in MR I were unprepared for an assault of this scale and intensity.

The guardian of the northern defenses was the newly formed ARVN 3rd Division, numbering roughly 11,000 men.61 Before the offensive, the ARVN command had been confident that their artillery and U.S. air power would be sufficient to defeat any assaults launched across the open terrain south of the DMZ.62 While this was plausible, the 3rd

Division had no detailed defensive plan to respond to such a conventional invasion.63 To

58 Ibid., Lam Quang Thi, 267; ibid., McKenna, 64. 59 Col. G.H. Turley, The Easter Offensive: Vietnam, 1972 (Novato: Presidio Press, 1985), 46-47, 65; ibid., McKenna, 63. 60 Ibid., Willbanks, Abandoning Vietnam, 127. 61 Ibid., Turley, 23. 62 Ibid., Turley, 29; ibid., Truong, 22-23. 63 Ibid., Turley, 50; ibid., Truong, 20.

20 DRAFT: DO NOT CITE WITHOUT PERMISSION make matters worse, the division had ignored specific invasion warnings from its own

Joint General Staff and was instead engaged in a rotation of two of its three regiments on the day of the North Vietnamese attack.64

A successful forward defense would have required the timely application of overwhelming artillery and air power and robust ARVN resistance on the ground. For several reasons, neither of these came to pass. First, the NVA artillery attack destroyed or silenced the ARVN artillery; without the use of their artillery, the ARVN were unable to defend the firebases, fire on the attacking columns, or suppress the NVA artillery.

Second, bad weather prevented the use of any significant tactical air support in the first week. During this critical period, the only sources of fires were [unobserved and radar controlled] B-52 Arc Light missions and naval gunfire from U.S. destroyers offshore.

Third, the Communists had moved substantial air defenses including SA-2 radar-guided missiles into the forward area; these defenses led to the withdrawal of vulnerable U.S. and

Vietnamese aircraft to include fixed-wing gunships. And finally, as part of the

Vietnamization process, the United States had removed its Tactical Air Control System

(TACS) from MR I. For the first month of the invasion, difficulties in coordinating observers, aircraft, and artillery severely limited the effectiveness of U.S. and ARVN firepower employed in the north.

Under such adverse conditions, the forward ARVN line began to crumble on the second and third days of the offensive.65 Once the line of forward fire bases had been breached, the ARVN scrambled to establish a defensive line along the Cua Viet river anchored around the town of Dong Ha north and west of Quang Tri City. North

64 Ibid., Turley, 30. 65 Ibid., Turley, 73.

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Vietnamese difficulties in coordinating their armored assault and delays in moving their own artillery forward led to a temporary pause in the Communist advance. General Lam, the senior ARVN commander in the north, took this as an opportunity to launch a counteroffensive on April 14, Operation Quang Trung 729. Unfortunately, Lam lacked the reserves, air power, and coordination to make any substantial advance against the numerically superior NVA forces; instead, the offensive further weakened the 3rd

Division’s defenses and set the stage for the final ARVN collapse in Quang Tri province.66

On April 27, the NVA renewed their attack with another massive artillery barrage followed by a tank attack. Once again, weather severely limited the effectiveness of U.S. and South Vietnamese tactical air support. The ARVN were driven back from the Cua

Viet river and were encircled in the provincial capital of Quang Tri. A flurry of contradictory orders from General Lam first to withdraw and then to hold in place contributed to the disintegration of the defenses of Quang Tri and a pell-mell retreat towards Hue. By May 2, the ARVN 3rd Division had been destroyed and the entire province of Quang Tri was in Communist hands.67

The collapse at Quang Tri led General Abrams to intercede with President Thieu and demand the removal of General Lam and his replacement by Lieutenant General

Truong.68 Truong’s prompt moves to prepare a new defensive line along the My Chanh

River north of Hue and the A Shau valley in the west marked the end of the Communist advance in MR I.69 The ARVN losses during the month of withdrawal had been severe.

In addition to the disintegration of the 3rd Division, the South Vietnamese had suffered

66 Dale Andrade, America’s Last Vietnam Battle: Halting Hanoi’s 1972 Easter Offensive (Lawrence: University Press of Kansas, 2001), 106; ibid., Truong, 36-37. 67 Ibid., Andrade, 145. 68 Ibid., Andrade, 141-142. 69 Ibid., Lam Quang Thi, 279; ibid., Willbanks, Abandoning Vietnam, 149.

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50% casualties in its ranger units and had lost 140 artillery pieces and over 200 armored vehicles.70

Air Power and the Fall of Quang Tri

The South Vietnamese Air Force (VNAF) maintained a fleet of light, fixed-wing, propeller-driven, O-1 forward observation aircraft, along with A-1 and A-37 attack aircraft to provide CAS and BAI for MR I. The VNAF was quickly overwhelmed, however, by the magnitude of the NVA’s offensive and the lethality of its air defenses. As a result, the

ARVN relied on U.S. air support. At the outset of the invasion, the USAF had over 180 forward air controllers (FACs), 200 tactical aircraft (tacair), 23 fixed-wing gunships, and thirty B-52 bombers deployed to South Vietnam, Thailand, and Guam.71 In April and

May of 1972, additional deployments brought the number of Air Force and Marine Corps tacair up to 417 fighter-bombers and 171 B-52s.72 In addition, the U.S. Navy deployed

180 tacair aboard two carriers in the Gulf of Tonkin. This number doubled in early April with the addition of two more carriers and a total of six carriers were available by early

June.73 The U.S. air order of battle by May totaled over 600 tacair, 171 B-52s, and 28 fixed-wing gunships, a force sufficient to provide air support for Quang Tri, An Loc, and

Kontum.74

70 Ibid., Truong, 61. 71 Lavalle, 39; HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04- 9 19720401-19720831, III-7, IV-1. 72 HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, AFHRA K740.04- 24 72/05/10-72/10/23, Figure 3; HQPACAF Summary Air Operations in Southeast Asia, Volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7. 73In June the Saratoga and Midway increased the total to 6 carriers. John Sherwood, Nixon’s Trident: Naval Power in Southeast Asia, 1968-1972 (Washington, D.C.: Naval History & Heritage Command, 2009), 36. Peter Mersky and Norman Polmar, The Naval Air War in VIETNAM, 2nd Edition (Baltimore: Nautical and Aviation Publishing Co of America, 1986), 195,197. 74 HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, AFHRA K740.04- 24 72/05/10-72/10/23, Figure 3; HQPACAF Summary Air Operations in Southeast Asia, Volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7.

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Even the influx of tacair, B-52s, and gunships with the resultant increase in CAS and BAI sorties could not prevent the fall of Quang Tri during the early stage of the Easter

Offensive. This was primarily due to three reasons: bad flying weather in MR I, NVA air defenses deployed along the DMZ, and an ineffective VNAF tactical air control system

(TACS). First, the NVA timed the invasion to take advantage of poor visibility and low cloud ceilings. This adversely affected the employment of tacair and gunships. The local weather in Quang Tri during the first two weeks of the offensive was particularly harsh with continuous heavy rain and cloud cover. Conditions near the DMZ were far worse than further south in MR II and III.75 The NVA concentrated and maneuvered its armor and troops with immunity across territory otherwise vulnerable to air attack. All-weather

B-52 Arc Light strikes were employed to some effect but were hampered by the lack of accurate and timely coordinates. U.S. naval gunfire was also used against targets near the coast, but its effectiveness was hampered by the poor weather that precluded the adjustment of fires by forward observers. By the time the weather improved in mid-April, the impact of additional air attacks on the NVA assault proved to be too little, too late.

Second, the NVA significantly increased the surface-to-air threat in MR I by relocating SA-2 radar-guided missiles near and, in some cases, across the DMZ and by deploying large numbers of medium and heavy anti-aircraft artillery (AAA). During the first weeks of the invasion, the NVA fired 1,000 SA-2 missiles near the DMZ.76 As a result, fixed-wing gunships could no longer operate near Quang Tri. The threat environment also proved lethal for low and slow flying FACs, now unable to effectively

75 PACAF Summary Air Operations Southeast Asia volume XCIII April 1972, AFHRA K717.3063 April 1972, 6-2; Truong, 38. 76 8th Tactical Fighter Wing, History of the 8th TAC Fighter Wing, 1 April through 30 June 1972, Supporting Documents AFHRA K-WG-8-HI Apr-Jun 1972, V.2.

24 DRAFT: DO NOT CITE WITHOUT PERMISSION locate targets or control tacair strikes near the DMZ.77 Even the high-flying B-52s were restricted from operating north of Quang Tri City after one was struck by an SA-2 missile.78 Tacair continued to operate in Military Region I and Route Pack 1, but not without taking its own losses as seven jets were downed by NVA air defenses in April.79

Third, U.S. air power proved ineffective in the defense of Quang Tri as a result of the Vietnamization of the tactical air control system (TACS). Unlike weather or enemy air defenses, this factor was within U.S. control. The TACS was the organization responsible for integrating air power to support friendly ground forces. The TACS in

South Vietnam consisted of three levels. Overall responsibility for allocating air power in

South Vietnam fell to the Tactical Air Control Center (TACC) based near Saigon and manned by USAF and VNAF personnel. The TACC planned and coordinated air operations, and directed and, when necessary, diverted air assets to the four military regions. The second level of air control were the Direct Air Support Centers (DASCs) in each of the military regions. DASCs were tasked with distributing air assets to ground units based on air requests. For this role, they had direct radio contact with aircraft that checked in to verify missions or be diverted to higher priority/urgent requests. The third level of air control were the tactical air control parties (TACPs) assigned directly to

ARVN units. TACPs consisted of Air Liaison Officers (ALOs), responsible for coordinating and initiating air strike requests, along with ground and airborne Forward Air

77 Ibid., 24. 78 HQ PACAF Summary Air Operations Southeast Asia volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7. 79 Seven jets were downed by NVA air defenses in April. Ibid., 4-1.

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Controllers (FACs) who identified and marked targets and provided clearance for air strikes. 80

By the end of 1971, the VNAF had assumed responsibility for the DASC in MR I, responsible for supporting the ARVN 3rd Division. By contrast, the transition to VNAF control of the DASCs in MR II and III was not scheduled to take place until June 1972.81

From the outset, the Vietnamese DASC had the daunting task of handling the influx of hundreds of U.S., English-only speaking aviators crowding the skies and airwaves. The job proved impossible, however, because of the poor coordination between the VNAF Air

Liaison Officer (ALO) and the 3rd ID planning staff and the ineptness of VNAF forward air controllers (FACs). Inadequate equipment and training left the FACs unable to perform the critical task of visual reconnaissance (identifying targets and providing updated battlefield intelligence) and of air strike control (providing terminal strike control for CAS).82

Problems with both the ALO and FACs can be traced back to the rapid expansion of the VNAF as a result of Vietnamization. A shortage of qualified pilots left many ALO billets vacant or manned by junior ranking, inexperienced officers. Also, unlike the experienced American FACs, VNAF FACs were not pilots but observers who flew alongside inexperienced pilots assigned to fly O-1 observation aircraft. The breakdown of the TACS in MR I meant the VNAF could not effectively coordinate air strikes nor could the FACs effectively employ tacair even when the weather allowed.83 Not until June,

80 HQ PACAF CHECO Vietnamization of the Tactical Air Control System (23 September 1974), 2-9. 81 Ibid., 44-6. 82 Ibid., 75-77. 83 Ibid., 23-29.

26 DRAFT: DO NOT CITE WITHOUT PERMISSION following the fall of Quang Tri, was a U.S. TACS reintroduced to MR I, a move which proved critical to the retaking of Quang Tri.

The fall of Quang Tri is the story of the inability of the United States to use its firepower to compensate for the weakness of its ally. The defense at An Loc and Kontum considered next, however, demonstrate the decisive role U.S. air power played when not constrained by weather or air defenses and when operating with a functional tactical air control system.

The Battle in the South: MR III and the Siege of An Loc

The NVA attack in Military Region III was a direct thrust from the Cambodian sanctuaries down Route 13 towards Saigon. After a feint towards the more densely populated Tay Ninh Province, the NVA sought to destroy the northernmost ARVN stronghold at Loc Ninh and then isolate and destroy the ARVN position at An Loc.84 If the NVA could succeed in capturing An Loc, they would have 47 miles of open road to the capital of Saigon.85 The Communists committed 35,000 troops of three infantry divisions, one artillery division, and a tank regiment to this drive on the capital.86

The ARVN 5th Division and its supporting elements stood in the way of the NVA breakthrough. Two battalions of infantry and two batteries of artillery were located at Loc

Ninh; the remainder of the ARVN troops were located just south in An Loc or spread across a handful of fire support bases on the northern and western flanks of Binh Long province.87 As the attack unfolded, the Province Chief Tran Van Nhut, would commit an

84 Lam Quang Thi, Hell in An Loc (Denton: The University of North Texas Press, 2009), 41-42; ibid. Truong, 112. 85 Military Assistance Command Vietnam, Command History, March 1972- March 1973, Volume II, J-3. 86 James H. Willbanks, The Battle of An Loc (Bloomington: The Indiana University Press, 2005), 33. 87 Ibid., Willbanks, 30-31, 44.

27 DRAFT: DO NOT CITE WITHOUT PERMISSION additional 2,000 Regional Force and Popular Force units to the defense of An Loc, bringing the total force inside An Loc to 6,200 Vietnamese troops and 25 U.S. advisors.88

While the April 2 NVA feint at the ARVN firebases to the west in Tay Ninh province inflicted heavy losses on the ARVN defenders, intelligence soon indicated that the main thrust of the attack would come in Binh Long province along Route 13.89 On

April 5, the 5th VC division struck the Loc Ninh position with heavy artillery, tanks, and infantry. U.S. advisors brought continuous tacair, Cobra helicopter, and fixed-wing gunship attacks to break the first Communist assaults. While the ARVN resistance and aerial firepower held the Communists off for three days, these measures were ultimately insufficient to hold off the mass of the NVA attackers. As the U.S. advisors and U.S. forward air controllers (FACs) sought to apply the array of CAS fires, the complexity of orchestrating artillery, tacair, attack helicopters and fixed-wing gunships severely tested the ground and air controllers.90

The stubborn resistance at Loc Ninh had bought time for the defenders of An Loc to organize their defense. The Senior U.S. Adviser in MR III, General Hollingsworth, was confident that U.S. firepower could offset the massive numerical advantage of the attackers:

“Once the Communists decided to take An Loc, and I could get a handful of soldiers to hold and a lot of American advisors to keep them from running off, that’s all I needed. Hold them and I’ll kill them with air power; give me something to bomb and I’ll win.”91

88 General Tran Van Nhut, An Loc: The Unfinished War (Lubbock: The Texas Tech University Press, 2009), 110-111. 89Dale Andrade, America’s Last Vietnam Battle (Lawrence: The University of Kansas Press, 2001), 350. 90 Ibid., Willbanks, The Battle of An Loc, 50. 91 LTG Hollingsworth as quoted in Willbanks, The Battle of An Loc, 66.

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This then was the formula that would define U.S. efforts in all the defensive battles of the

Easter Offensive. ARVN troops willing to fight, supported by U.S. ground advisors,

FACs, and a TACS system, could use massive CAS and BAI to repel and eventually destroy the mechanized formations that outnumbered them by more than three to one.

The first ground assault on An Loc came on April 13. The ARVN defenders, by now cut off from Lai Khe to the south by the NVA 7th Division, were subjected to a 7,000- round, fifteen-hour artillery barrage; this was followed by an attack by two regiments of infantry and two dozen T-54 and PT-76 tanks.92 The ARVN defenders were dug in in the town center, a rectangular perimeter measuring 2km-by-1km; throughout the day, they repelled the attacking tanks and infantry with small arms and M-72 LAW anti-tank rockets.93 Once again, U.S. and Vietnamese air support was decisive in stopping the NVA advance. Having lost almost all of their artillery to NVA counter-battery fire, the defenders were entirely dependent on air power for their defense.

Building on the experience at Loc Ninh, U.S. advisors and FACs applied the range of air platforms in layers to defeat the NVA attack. B-52s were used against enemy staging and assembly areas while U.S. and VNAF tacair delivered air strikes closer to the perimeter. The closest fires were delivered by the rocket firing, AH-1 Cobra helicopter gunships augmented by the continuous presence of AC-119 and AC-130 gunships.94 U.S. advisors multiplied the number of sorties over An Loc by using a forward base at Bien

92 HQ PACAF Directorate, Tactical Evaluation Division CHECO Division, Battle for An Loc (5 April-26 June 1972), pp. 16; ibid., Willbanks, The Battle of An Loc, 72. 93 Ibid., Willbanks, The Battle of An Loc, 28. 94 Ibid., Willbanks, The Battle of An Loc, 77-78.

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Hoa for rearming and refueling tacair from carriers and airbases across Thailand and

South Vietnam.95

After two days of heavy attacks, the Communists had seized the northern half of

An Loc at a terrible cost. They had lost 23 tanks and countless infantry and these losses forced them to regroup.96 Brigadier General Giffert, the number two U.S. advisor in MR

III, was blunt in his assessment of this first wave: “I really believe that without these [B-

52 Arc Light strikes and pre-planned tacair] the city would have fallen, because I think the infantry would have gotten in with the tanks.”97 As they weathered the first Communist assaults, the ARVN received critical reinforcements on April 14 as the ARVN 1st

Airborne Brigade was successfully inserted by helicopter onto the high ground south of the town.98

The NVA renewed their assault on April 19 with simultaneous thrusts at the

Airborne units in the south and the 5th Division positions inside the town. After fierce resistance, the Airborne troops were driven off the southern high ground and lost their artillery in the process, once again leaving the defenders with no artillery inside the perimeter. This second battle raged from 19 to 22 April in much the same form. The

NVA battered the town with artillery, tanks, and infantry assaults while the ARVN used their light weapons and heavy CAS to repel the attackers.

After another weeklong pause, the Communists made their final attempt to destroy the garrison of An Loc on May 11. The 5th and 7th NVA divisions threw seven regiments of infantry against the northeastern and western flanks of an ARVN perimeter that had

95 Ibid., Willbanks, 88. 96 Ibid., Truong, 123; ibid., Nhut, 123. 97 Ibid., MACV, Command History, Vol. II., J-13. 98 Ibid., Nhut, 126.

30 DRAFT: DO NOT CITE WITHOUT PERMISSION shrunk to 1 km by 1.5 km. Once again they relied on artillery to break ARVN resistance; in the first four hours they fired 7,500 rounds into the ARVN positions and another 10,000 rounds in the twelve hours after sunrise.99 The NVA sought to diminish the effects of U.S. air power by deploying SA-7 infrared-guided, manportable missiles in large numbers.

These systems were effective against slow, prop-driven FACs, helicopters, and fixed-wing gunships and their introduction forced the U.S. to withdraw many of these aircraft from the immediate battle area.100

The last NVA assault collided with the heaviest and best orchestrated aerial fires of the campaign. Acting on indicators of an impending attack, Hollingsworth had interceded with Abrams to secure the maximum available air support on May 11. With Abrams’ consent, Hollingsworth was able to vector 300 tacair sorties and 30 B-52 Arc Light missions into An Loc on May 11th alone; over the next four days, he pushed an average of

260 tacair sorties into An Loc to hammer NVA units and assembly areas. Desperate to maximize the effects of these sorties, U.S. advisors cleared the use of B-52 Arc Light strikes within 600 meters of the perimeter.101 Confronted with these withering fires, and bedeviled by problems with tank/infantry coordination, the last big NVA push ground to a halt.

While the NVA continued to shell the town with 2,500 rounds per day from May

13-16, the greatest danger had passed. Communist losses and overwhelming aerial firepower enabled the ARVN to hold An Loc. By 15 June, the Airborne were strong enough to push back onto the high ground to the south of the town and lift the siege.102

99 Ibid., Willbanks, The Battle of An Loc,117. 100 Ibid., HQ PACAF, Battle for An Loc, 57-59; ibid., Truong, 129. 101 Ibid., MACV, Command History, Vol. II., J-23-25. 102Ibid., MACV, Command History, Vol II., J-29.

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By this time, An Loc had been reduced to a charnel house. The NVA lost three divisions with their estimated losses coming to 10,000 killed and 15,000 wounded. The

ARVN defenders had suffered 2,300 dead and 3,100 wounded. The town had been almost entirely destroyed by 78,000 rounds of Communist artillery, more than 700 B-52 Arc

Light strikes, and countless tacair attacks. 103

Even more than in MR I and MR II, the role of air power in defeating the

Communist offensive appears to have been the decisive element. The circumstances of the siege made An Loc a natural experiment in the influence of air power in support of ground troops. In contrast to the battles of Kontum and Quang Tri, the defenders of An

Loc never enjoyed the support of ARVN artillery, naval gunfire, or tank support. Instead, they were entirely reliant on small arms, M-72 LAWs, and U.S. and Vietnamese air power.104 For the duration of the siege, they also depended almost entirely on aerial resupply by parachute delivery.105

ARVN commanders were unequivocal in their statements about the importance of

CAS and BAI in the outcome at An Loc. In his postwar study of the battle, LTG Truong explained the outcome in these terms:

“An Loc had held against overwhelming odds. To a certain extent this feat could be attributed to the sheer physical endurance of ARVN defenders…. But the enemy’s back had been broken and An Loc saved only because of timely B-52 strikes.”106

103 Ibid., Willbanks, The Battle of An Loc, 146-147; ibid., HQPACF, CHECO Division, Battle for An Loc, 63-65. 104 Ibid., HQPACF, CHECO Division, Battle for An Loc, 55. 105 ibid., HQPACF, CHECO Division, Battle for An Loc, 26-36. 106 Ibid., Truong, 131. Lam Quang Thi, Truong’s wartime deputy, came to similar conclusions in his history of the battle of An Loc: “What then were the causes of success of the defense of An Loc? First, it was the air support available that made the biggest difference between An Loc and Dien Bien Phu. Day after day, B- 52 sorties hit NVA assembly areas, logistical installations, even the first echelon assault units.” (Lam Quang Thi, Hell in An Loc, 209).

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Captured enemy documents revealed similar opinions on the Communist side. A handwritten letter seized on April 18 from a political commissar of the 9th VC Division to

COSVN Headquarters explained the Communist failure in terms of the their inability to coordinate tanks and infantry and “the effects of tactical air and B-52 strikes [that] were unbelievably devastating.”107

Still, the tactical application of such volumes of air power would not have been possible without effective coordination mechanisms. U.S. ground advisors, working with

U.S. and Vietnamese FACs, were able to focus these fires onto the enemy while minimizing the collateral damage to ground forces. During the course of the battle, U.S.

FACs developed increasingly effective procedures for controlling the mass and variety of platforms in the battle area.108 While less visible than the hardware or munitions employed, the organizational and procedural software of this system helps explain the success of air power at An Loc and the failure of CAS/BAI missions in the opening phases of the defense of Quang Tri.

U.S. air power could not have been effective without the resistance of ARVN forces and U.S. advisors. On the third day at Loc Ninh, the collapse of ARVN resistance had vitiated the U.S. advisors’ plans to hold the position with CAS and BAI. At An Loc, by contrast, the encircled ARVN forces fought tenaciously. As General Abrams aptly summarized:

“I doubt the fabric of this thing could have been held together without U.S. air. But the thing that had to happen before that is the Vietnamese, some numbers of them, had to stand and fight. If they didn't do that, ten times the air wouldn’t have stopped them”109

107 Ibid, MACV, Command History, Vol. II., J-15. 108 For a detailed discussion of the FAC system at An Loc, see HQPACF, CHECO Division, Battle for An Loc,19. 109 Ibid., Sorley (ed.), Vietnam Chronicles, 826.

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The Battle in the Central Highlands: MR II and the Siege of Kontum

With the battles in MR I and MR III underway, the NVA prepared to launch its third major attack, this time from Cambodia into the thinly populated Central Highlands.

If the NVA could destabilize the coastal areas of MR II and seize Kontum and Pleiku in the highlands, they would be able to split the Republic of Vietnam in two. The

Communists invested 20,000 troops of three NVA divisions and separate regiments as well as heavy artillery and an estimated 400 tanks in this third campaign.110

The NVA’s plan was to proceed in three steps. First, they would cut the flow of supplies from the coast to the ARVN forward positions in the highlands at Tac Canh,

Kontum, and Pleiku. Second, they would seize Rocket Ridge, the strip of high ground that dominated the routes leading both to Tac Canh and Kontum. With the high ground in their possession, the NVA would isolate and destroy the major ARVN garrisons in series, opening the gate to a triumphant march to the sea.

The ARVN II Corps that stood in their way was considered the weakest of the four corps in the South Vietnamese army. The commanders, from the Corps Commander

General Dzu down to the regimental commanders, were regarded as ineffectual and U.S. advisors were pessimistic about their ability to withstand a major attack.111 On 28

December 1971, Brigadier General George Wear, the senior military advisor in II Corps, described the ARVN situation to General Abrams in these terms:

I wish I could be a lot more optimistic than I really am about the ARVN in II Corps. And I think this time last year I was. They can just about handle the local forces within the boundary. Our experience has been…that when the NVA well-trained

110 Capt. Peter Liebchen, Kontum: Battle for the Central Highlands (30 March- 10 June 1972)(HQ PACAF, Directorate of Operations Analysis CHECO/CORONA Harvest Division, 27 October 1972), 3; ibid., Willbanks, Abandoning Vietnam, 139. 111 Ibid., Andrade, 207-208.

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units come across the border, the ARVN just hasn’t stood up against them…. The two divisions [22nd and 23rd ARVN] I don’t think they’ve really improved in the 17 months I’ve watched them. Their strength runs about the same, 71 to 76 percent…. The leadership problem you know…. I have noticed that when a unit really got into it, and didn’t have a choice, they fought pretty well.”112

Still, Wear’s superior, John Paul Vann, hoped that even moderate ARVN resistance would allow him to focus B-52 strikes on the attacking formations and break the NVA bid to seize the highlands.113

Vann was able to impose his thinking on the malleable ARVN II Corps

Commander General Dzu. Over the objections of his own military advisor, BG Wear,

Vann pushed the 22nd ARVN Division forward to meet the anticipated NVA thrust near

Tac Canh.114 The 23rd Division would be spread across the coastal strongholds of MR II.

Vann’s intent was to meet the NVA invasion forward of Kontum and defeat it there with

U.S. air power.115

Vann sought to disrupt the NVA buildup in the highlands using B-52 Arc Light strikes. The limiting factor in these spoiling attacks was direct observation. Many ARVN commanders were reluctant to patrol aggressively and pin down the locations of the major enemy formations.116 Still, in the first three months of the year, Vann employed the B-52s in a wide-ranging, BAI campaign against the NVA in the western sanctuaries of MR II.

The volume of air power was remarkable. In January and February the bombs of more than 100 B-52 bombers fell on the Central Highlands with more than eighty of those coming in February alone.117 As prisoner and defector reports would later reveal, these

112 BG George Wear as quoted in ibid., Sorley (ed.), Vietnam Chronicles, 730-731. 113 Ibid., McKenna, Kontum: The Battle to Save South Vietnam, 47; ibid., Andrade, 214-215, 217. 114 Ibid., McKenna, 30. 115 Ibid., McKenna, 52, 82-84. 116 Ibid., MACV Command History January 1972-March 1973, Vol. I, K-1; ibid., Andrade, 213; ibid., McKenna, 29, 87. 117 Ibid., McKenna, 53, 98.

35 DRAFT: DO NOT CITE WITHOUT PERMISSION thinly observed strikes had a devastating impact on the NVA units. One POW from the

320th NVA Division captured in mid-May testified that his regiment of 2,500 men had suffered 1,200 casualties before it launched its first attack on Kontum. Equally important, these attacks appear to have delayed the start of the NVA campaign in the Central

Highlands. This delay meant that the third NVA campaign would unroll after the campaigns in the north and south had largely culminated.118 This would enable the U.S. military to focus the full weight of its air power on Kontum when the test came.

Despite Vann’s best efforts, the preparatory phases of the NVA offensive were broadly successful. The NVA seized An Khe pass in early April and cut the major line of supply from the coast to the highlands; it would take ARVN and South Korean forces a full month to clear this roadblock and restore steady supplies. At the same time, the NVA diversionary attacks in coastal Binh Dinh province allowed VC cadre to seize control in a number of villages and towns.119 Most important, in early April the NVA began to isolate and attack the series of ARVN firebases strung out from north to south along Rocket

Ridge. While those firebases held out for a time, by the last week of April these posts began to fall or withdraw under heavy NVA pressure.120 Once ensconced on those dominating heights, the NVA began to assemble the troops and artillery necessary to launch its deliberate attacks on Tan Canh and Kontum.121

On 23 April, the first major blow fell on two regiments of the 22nd ARVN Division at Tac Canh and Dak To. Neither regiment was prepared for the scale and ferocity of the assaults; two NVA Divisions and four separate regiments attacked the two ARVN

118 Ibid., McKenna, 53, 193-194. 119 Ibid., McKenna, 74, 132; Andrade, 220-227. 120 Ibid., MACV Command History, Vol I., K-5. 121 Ibid., Truong, 85; ibid., Andrade, 232.

36 DRAFT: DO NOT CITE WITHOUT PERMISSION regiments in their positions. In addition to their use of heavy artillery and tanks, the NVA employed AT-3 Sagger antitank missiles for the first time. These missiles quickly knocked out the ARVN tanks and command posts and contributed to the complete disintegration of the 42nd and 47th Regiments.122 By 24 April, both positions had fallen to the NVA, the 22nd ARVN Division had been shattered, and Vann’s plan of forward defense lay in tatters. In the rapid collapse, the ARVN lost twenty-three 105mm howitzers, seven 155mm howitzers, ten M-41 tanks, and 14,000 rounds of artillery ammunition. Much of this materiel fell into NVA hands intact; many of these weapons would soon be turned on the defenders of Kontum.123

Vann immediately set to work on a new line of defense. Colonel Ba, the commander at Kontum, convinced Vann to bring the three regiments of the 23rd Division to defend the city, bringing the total garrison to around 5,000 troops. Vann also set his new deputy, Brigadier General Hill, to work on the problem of controlling artillery fires and air support. Anticipating the high volume of U.S. and VNAF air strikes in the coming battle, he announced that there would be a single air boss in an OH-58 helicopter acting as a “traffic cop” in the skies over Kontum.124 More important, Hill brought in a new Air

Liaison Officer, USAF Colonel Swenholt, to reorganize the air effort at II Corps HQ in

Pleiku. In contrast to the situation in MR I, the II Corps Direct Air Support Center

(DASC) had not completed its transition to South Vietnamese control by the time of the offensive and this made a restoration of U.S. control over air operations far simpler.125 As

122 Ibid., McKenna, 100-103, 107. 123 Ibid., Andrade, 250; ibid., McKenna, 120. 124 Ibid., McKenna, 126-127. 125 Ibid., Liebchen, 33.

37 DRAFT: DO NOT CITE WITHOUT PERMISSION the Senior Fighter Duty Officer at II DASC later explained, the procedures used to control tacair and B-52s varied considerably:

TACAIR is used with FACs. FACs go out and look for targets, or the ground commander will direct them to a target or give them an area to check out. He calls back here with the coordinates to be cleared, and also requests air at the same time. We clear the target here by going through ARVN channels. After that’s done, we have our incoming air that’s been fragged to us; we parcel it out to the FAC depending on what priority target he’s got…. [As for the B-52s] Frankly, that’s no longer an Air Force weapon. We fly the airplanes, but the (U.S.) Army puts in the target request; they handle the clearing, etc.126

As the volumes of air support increased and the battle for Kontum began in earnest, this procedural backbone for cooperation between USAF controllers and U.S. ground advisors proved the key to the successful application of CAS and BAI.

The NVA paused for three weeks to prepare for its attack on Kontum. In the intervening period, Colonel Ba and Vann directed the three regiments of the 23rd ARVN

Division to dig in north of the city to block the anticipated southward thrust. Unlike at An

Loc, the defenders would enjoy the support of a full complement of artillery: forty-four

105mm and four 155mm howitzers.127 Farther north and west, ARVN Ranger units clung to two positions in the hopes of slowing the NVA advance.128

The battle at the gates of Kontum would not open until May 14. In the preceding week, the stand by Rangers at Polei Kleng had bought additional time and enabled Vann and Ba to bring a crescendo of air strikes onto the NVA forces. On May 12 alone, 78 tacair and 25 B-52 Arc Light attacks rained down on the attackers as they approached the city from the north. Whether out of bluster or necessity, the NVA dispensed with their

126 Ibid., Liebchen, 33-34. 127 Ibid., McKenna, 135. 128 Ibid., MACV Command History, Vol. I, pp. K-14; ibid., Andrade, 257.

38 DRAFT: DO NOT CITE WITHOUT PERMISSION traditional, multiday artillery barrage and instead launched 3,000 troops supported by tanks in a bid to repeat their easy victories at Tac Canh and Dak To.129

A combination of stiff ARVN resistance and massive air support held the attackers at bay from 14 to 16 May. The regiments of the 23rd Division poured small arms fire and artillery onto the attacking columns; hunter-killer teams armed with M-72 LAWs wiped out the tanks that managed to breach the frontlines. The United States brought in its newest tank killer in the form of the XM-26 “Hawk’s Claw”: a UH-1B Huey helicopter armed with BGM-71 TOW anti-tank missiles. Firing from medium altitude, the two experimental aircraft knocked out seven of the ten attacking tanks on the first day.130 At the same time, the hourly B-52 Arc Light strikes hammered the attacking formations and wreaked havoc on NVA artillery and supply.131

While the NVA attacked from 14 to 16 May and again on 19 May, the cumulative damage to their forces was immense. As one POW taken on 23 May from the 48th NVA

Regiment recounted, the company strength in his regiment had fallen to ten men and the units were critically short on food and ammunition. By Vann’s own estimate, the enemy had no more than 15 to 25 functioning tanks by 24 May.132

A week later, the NVA launched its second wave of attacks on Kontum. This time they managed to suppress the ARVN artillery while five regiments of infantry, an understrength battalion of tanks, and three Sapper battalions simultaneously hit the northern and southeastern sides of the ARVN perimeter.133 Exploiting seams in the

ARVN defense, the NVA attackers drove deep salients into Kontum. By the night of 27

129 Ibid., Andrade, 287. 130 Burns 75-77. 131 Ibid., McKenna, 173, 197. 132 Ibid., McKenna, 207, 209. 133 Ibid., Truong, 102; ibid., Andrade, 301.

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May, the NVA held half the city and the ARVN were forced to draw into a tighter perimeter. With bad weather grounding much of the tacair, it fell to the B-52s and TOW firing helicopters to stop the NVA advance. Vann and his senior advisor on the ground,

Colonel Rhotenberry, brought fifty B-52 Arc Light sorties to bear on Kontum on 28 May alone; with some trepidation, the U.S. advisors brought the B-52 strikes to within 700 meters of the friendly lines.134 The UH-1B/TOW aircraft, for their part, played a critical role in blunting the tank assaults. The UH1-B/TOWs knocked out ten tanks on the first day and two on the second; their precision fires also destroyed a number of point targets inside the city while minimizing the risk to ARVN forces.135

The NVA attacks culminated on 29 May. While the Communists had managed to break into ARVN lines, the cumulative effects of CAS, BAI, and ARVN resistance had stopped their momentum. Unable to dislodge the NVA with air strikes alone, the ARVN launched a week of ground assaults to clear the city:

“Fierce fighting, much of it was brutal, hand-to-hand combat, raged between the [ARVN and NVA] bunkers. Hand grenades flew and rifles fired point blank. It was the only way for the South Vietnamese to win the battle…. It was ironic that in the final hours of the battle for Kontum air power was unable to defeat the North Vietnamese, although it had done much to blunt their offensive. No one would deny that air power had saved the Central Highlands, but it took infantry to punctuate the victory.”136

By 5 June, the city was fully in ARVN hands and the siege of Kontum was over.

As at An Loc, the costs of a successful defense were enormous. Estimates of NVA casualties at Kontum ranged as high as 16,000 with a minimum of 5,700 dead. According to prisoners and defectors, many NVA regiments had fought until only 400 of 2,500 men

134 Ibid., McKenna, 232, 240. 135 Burns, 74. 136 Ibid., Andrade, 317.

40 DRAFT: DO NOT CITE WITHOUT PERMISSION remained. The official ARVN losses were more modest but likely understated at 400 confirmed dead and over 1,600 wounded.137

The role of air power in defeating the Communist attack on Kontum was indisputable. Tacair and particularly B-52 Arc Light strikes shredded the NVA units and destroyed many of their supplies and most of their artillery. Between 14 May and 8 June,

300 B-52 Arc Light missions alone dropped millions of pounds in explosives in 25 days in the vicinity of Kontum.138 Vann’s private assessment to Abrams on 29 May was as follows:

“The consensus is that Arc Light results greatly exceed kills by all other means. My personal synthesis of all available information indicates that most enemy units are at 50% or less of their entry strength in early 1972. Nearly all PW and Hoi Chanh [defectors] reports indicate average company strength around 20-25 [%].”139

Postwar, North Vietnamese internal histories pointed to U.S. air power and aerial resupply as nearly insurmountable obstacles in the An Loc campaign:

“even though we had concentrated the maximum possible amount of our air defense forces for the key, decisive battle in Binh Long [An Loc], we were unable to prevent the enemy from being able to constantly resupply his forces and to replace and replenish his personnel. Although Binh Long was surrounded and we had blocked the road from Chon Thanh up to Binh Long, the enemy continued to be able to bring in reinforcements so his strength constantly increased. Fire support provided by tactical aircraft and B-52s played the decisive role in repelling our assaults and enabling the enemy to defend Binh Long. The reality of the situation clearly demonstrated one thing: since we did not have sufficient strength to disrupt the enemy’s air superiority, even if we had all of the enemy’s ground access routes sealed off tightly, it would still be difficult for us to prevent the enemy from bringing in additional forces and adding additional firepower to rescue the enemy’s surrounded and threatened position. Under those conditions, the decision to try a second time to assault and overrun the Binh Long province capital was not a good decision for us to have made.…140

137 Ibid., McKenna, 263. 138 Ibid., McKenna, 257. 139 Ibid., McKenna, 239. For similar opinions by other US sources, see HQ MAC-V The Nguyen Hue Offensive MACDI Study 73-01 12 January 1973, 7 and HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, VII-2. 140 “The Nguyen Hue Offensive Campaign in Eastern Cochin China, 1972 – For Internal Distribution Only” [Chien Dich Tien Cong Nguyen Hue Mien Dong Nam Bo Nam 1972 – Luu Hanh Noi Bo], Editorial

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As at An Loc, and in sharp contrast with Tac Canh, the defenders at Kontum had held their ground in the face of superior numbers, numerous tanks, and withering artillery fires.

Without such resistance, and without the support of U.S. ground advisors, FACs, and the

II Corps DASC, the NVA would have been able to roll through Kontum and drive to the coast.

Summary of Air power in the MR I, II, and III

In sum, the results of air power in the direct attack of fielded forces in the three initial battles of the Easter Offensive were mixed. Constrained by weather, enemy air defenses, and an inadequate TACS in Military Region I, air power failed to stop the fall of

Quang Tri. At Kontum and An Loc in MR II and III, however, air power proved decisive.

With better flying weather, a more moderate threat environment, and an operative TACS, air power integrated into the ARVN’s scheme of maneuver halted the North’s assault.

The next section evaluates an alternative explanation for the defeat of the NVA: the

Linebacker I air interdiction campaign.

Linebacker I: 10 May – 23 October 1972

The mixed results from the early battles of the Easter offensive demonstrate both the capability and the constraints of air power in the direct attack of enemy fielded forces.

This section continues to evaluate U.S. air power, this time in the indirect attack of the

Direction: Colonel General Hoang Minh Thao, Major General Cao Pha, Senior Colonel Vo Cong Luan. Author: Senior Colonel Le Buoi. Editor: Senior Colonel Ho Ban, Military History Institute of the Ministry of Defense, Hanoi, 1988 (Translation by Merle Pribbenow), 87.

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NVA with an air interdiction campaign. As in the latter stages of Rolling Thunder, the

United States turned to a denial strategy in an effort to erode Hanoi’s hopes of winning the war by disrupting its transportation networks.

In reaction to the fall of Quang Tri in early May and ongoing battles at An Loc and

Kontum, President Nixon ordered the mining of Haiphong Harbor and attacks against

North Vietnam’s railways and distribution system.141 Codenamed Linebacker I, the air campaign was meant to stall the NVA’s offensive by denying it the ability to resupply its forces.142 This section examines Linebacker I by describing the North Vietnamese transportation network, examining U.S. air operations aimed at the deep interdiction of

Hanoi’s supply lines, and evaluating the impact these air strikes had on NVA operations in

South Vietnam.

North Vietnam’s Transportation System

The North Vietnamese relied upon two major supply routes for its imports. Soviet ships offloaded at Haiphong Harbor, where goods were transported via rail to storage facilities near Hanoi and Haiphong. Chinese supplies arrived via a 50-mile rail line connecting southeastern China and Hanoi. A northwest railway provided a tertiary route through southwest China.143

The Haiphong, northeast, and northwest railways converged north of Hanoi, where a single rail line crossed the Red River over the Paul Doumer Bridge. This massive structure spanned over a mile and handled both rail and road traffic. As a critical choke

141 CINCPAC, Command History 1972, Volume II, Air Force Historic Research Agency, K712.01 1972 v.2, 538-39. 142 HQ Seventh Air Force, History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, AFHRA K740.04-24 72/05/10-72/10/23, preface. 143 HQ Seventh Air Force, Commanders’ Conference 18-19 July 1972 AFHRA K168.06-228 72/07/18- 72/07/19, 3.

43 DRAFT: DO NOT CITE WITHOUT PERMISSION point, it had been repeatedly attacked during the Rolling Thunder air campaign.

Following the 1968 bombing pause, the North Vietnamese repaired and fortified the bridge against future air strikes.

Once passing Hanoi, trains traveled south through the city of Thanh Hoa where another large bridge provided a second major choke point. From Thanh Hoa, trains headed south down the North Vietnamese panhandle to the city of Vinh (see Map II).

From here, supplies were moved via truck or boat, or packed on foot across the DMZ or westward into Laos along the Ho Chi Minh Trail.

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Map II: North Vietnam Transportation and Route Package144

In addition to the rail network, the North Vietnamese road system roughly paralleled the railways and, at key choke points, utilized the same bridges, such as the

Paul Doumer and Thanh Hoa. In addition, the North Vietnamese constructed a series of small pipelines to transport fuel from China to North Vietnam and further south to the

144 http://www.kalimera.org/nf104/ab/ch_5/iv.html accessed 30 Apr 2015

45 DRAFT: DO NOT CITE WITHOUT PERMISSION base areas of Laos, Cambodia, and South Vietnam. These pipelines made the fuel supply network more resilient in the face of U.S. air attacks.145

In response to the 31 March invasion, the United States conducted a series of small air strikes, codenamed Freedom Train, against North Vietnamese transportation, storage, and military facilities south of the 18th parallel.146 Air strikes north of Route Pack 1 escalated significantly, however, with the commencement of Linebacker I on 10 May.

The systematic air campaign was designed to dismantle the North Vietnamese transportation system.147

A significant operational innovation of Linebacker I was the USAF’s employment of laser-guided bombs against transportation, power generation, and industrial targets.148

The U.S. Air Force and Navy’s development of precision-guided munitions dates back to

World War II.149 In 1968, laser-guided bombs were introduced into Southeast Asia and by

1972, tens of thousands of the smart bombs had been employed against trucks, bridges and targets of opportunity along the Ho Chi Minh Trail and against NVA troops in South

Vietnam.150

145 HQ PACAF, CORONA HARVEST: USAF Air Operations in Southeast Asia 1 Jul 1972 – 15 August 1973 vII. AFHRA K717.0423-23 1 Jul 72 – 15 Aug 73, v2, IV-84-85. John Prados, The Blood Road: The Ho Chi Minh Trail and the Vietnam War (New York: Wiley & Sons, 1999), pp. 339. 146 CINCPAC Command History 1972, volume I, AFHRA K712.01 1972 v1, 151-4; HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, 7; History of the 8th TAC Fighter Wing, v1 “Narrative,” AFHRA K-WG-8-H1 Apr-Jun 1972, v.1, 36. 147 HQ CINCPAC, Command History 1972 v. II K712.01 1972, 538. Airstrikes in North Vietnam rose from 1,644 in April to 5,438 in May, Randolph, Powerful and Brutal Weapons, 282. 148 Due to restrictions for carrier operations the U.S. Navy did not employ a large number of laser-guided bombs. They employed electro-optic guided weapons, as did the Air Force, but these missiles did not prove to be as effective as laser-guided bombs. As a result most Navy strikes utilized free fall bombs. For area targets, such as rail yards, the Air Force also employed unguided bombs. 149 For a history of the development of precision guided munitions see, Paul Gillespie, Weapons of Choice (Tuscaloosa, Al: University of Alabama Press, 2006). 150 HQ Seventh Air Force An Analysis of Laser Guided Bombs in SEA, AFHRA K741-4 28 Jun 1973, 2.

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On 10 May, a dozen USAF F-4s dropped twenty-two 2,000-pound, laser-guided bombs disabling the Paul Doumer bridge.151 Precision munitions had the added benefit of minimizing collateral damage, which, in turn, allowed air strikes to be conducted against targets located near civilian populations.152 Increased accuracy, coupled with larger warheads of 2,000 to 3,000 pounds, inverted the calculus of war planners from that of determining the number of air strikes required to destroy a given target to calculating the number of targets that could be destroyed on a single mission. Laser-guided bombs dropped from medium altitude further reduced the risk to aircrew now kept above the reach of AAA and SA-7s.153

For all these advantages, laser-guided bombs also had drawbacks, the biggest of which was the requirement for visual flight conditions.154 Lasers do not penetrate clouds and, given the weather patterns in Southeast Asia, this restricted when laser-guided bombing could be conducted. Soon the weather forecast became a primary consideration for which targets could be struck. Weather conditions remained relatively good May through July allowing 60% of the scheduled precision-guided strike packages to be flown.155 In August, however, the arrival of the monsoon season restricted air strikes, forcing the Air Force and Navy to rely instead on inaccurate, long-range radio navigation

(LORAN) and air-to-ground radar bombing against area targets.156

151 HQ Seventh Air Force, History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, 10. In addition seven, 2000 pound television guided bombs were employed. Due to signal interference and lower altitude releases only two of the alternative electro-optical guided strikes were employed by the USAF during Linebacker I. The U.S. Navy also conducted a limited number of precision strikes with these weapons. 152 History of the 8th TAC Fighter Wing, v2 “Supporting Documents,” AFHRA K-WG-8-H1 Apr-Jun 1972, v.2, 7. HQ Seventh Air Force, History of Seventh Air Force 1 July 1971 – 30 June 1972, 301. 153 History of the 8th TAC Fighter Wing, v1 “Narrative,” 39. 154 HQ Seventh Air Force An Analysis of Laser Guided Bombs in SEA, 6. 155 The USAF conducted 19 Linebacker missions in May, 18 in June, 14 in July. HQ Seventh Air Force History of Linebacker Operation 10 May 1972 – 23 Oct 1972, 73. 156 HQ Seventh Air Force History of Linebacker Operation 10 May 1972 – 23 Oct 1972, 25.

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A second drawback of laser-guided bombing in high threat areas was its restriction to day strikes because of the daylight requirements for the Pave Knife electro-optic sensor.157 An earlier generation of laser designators had been employed over a relatively benign South Vietnam and Ho Chi Minh Trail, but these hand-held devices relied on a stable and predictable flight path.158 Such tactics were untenable over the highly defended

Hanoi, however, and in response, the USAF developed the Pave Knife system which could be operated from the backseat of an F-4 while the pilot maneuvered the aircraft against threats. 159

In addition to the restriction of laser-guided bombing in high threat environments to day use only, the USAF had only six of the Pave Knife pods in Southeast Asia. By

July, two aircraft losses had reduced the number of pods to four, forcing strike packages to be designed around protecting the aircraft carrying these precious devices.160 Close air patrol (CAP) and escort fighters shielded the strikers against MiGs, while other F-4s dispensed a chaff corridor over the target area to disrupt enemy search radars and F-105s on suppression of enemy air defense (SEAD) missions launched preemptive anti-radiation missiles to deter SA-2 operators from turning on their radars. Strike missions had as many as one hundred aircraft, which included tankers, electronic jammers, and search and rescue assets all tasked to protect a handful of strikers.161

157 HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, V-5. 158 The older devices were the Pave Nail (OV-10), Pave Turkey (AC-130), and ZOT systems. History of the 8th TAC Fighter Wing, v1 “Narrative,” 38. 159 HQ Seventh Air Force History of Linebacker Operation 10 May 1972 – 23 Oct 1972, 53; History of the 8th TAC Fighter Wing, v1 “Narrative,” 38; HQ PACAF CORONA HARVEST: USAF Air Operations in Southeast Asia 1 Jul 1972 – 15 August 1973 vII. AFHRA K717.0423-23 1 Jul 72 – 15 Aug 73, v2, IV-61. 160 HQ Seventh Air Force History of Linebacker Operation 10 May 1972 – 23 Oct 1972, 54. 161 HQ Seventh Air Force History of Linebacker Operation 10 May 1972 – 23 Oct 1972, 13.

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Despite the complexity of the packages, the initial laser-guided air strikes were operationally remarkably successful, disabling the Paul Doumer Bridge on 10 May and the

Thanh Hoa Bridge on 13 May. This effectively cut the North Vietnamese rail system into thirds, forcing the shuttling of goods from the Chinese border to Hanoi, Hanoi to Thanh

Hoa, and Thanh Hoa to Vinh.162 The USAF conducted primarily laser-guided attacks in

Route Pack 5 and 6 near Hanoi from May through July (see Table 1 below). In addition to these precision air strikes, over one thousand air strikes were conducted north of Route

Pack 1 by Air Force and Navy jets employing free fall munitions aimed at rail yards, rolling stock, bridges, and storage facilities. This combination of precision and conventional bombing effectively disabled the North Vietnamese rail system.163

With the arrival of the monsoon season in August came a scarcity of days available for laser-guided bombing.164 The NVA was showing no sign of calling off the offensive, prompting the White House to pressure the Air Force and Navy to increase the bombing near Hanoi, Haiphong, and the Chinese border.165 The number of air strikes in Route Pack

6 went up but, with overcast skies, most of the bombs were dropped unguided through the clouds with far less accurate bombing techniques.166 Table 1 below denotes the USAF shift from precision to free fall bombing due to the combination of poor weather and political pressure from Nixon to continue air strikes.

162 Vogt, John “Speech Delivered by General John W. Vogt, CINCPACAF, To Air Force Association,” Honolulu, HI, 15 Nov 1973, AFHRA K168.06-234 73/11/15-73/12/04, 10; HQ Seventh Air Force History of Seventh Air Force 1 July 1971 – 30 June 1972, AFHRA K740.01-25 197110701-19720630 v1, 302. 163 Randolph, 287. A.J.C. Lavalle, ed., The Tale of Two Bridges and The Battle for the Skies Over North Vietnam (Washington: Office of Air Force History, 1985), 84. 164 HQ PACAF, Summary Air Operations Southeast Asia volume XCVII August 1972, AFHRA K717.3063 Aug 1972, 4-1. 165 HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, 25; “Message from the Chairman of the Joint Chiefs of Staff (Moorer) to the Commander in Chief, Pacific (McCain),” FRUS, 1969-1976 Volume VIII, Vietnam, January-October 1972, Document 230. 166 HQ PACAF Summary Air Operations Southeast Asia volume XCVII August 1972, 4-2.

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Month Laser-Guided Missions Free Fall Missions May (21 days) 40 5 June 46 5 July 42 15 August 21 22 September 25 120 October (23 days) 7 97 Total (447) 183 264 Table 1: USAF Major Strike Activity in Linebacker I167

Evaluating Linebacker I

The precision air strikes of Linebacker I had an immediate impact on North

Vietnamese rail traffic, creating a backlog of trains at the Chinese border.168 Hanoi diverted labor, equipment, and supplies in an effort to repair the damaged rail, roadways, bridges, and vehicles.169 Further attacks on POL (petroleum, oil and lubricants) forced the dispersal of stockpiles, increasing the difficulty of storing and moving fuel south.170 The impact of the interdiction campaign was a significant rise in the time and cost required for the North Vietnamese to resupply their forces in the South.171

An assessment of Linebacker I conducted by Pacific Air Force Headquarters

(PACAF) at the beginning of June was optimistic, estimating that the limited supplies

167 Data on fixed target attacks was taken from April – October HQ PACAF monthly Summary of Air Operations South East Asia. Not included are two electro-optic guided bombing missions which took place in May and July. 168 HQ Seventh Air Force, Commanders’ Conference 18-19 July 1972, 1. 169 “The 1972 Quang Tri Offensive Campaign, (Secret)” Military Art Faculty of the Military Science Institute, Hanoi 1976, 76 (from Lessons learned Section). 170 HQ PACAF CORONA HARVEST: USAF Air Operations in Southeast Asia 1 Jul 1972 – 15 August 1973 vII. AFHRA K717.0423-23 1 Jul 72 – 15 Aug 73, v2, IV-9. 171 HQ PACAF CORONA HARVEST: USAF Air Operations in Southeast Asia 1 Jul 1972 – 15 August 1973 vII. AFHRA K717.0423-23 1 Jul 72 – 15 Aug 73, v2, IV-59.

50 DRAFT: DO NOT CITE WITHOUT PERMISSION flowing south would not support sustained NVA operations.172 In early August, a mixed assessment by the Joint Chiefs of Staff (JCS) concurred that Linebacker I had substantially disrupted the enemy’s transportation and distribution system. They also concluded that

Hanoi had persisted in pursuing its goals in the South, prompting the JCS to call for an escalation in air strikes in the North.173 By October, a new PACAF report was more pessimistic, estimating that the North Vietnamese had now generated the capacity to import by truck 10,000 tons of cargo daily from China, twice the volume they had been able to muster by ship and rail prior to Linebacker I.174 A recently declassified (2013) internal Air Force evaluation of the Easter offensive conducted in the fall of 1972 concluded that:

“[i]n spite of the substantial U.S. air effort devoted to the Linebacker operation, we were unsuccessful in our objective of isolating NVA from its outside sources of supply. We should have recognized that this objective was unattainable, without politically unacceptable changes in the rules of engagement.”175

A MACV study of the Easter offensive concurred with the Air Force findings and provides insight as to why Linebacker I did not have more impact on NVA operations.

The report noted that the NVA logistic reserves in South Vietnam had been stockpiled prior to the invasion. These stockpiles proved critical, enabling the NVA to weather shortfalls in resupply during the four to six weeks it took for Hanoi to adapt its supply routes from railways to roadways. As a result, the NVA was never forced to cancel or

172 HQ Seventh Air Force History of Seventh Air Force 1 July 1972 – 29 March 1973, Volume I AFHRA740.01-25 1 July 72 – 29 Mar 73, v1., 121. 173 HQ PACAF, CORONA HARVEST: USAF Air Operations in Southeast Asia 1 Jul 1972 – 15 August 1973 vII, IV -16. 174 Ibid., IV-81-82. 175 HQ PACAF, Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, V-3.

51 DRAFT: DO NOT CITE WITHOUT PERMISSION alter any of its major operations for lack of supplies.176 Such preparations neutralized the initial impact of Linebacker I, leaving it to air strikes in South Vietnam to block the resupply of NVA front line troops.

In sum, Linebacker I increased the costs and time for the North Vietnamese to send supplies to the South. With its men and weapons already deployed to South Vietnam and its stockpiles in place prior to the invasion, however, the NVA was able to transition from railway to dispersed road transport and negate the effects of the air interdiction campaign.

In contrast to the shortcomings of Linebacker I, the next section evaluates the role of CAS and BAI in bringing the Easter offensive to an end and compelling Hanoi to seek a ceasefire.

The Counter-offensive: Retaking Quang Tri

If the story of the fall of Quang Tri was one of the failure of air power to stem the

Communist advance, then the story of its recapture was one of adjustment to make air power decisive in the largest South Vietnamese counteroffensive of the war. Changes in

ARVN leadership, improved weather conditions, and the restoration of control and coordination mechanisms set the stage for a dramatic shift in the military balance in northern South Vietnam.

The replacement of General Lam with Lieutenant General Ngo Quang Truong after the fall of Quang Tri paid immediate dividends. Not content to secure the defense of Hue,

Truong instituted major changes in the organization and focus of I Corps. He recognized the control of air power and artillery fires as the key to both a successful defense and the eventual counter-offensive. To centralize and coordinate all U.S. and ARVN fires, he established a Fire Support Coordination Center (FSCC) as well as a Target Acquisition

176 HQ MAC-V, The Nguyen Hue Offensive MACDI Study 73-01 12 January 1973, A-1-3.

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Element to amplify the effectiveness of U.S. air strikes. Finally, Truong pushed

Vietnamese Tactical Air Control Parties (TACP) to the various Division headquarters in I

Corps to improve their capability to designate targets and control fires.177

Within two days of taking command, Truong initiated his first local offensives to stabilize the front and regain momentum. By mid-May, he had begun to launch multi- battalion airmobile and amphibious raids to keep the attacking NVA forces off balance.178

At the same time, Truong announced a program he labeled “Loi Phang” (Thunder

Hurricane):

“Loi Phang…was a sustained offensive by fire conducted on a large scale. The program scheduled the concentrated use of all available kinds of firepower, artillery, tactical air, Arc Light strikes, naval gunfire for each wave of attack and with enough intensity as to completely destroy every worthwhile target detected, especially those files of enemy personnel and materials that were streaming toward staging areas near Hue.”179

Whereas the NVA had used tanks, artillery, and speed to capture Quang Tri province in

April, Truong envisioned his coming offensive not as a blitzkrieg but a methodical and overwhelming application of firepower, particularly U.S. air power.180

Improving weather and enemy overextension amplified the effects of Truong’s attack by fire. Once the clouds had lifted in MR I, U.S. air power was free to hammer the artillery, staging areas, and supply lines in Communist-held Quang Tri province.181 As the

NVA units continued to attack in hope of seizing Hue, their offensive posture exposed them to ever increasing volumes of air, artillery, and naval gunfire.

177 Ibid., Truong, 53, 76. 178 Ibid., Andrade, 165, 170; ibid., Truong, 57. 179 Ibid., Truong, 54-55. 180 Ibid., Truong, 65. 181 Ibid., Lam Quang Thi, The Twenty-Five Year Century, 279; ibid., Truong, 76.

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By late June, Truong was ready to push north in force. Having received two elite units, the Vietnamese Marine Division and the Airborne Division, Truong was confident he could push from Hue toward Quang Tri. He opened the Lam Son 72 offensive on 28

June with elaborate deception operations and a two-day long air and artillery bombardment. The two divisions were able to drive north using B-52s and tacair to clear away the weakened remnants of the Communist units. In just over a week, Truong’s forces had reached the outskirts of Quang Tri City.182

This rapid advance stalled as it became clear that the Communists would try to hold Quang Tri at all costs. The NVA rotated elements of six divisions through Quang Tri in an effort to block the Airborne and Marine advance. Truong’s answer was to place the fresher Marine division in the lead and increase the volume of fires focused on the

Communist defenders. With the sieges at An Loc and Kontum largely resolved, the full weight of the B-52 force could now be brought to bear on Quang Tri. The overwhelming majority of the 3,407 B-52 sorties in South Vietnam in the month of August were directed to I Corps for this offense alone.183

On 8 September, after two months of bombarding the NVA defenses, Truong unleashed a final wave of air and artillery attacks before launching five battalions of

Vietnamese Marines against the Quang Tri Citadel. With the Marines fighting step by step through the rubble, the Communist defenders were driven out and the Citadel was retaken on 16 September. Over the last ten days of the battle, the NVA counted 2,767 dead while the ARVN Marines lost some 1,500.184

182 Ibid., MACV, Command History, Vol. I, 73. 183 Ibid., MACV, Command History, Vol. I, 70. 184 Ibid., Truong, 70-71.

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Why was air power more effective in the Lam Son 72 counteroffensive than in the defensive battles of April? Several factors stand out. The first is weather. The

Communists counted on bad weather to shield them from U.S. air power and, for the first weeks of the Easter Offensive, their hopes had been realized. The weather and dense air defenses negated many of the tacair and gunship capabilities the Americans might have otherwise employed in defense of the forward firebases. By May the weather had improved and, with it, the availability and utility of air power. Second, Truong and the

U.S. advisors reassembled a system to coordinate U.S. air power, artillery, and naval gunfire. Third, the enemy had broken itself in its bid to take Quang Tri and Hue. The losses suffered in the April attacks and even more under the stubborn insistence on maintaining the offensive in May and June tilted the balance in favor of the ARVN.

Fourth, the successful conclusion of the battles at An Loc and Kontum meant that the full weight of U.S. air power could be focused on a single, two-division attack in MR I.

Finally, Truong’s aggressive leadership and acute understanding of air power ensured that

CAS and BAI would be the centerpiece of his offensive.

Postwar North Vietnamese accounts underscore the impact of their own overextension and the massive amounts of U.S. firepower applied in MR I. In its conclusions on the Quang Tri offensive and ARVN counterattack, a 1987 Vietnamese

Ministry of Defense study emphasized the costs of underestimating U.S. CAS and BAI:

“The [ARVN] enemy’s situation had fundamentally changed. The puppet army had… moved up two mobile divisions from his strategic reserve forces, the Marine Division and the Airborne Division, and to these were added a large number of pieces of heavy technical equipment [heavy weapons] that directly participated in the battle. A point that requires special note and a full and adequate assessment is the direct participation of U.S. Air Force and the U.S. Navy fire support forces in large numbers to provide very intense and massive fire support (this was the heaviest amount of American firepower provided to support a single campaign in the entire history of the American

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aggression against South Vietnam, including even campaigns fought primarily by American ground forces; in terms of B-52s alone, during June 1972 the enemy flew an average of 135 B-52 bombing sorties per day, and more than 200 sorties on one day when the sortie level was the highest).”185

The history was equally emphatic about the costs of these mistakes to the NVA:

“We suffered heavy losses in six enemy counterattacks. Many of our units needed to be regrouped and reconstituted. We lost a large quantity of technical equipment and weapons but received no replacements for these losses (this was the phase in which we suffered our heaviest losses, larger than either of the two previous waves of attacks [30 March -9 April and 27 April -2 May respectively]).”186

As at Kontum, CAS and BAI almost singlehandedly blunted conventional offensives. But the transition to the offense demanded friendly infantry attacks and the casualties they entailed. The South Vietnamese Marines alone suffered 5,000 casualties in their three-month bid to retake Quang Tri. Air alone, even in immense volumes, could not root out the NVA defenders of the Quang Tri Citadel if the ARVN forces were unwilling to fight and die on the ground. At Kontum, and in even greater measure at Quang Tri, they were willing.187

Air power played a decisive role in the defeat of the NVA in the Easter Offensive.

The most compelling evidence of the impact of CAS and BAI comes from the U.S. advisors and North and South Vietnamese accounts. None of these groups had compelling interests in the bureaucratic struggles over the importance and proper employment of air power. All of them emphasized the role that tacair and particularly B-52s played in the defeat of the NVA in all three regions. On May 5, General Abrams captured this sentiment in his remarks to the MACV staff:

185 “The Tri Thien Strategic Offensive Sector, 1972,” Military History Institute of Vietnam/Ministry of Defense, Hanoi, 1987 (Translation by Merle Pribbenow), 173. 186 Ibid., “The Tri Thien Strategic Offensive Sector, 1972,” 174. 187 Ibid., Andrade, 196.

56 DRAFT: DO NOT CITE WITHOUT PERMISSION

“On this question of the B-52s and tac air, it’s very clear to me that – as far as my view on this is concerned – that this government would now have fallen, and this country would now be gone, and we wouldn’t be meeting here today, if it hadn’t been for the B-52s and the tacair. There’s absolutely no question about it.”188

In strikingly similar terms, a 1976 internal, classified North Vietnamese history of the

Quang Tri Offensive acknowledged the singular role of air power in upsetting the

Communist advance:

“During combat, with the increased American fire support, the puppet was able to erode our troop strength and equipment levels to a greater extent, increasing the ferocity and complexity of the battle and having an enormous impact on the combat strength of our troops. In practical terms, the intensity of U.S. firepower, which had been reinforced to the highest level possible, had a decisive impact and rescued the puppet army from complete collapse. Although we anticipated that the United States might resume bombing, we did not fully anticipate the capabilities and the full impact U.S. air and naval firepower would have on the progress of the campaign. For that reason our assessments of the puppet army were sometimes subjective, simplistic, one-sided, and not in tune with the developing situation, and sometimes our battle plans were not sufficiently based on reality….”189

LTG Truong, the savior of ARVN fortunes in MR I, was equally adamant about the impact of U.S. air power in the outcome of the offensive:

“The role of the U.S. Air Force was decisive in several instances. The support provided by U.S. tactical air and the B-52s on all major fronts was timely and most effective; it not only destroyed many enemy formations but also sustained the morale of the ARVN soldiers. If laudatory words are used here to describe the U.S. Air Force’s contributions to the RVNAF success in repelling the enemy’s biggest offensive to date, they certainly should not be construed as flattery…. Quang Tri certainly could not have been retaken, nor could ARVN forces have held at Kontum and An Loc, had it not been for the support provided by the U.S. Air Force…. The only adverse effect that can be attributed to the use of B-52s was that in time, ARVN forces became too dependent on them.”190

188 Ibid., Sorley (ed.), Vietnam Chronicles, 833. 189 “The 1972 Quang Tri Offensive Campaign, (Secret)” [Chien Dich Tien Cong Quang Tri 1972, Mat], Military Art Faculty of the Military Science Institute, Hanoi, 1976, 76 [NOTE: In addition to being marked “Secret” [Mat], this document is also marked “Document for Internal Distribution Only” [Tai Lieu Luu Hanh Trong Noi Bo]. (Translation by Merle Pribbenow) 190 Ibid., Truong, 172.

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The effective use of CAS and BAI in the Easter Offensive hinged on the control and coordination of those fires. The combination of U.S. ground advisors, U.S. FACs, and the U.S. administered TACS made possible the victories at An Loc, Kontum, and the retaking of Quang Tri. The absence of a functioning, U.S. TACS in MR I played a large role in the failure of air power in the north in opening month of the offensive.

Without U.S. air support, it is hard to imagine a successful ARVN defense in MR

I, II, or III. With it, the defeat of the Easter Offensive was possible and that outcome left the Communists with few alternatives to a negotiated settlement. This, in turn, brought the North Vietnamese to accept the “peace with honor” terms necessary to prompt the

U.S. to decide to withdraw its forces from Vietnam. It was not, however, Linebacker I’s air interdiction campaign in North Vietnam that was decisive; rather, it was U.S. air power’s direct attack of the NVA fielded forces and forward supplies in the South that allowed the ARVN to hold at An Loc and Kontum and that turned the tide at Quang Tri.

The October Agreement, Linebacker II, and the January 1973 Paris Peace Accords

The ARVN’s recapture of Quang Tri in September caused Hanoi to seek a diplomatic solution to terminate the U.S. military presence in Vietnam. According to

American-Vietnamese historian Lien-Hang T. Nguyen:

“Only after his military plans failed with the ARVN’s recapture of Quang Tri City did Le Duan accept that the diplomatic struggle had to prioritize ‘American troop withdrawal’ first and foremost.”191

On 8 October 1972, North Vietnamese foreign minister Le Duc Tho met with

Henry Kissinger in Paris and announced that Hanoi was now willing to negotiate a cease- fire which allowed for North Vietnamese troops remaining in South Vietnam, a

191 Nguyen, 270.

58 DRAFT: DO NOT CITE WITHOUT PERMISSION withdrawal of U.S. forces from Vietnam, and the repatriation of U.S. POWs.192 Le Duc

Tho’s terms, which no longer mentioned as a precondition the removal of the South

Vietnamese government, were the same proposed by Nixon in May to settle military issues while leaving a political solution for later.193 By 18 October, Tho and Kissinger had settled on the specific terms of the agreement and on 26 October, Kissinger proclaimed “peace is at hand.”194 Saigon, however, had been excluded from the talks.

President Nguyen Van Thieu was first made aware of the specifics of the deal in late

October. He refused to sign any agreement allowing North Vietnamese forces to remain in the South, a stance which led to a three-month delay to the peace deal and another round of Linebacker bombings.

Nixon took no action, however, until after the November presidential election. By then North Vietnam, feeling duped by the Americans, had begun to wonder about the degree of control the White House had over Saigon. When further negotiations in Paris went nowhere, Nixon ordered Linebacker II to start just before Christmas. Meanwhile, to assuage Thieu, Nixon promised billions in military aid, along with assurances that the

United States would punish North Vietnam for any infractions to the peace treaty. Nixon also issued an ultimatum that if Saigon did not sign, the United States would withdraw and cut off all military support.195

192 Kissinger, White House Years, 1343. 193 Kissinger, 1345. 194 Kissinger, 1355; Asselin, Pierre A Bitter Peace, (Chapel Hill, NC: University of North Carolina Press, 2002) Appendix A, 191-201. New York Times “Kissinger Asserts That ‘Peace is at Hand’; Saigon says it will agree to a Ceasefire” 26 October 1972, 1. 195 Kissinger, 1459-60.

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Linebacker II consisted of eleven nights of air strikes highlighted by B-52 attacks on rail yards, power plants, and airfields in Hanoi and Haiphong Harbor.196 The USAF lost fifteen B-52s to North Vietnamese SA-2s in the process. By the tenth night of bombing, the North Vietnamese had run out of surface-to-air missiles to defend their skies. On December 28, Hanoi indicated a willingness to resume talks. Nixon ordered a bombing halt the next night, and talks resumed in early January. By 27 January 1973, the

Paris Peace Accords were signed. The terms were identical to the October agreement except, to appease Thieu, the name the North Vietnamese had given to their troops remaining in South Vietnam, the Provisional Revolutionary Government of the Republic of South Viet-Nam, had been removed from the main text of the document and appeared only on one of the signature pages.197 The United States and South Vietnam signed one signature page while North Vietnam and the Provisional Revolutionary Government signed another.198

Whereas Linebacker I had been ineffective in coercing Hanoi, Linebacker II did compel the North Vietnamese to return to Paris but only to sign the peace agreement they had already agreed to in October. It was, rather, U.S. air power employed as CAS and

BAI in coordination with ARVN ground forces that defeated the NVA in the Easter

Offensive that had convinced Hanoi to seek the peace deal in the first place.

196 For operational details of Linebacker II see Marshall Michel, The Eleven Days of Christmas (San Francisco: Encounter Books, 2002) 197 The exact wording for the two agreements are given in full in Appendix A and B of Piere Asselin’s A Bitter Peace 198 Asselin, Appendix B, 214.

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CONCLUSION

U.S. close air support and battlefield air interdiction broke the North Vietnamese

Army in the Easter Offensive. With its army decimated, the North Vietnamese had no immediate alternatives to accepting a U.S. peace deal. Still, the myth of Linebacker I and

II endures. Despite the fact that the interdiction campaign in North Vietnam did not have a significant impact on the NVA’s campaign in the South, and the Christmas bombing of

Hanoi succeeded only in bringing the North Vietnamese back to Paris to sign an agreement to which they had previously agreed, most observers have ignored the contributions of the larger, more effective, and more consequential direct attack on the

Communist armies. In the south, U.S. ground advisers working with a U.S.-operated tactical air control system (TACS) enabled the South Vietnamese army to halt, cripple, and eventually roll back the NVA. This U.S. advisory mission, led by a handful of U.S.

Army and Air Force liaison officers, coordinated and controlled the thousands of tactical fighter-bomber sorties, B-52 Arc Light strikes, and fixed- and rotary-wing gunship missions which proved decisive.

We suspect that this bias in the existing historiography is more than accidental.

The U.S. Air Force has had little institutional incentive in telling the story of how independent air operations in North Vietnam failed while CAS and BAI succeeded.

Likewise, the U.S. Army has had little to gain by emphasizing how the largest battle of the

Vietnam War was won not by U.S. ground troops but by a weak ally supported by a handful of U.S. military advisers and air liaison officers.

While these conclusions are important revisions to our understanding of the

Vietnam War, the contemporary implications of the Easter Offensive are both intriguing

61 DRAFT: DO NOT CITE WITHOUT PERMISSION and more complex. On the one hand, the air offensives of 1972 offer a rare opportunity to examine competing theories of victory for air power. Our most important conclusion is that these air campaigns demonstrate the superior and enduring effectiveness of CAS and

BAI relative to interdiction and strategic attack.

On the other hand, any findings based on a single historical episode are at best propositions; the generalizability of these lessons to contemporary cases depends on the answers to two questions: How representative was the 1972 Easter Offensive of the challenges militaries might face in the 21st century? How have changes in technology over the intervening forty years altered the ways in which air power works in practice – specifically the balance between CAS/BAI and interdiction/strategic attack?

We argue that the functional challenges of 1972 continue to dominate U.S. military planning in the 21st century. Over the past two decades, in Afghanistan, Iraq, and elsewhere, the U.S. has had to decide how best to apply air power in support of allied armies of mixed quality. Many of those allies have faced conventional or quasi- conventional attacks by enemies with substantial troop formations and vehicles. In many instances, the United States has been unwilling to commit large numbers of American combat troops and decision makers have seen the employment of air power as a less risky and more flexible alternative to ground intervention. America’s allies have shared many of the weaknesses of the South Vietnamese armed forces; even after years of U.S. training, many allied armies struggle to coordinate air strikes, artillery, and logistics without extensive advisory support.199 Under these circumstances, the United States has been

199 General Joseph Dunford, Jr., “Hearing to receive testimony on the situation in Afghanistan,” U.S. Senate, Committee on Armed Services, Wednesday March 12, 2014, http:///www.armed- services.senate.gov/imo/media/doc/14-19%20-%203-12-14.pdf; Jonathan Schroden (et al.), “Independent Assessment of the Afghan National Security Forces,” Center for Naval Analyses, February 20, 2014, pp. 39-

62 DRAFT: DO NOT CITE WITHOUT PERMISSION forced to allocate scarce air assets and weigh the costs and benefits of U.S. advisory support on the ground and in the air.

While it is true that there have been substantial changes in technology over the intervening four decades, we contend that developments in precision weaponry, sensors, and air defenses have not altered the balance of effectiveness between CAS/BAI and interdiction/strategic attack. Increasing precision and sensor developments have simplified the problems of finding and hitting targets; improved air defenses have increased the cost and risk of applying air power with manned platforms. Precision strike has enhanced the effectiveness of air power across the range of missions while it has done little to alter the balance between direct support and deep attack. The risk in confronting enemy air defenses continues to be a function of exposure; all things being equal, deep attacks, whether for interdiction or strategic attack, expose aircraft to a greater aggregate risk than operations near the frontlines.

None of these technological changes have resolved the underlying conceptual challenges of translating target hits into effects and accounting for enemy adaption.

Instead, elemental questions remain. If the goal is to stop or roll back an enemy ground invasion, is it more effective to attack the enemy’s army in the field or to cut supply lines and attack strategic targets to the enemy’s rear? What can a thinking opponent do to limit the effects of air power in the form of CAS/BAI or interdiction/strategic attack?

Today, as in Vietnam, we argue that interdiction is a siren song -- conceptually appealing but generally unrewarding. Interdiction tends to be most effective against armies on the move; mobile offensive and defensive operations increase the enemy’s

40, 149, www.cna.org/sites/default/files/research/CNA%20Independent%20Assessment%20of%20the%20ANSF.pdf

63 DRAFT: DO NOT CITE WITHOUT PERMISSION demand for supplies and with them the enemy’s vulnerability to interruption. Even under these circumstances, however, interdiction tends to be indecisive. The enemy can use stockpiling to limit its vulnerability to interdiction; if interdiction begins to take a serious toll, the enemy can reduce the tempo of its operations to match the available stockpiles and logistical flow. Furthermore, most enemies adapt to interdiction by developing alternative supply routes to bypass primary road and rail networks. Finally, the air planner uniformly struggles to determine the enemy’s future breaking point. In a cumulative campaign, it is easier to count the number of targets struck than to estimate how many additional strikes will be necessary to force political concessions or enemy collapse.

Direct attack on an enemy’s army, by contrast, is simpler, more effective, and less costly. By breaking armies with CAS and BAI, military planners deny their enemies the tools they need to accomplish their ends. The effectiveness of CAS and BAI is more closely linked to target destruction; by contrast, interdiction and strategic attack hinge on the material and psychological effects of target destruction on enemy decision-making. In this sense, our findings support and sharpen Robert Pape’s contention that denial strategies are superior to punishment strategies.

Recent U.S. experiences in Iraq and Afghanistan support these conclusions.200 In the first Gulf War of 1990-1991, an interdiction campaign was pointless as the Iraqi Army had already deployed its forces and stockpiled supplies before the air war commenced.

Likewise, U.S. strategic bombing neither decapitated Saddam Hussein’s regime nor paralyzed the Iraqi Army as air planners had hoped. Instead, it was the combined direct attack of Iraqi forces and the threat of the impending ground invasion that convinced Iraq

200 For U.S. air power against Iraq in 1991 see Pape, Chapter 7; For Afghanistan see Benjamin S Lambeth, Air Power Against Terror: America’s Conduct of Operation Enduring Freedom (Santa Monica, CA: Rand, 2005; For Iraq 2003 see Michael Knights, Cradle of Conflict (Annapolis, MD: Naval Institute Press, 2005).

64 DRAFT: DO NOT CITE WITHOUT PERMISSION to offer to withdraw from Kuwait. And when the United States refused to accept Iraq’s concession the ensuing ground war was a rout as Iraqi forces, dispersed and attrited by air power, could not resist coalition ground forces.

In the 2003 Iraq War, strategic attack failed to decapitate Saddam’s regime and air interdiction was again not even attempted. Instead, Saddam ordered the concealment and dispersal of his forces against the air campaign he anticipated, making the U.S. Army and

Marine Corps march to Baghdad, a relatively brief and low casualty affair. In

Afghanistan, the earliest U.S. air strikes against such strategic targets as government facilities and training camps were ineffective. Only after U.S. air power shifted from strategic targets to frontline targets designated by joint tactical air controllers embedded in special operations teams on the ground did the Taliban armies collapse.201 Here as in

Vietnam, air power opened a breach that an allied army could then exploit. Emboldened by the precise application of air strikes, the Northern Alliance surged south to seize Kabul and topple the Taliban regime. Once again, the critical ingredients were small teams of

U.S. advisers providing target coordinates and final control for CAS.

The tepid results of U.S. air operations in Libya and post-transition Afghanistan and Iraq can be traced to these same variables. The absence of U.S. ground observers and other elements of the control system severely limited the effectiveness of U.S. air strikes in all three cases. U.S. leaders have been understandably reluctant to approve air strikes in close proximity to allied forces when they do not trust the ability of the locals to identify and classify targets and control for collateral damage. These shortcomings have led to

201 Gary Schroen, First In: An Insider’s Account of How the CIA Spearheaded the War on Terror in Afghanistan (Ballantine Books, 2005), 154-155, 161, 185, 304-305; Henry Crumpton, The Art of Intelligence: Lessons from a Life in the CIA’s Clandestine Service (New York: the Penguin Press, 2012), 217-219; Benjamin Lambeth, Air Power Against Terror: America’s Conduct of Operation Enduring Freedom (Santa Monica: RAND Corporation, 2005), MG-166, 79-84, 106, 121, 125-128.

65 DRAFT: DO NOT CITE WITHOUT PERMISSION calls for the reintroduction of the small U.S. advisory and control elements that proved so critically important in Vietnam in 1972 and Afghanistan in 2001-2002.202

This finding has significant implications for U.S. military procurement and doctrine. USAF acquisition has long favored deep strike over CAS and BAI. For the past thirty years, the Air Force has prioritized the development of stealth aircraft designed to penetrate sophisticated enemy air defenses for the purpose of conducting strategic attack, air interdiction, or establishing air superiority. The enormous procurement costs associated with these complex aircraft has crowded out not only the resources to maintain existing CAS and BAI platforms, but also any efforts to develop the next generation of aircraft capable of surviving and operating in forward areas.

The Air Force has compounded this misallocation of resources toward deep strike and away from direct attack by removing BAI from its doctrine. Twice it has eliminated

BAI as a separate mission, first during the major conventional battles by the U.S. Army in

South Vietnam in 1966, and again in 1991 in the first Gulf War.203 Instead, the Air Force treats the BAI mission as a subset of air interdiction.204 This doctrinal change has profound implications. It obscures how air power actually works by assuming the requirements to locate and attack enemy forces on the battlefield are similar to those required to indirectly attack those forces by interdicting their lines of communication.

This blurring of missions has led to major errors as air power theorists and historians have mistakenly lumped the Linebacker I air interdiction campaign in North Vietnam into the

202 Michael Gordon, “U.S. Weighs Training Iraqis to Call in American Airstrikes in ISIS Fight,” The New York Times, April 23, 2015; Margherita Stancati, Natahn Hodge, “Kabul Combats New Taliban Offensive, The Wall Street Journal, April 30, 2015, A7. 203 For history of Air Force doctrine with regards to BAI see Terrance McCaffrey, What Happened to Battlefield Air Interdiction? (Montgomery, AL: Air University Press, 2004) 204 Annex 3-03 Counterland Operations, 14 April 2014, https://doctrine.af.mil/download.jsp?filename=3- 03-D05-LAND-Interdiction-Fun.pdf accessed 23 March 2015.

66 DRAFT: DO NOT CITE WITHOUT PERMISSION same category as the BAI airstrikes in South Vietnam.205 The Air Force should reintroduce BAI into its doctrine alongside CAS as direct attack missions aimed at defeating an enemy’s military capability.

Together, the procurement priority given to deep strike and doctrine which undervalues direct attack threatens to reduce the effectiveness of American air power. The most important elements in CAS and BAI have always been the small number of highly trained personnel manning the aircraft, TACS, and ground advisory teams. Their effectiveness is a function of specialization and preparation. The Air Force’s preference for sophisticated, multi-role aircraft, and the elimination of BAI from doctrine have diminished the amount of time and resources devoted to the development and maintenance of the skills necessary to carry out air strikes in close proximity to friendly troops.

Ironically, the battle over platforms is less significant than the unintended, second order effects that such procurement decisions have on the readiness of aircrews to conduct CAS and BAI, particularly in support of allied ground forces. The real impact of a move from

A-10s to F-35s is the dilution of CAS and BAI skills and a commensurate reduction in

U.S. effectiveness in the highest yield air missions.

Our second main finding recognizes the centrality of the air control system. Such a system is more important than having specialized aircraft, sensors, and precision weapons to engage enemy forces. These weapons systems will be ineffective unless their firepower can be coordinated and controlled on the battlefield and integrated with allied ground operations. The relatively ineffective direct attacks the United States on Serbian forces in Kosovo in 1999 were the result of its inability/unwillingness to integrate its air

205 Pape, 199. Farquhar, John, “The United States Air Force Historical Perspective” in Airman AF Handbook I (USAF, 2007), 68.

67 DRAFT: DO NOT CITE WITHOUT PERMISSION strikes with the operations of the Kosovo Liberation Army.206 A similar lack of integration in the Libyan Civil War in 2011 likewise extended the conflict for months. By contrast, the effective integration of air and ground forces in Afghanistan in 2001-2002 made possible a quick and decisive outcome.

The backbone of the U.S. air control system is the small cadre of trained ground advisors, air liaison officers, observers, and tactical air controllers. Even a modest number of skilled personnel, supported by a moderately capable army, can halt or even roll back larger armies. For CAS and BAI to be effective in contemporary cases such as the campaign against ISIS, the United States must, at a minimum, deploy small numbers of ground advisors, air liaison officers, and controllers.207 While the past fourteen years of conflict have created a pool of experienced and qualified personnel, there is no guarantee that these capabilities will be maintained by the services. As budgets fall and the armed forces must cut capabilities, bureaucratic pressures within and between services will tend to squeeze out these niche capabilities in favor of preferred, if problematic, mission sets such as interdiction and strategic attack. While retaining specialized personnel and maintaining their proficiency and manning, has not historically been a high priority for any of the services, it is vital to air power success. It is often the difference between

“blowing up trees” and battlefield victory.

The experience of the 1972 Easter Offensive suggests that client states can defeat much larger enemy forces in major conventional battles even if their armed forces lack the

206 Daniel R. Lake “The Limits of Coercive Airpower: NATO’s ‘Victory’ in Kosovo Revisited” International Security 34: 1 (2009) 207 Under certain conditions, such as with NATO operations, a TACS need not be supported solely by U.S. soldiers and airmen. However, as seen at Quang Tri during the Easter Offensive, and today with long-term allies such as South Korea, the communication requirements for operating a functioning TACS are high and may not be achievable without the integration of American personnel.

68 DRAFT: DO NOT CITE WITHOUT PERMISSION proficiency of modern great powers. But air power is only likely to succeed if the United

States military has the doctrine, assets, and training to conduct effective close air support and battlefield air interdiction. This is only likely, however, if a competent, U.S.-run, tactical air control system is present: ground advisors, air liaison officers, observers, forward air controllers, and the associated air control networks. These small and seemingly niche capabilities may be the key to making small footprint, advisory missions effective; the maintenance of these communities and capabilities in an era of defense cuts may be the difference between effective defense and the collapse of allies.

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