FM 5-100-15: Corps Engineer Operations
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FM 5-100-15 PREFACE This field manual (FM) is a guide for the employment of engineer forces in support of a United States (US) Army corps. It addresses the role, organization, and command and control of corps engineers and the conduct of corps-level engineer operations. The primary users of this FM are the corps commander and his staff, the corps engineer and his staff, engineer units subordinate to the corps engineer brigade, and theater engineer organiza- tions at echelons above corps (EAC). Other users will be engineer organizations supporting maneuver units subordinate to the corps and sister serviced commanders and staffs, the United States Army Corps of Engineers (USACE), and government contractors. The manual is fully compatible with the Army’s operational doctrine as contained in FMs 100-5 and 100-7 and is consistent with current joint and multinational doctrine. This manual follows the format of FM 100-15 and supports the concepts and principles contained therein. It also complements FMs 5-71-100 and 5-116. The proponent for this publication is the United States Army Engineer School (USAES). Submit changes for improvement on Department of the Army (DA) Form 2028 (Recommended Changes to Publications and Blank Forms) to Commandant, US Army Engineer School, ATTN: ATSE-T-PD-PM, Fort Leonard Wood, Missouri, 65473-6650. Unless this publication states otherwise, masculine nouns and pronouns do not refer exclusively to men. ix FM 5-100-15 CHAPTER 1 CORPS ENGINEER OPERATIONS The objectives of the carpet-bombing effort in front of the VII Corps were to mask the assault and saturate enemy defensive sectors as far back as their direct-support artillery positions. Following the bombing, the 1st, 9th, and 30th Infantry divisions were to deliver a coordinated assault across a relatively narrow front and punch a hole through which the waiting 2nd and 3rd Armored divisions would launch a pursuit of the presumably routed German forces. The 1106th Engineer Combat Group was moved up to the VII Corps’ left flank to support directly the 30th Infantry Division and the initially trailing 2nd Armored Division as they advanced along high ground on the west bank of the Vire River. On the VII Corps right flank, the 1120th Engineer Combat Group would support the 4th and 9th Infantry divisions in the assault and the follow-on 3rd Armored Division in the pursuit. Our own 1111th Engineer Combat Group would act as the corps engineers in the VII Corps sector, devoting its efforts to opening and maintaining the supply routes and building and maintaining the longer, more permanent timber trestle bridges back along the MSR that would be opened by the advancing infantry and armor and initially cleared by the direct-support engineer combat battalions. A description of Army breakout plans from the Normandy lodgment in July 1944. From the book, The First Across the Rhine, The Story of the 291st Engineer Combat Battalion. by Colonel David E. Pergrin with Eric Hammel. THE ROLE OF CORPS ENGINEER FORCES THE CORPS erations for a considerable period. During force-projection operations, an Army corps may The corps is the US Army unit capable of oper- serve as the Army forces (ARFOR) headquar- ating at both the tactical and operational levels ters to a theater command or joint task force of war. It is the instrument by which higher (JTF) or as a JTF headquarters itself. The echelons of command conduct maneuvers at the corps may control units from the Air Force, operational level. Corps are tailored based on Navy, and Marine Corps, along with allied and mission, enemy, terrain, troops, and time avail- coalition nations. A tailored corps engineer bri- able (METT-T) to contain all combat, combat gade is commonly available to the corps to support (CS), and combat service support weight its main effort and to perform special (CSS) unit capabilities required to sustain op- CS functions. Corps Engineer Operations 1-1 FM 5-100-15 THE CORPS ENGINEER BRIGADE also tasks and prioritizes the work effort of the DS corps topographic company. The corps engineer brigade commands and con- trols all engineer support to the corps and is In force-projection theaters where no forward- assigned all engineer units that are not organic based theater engineer structure exists, the to divisions, separate maneuver brigades, and corps engineer brigade could initially function cavalry regiments. The brigade provides mo- as the theater engineer headquarters and re- bility countermobility survivability, and gen- gional contingency engineering manager eral engineering support to the corps based on (RCEM). To do this, the brigade needs special METT-T. Corps topographic engineering sup- augmentation from an engineer command port normally is provided by a topographic en- (ENCOM) and/or the USACE in the areas of gineer company placed indirect support (DS) to construction management, real estate acquisi- the corps from the theater Army (TA) topo- tion, and construction contracting support. graphic engineer battalion. The corps engineer The brigade would execute this function until brigade augments engineers organic to divi- an ENCOM, TA. engineer brigade, or engineer sions, separate maneuver brigades, and cav- construction group arrives in theater. alry regiments. In the absence of follow-on deployment of an The corps engineer brigade may contain vari- ENCOM, TA engineer brigade, or engineer con- ous numbers of engineer groups, corps engi- struction group, the corps engineer brigade neer battalions (mechanized, wheeled, air- (with the special augmentation listed above) borne, and light), combat heavy engineer bat- may have to act as the theater engineer head- talions, and separate engineer companies quarters indefinitely. (fixed and assault float bridge, combat support equipment (CSE), light equipment (LE), and SIMULTANEOUS OPERATIONS topographic). Other specialized engineer or- ganizations will augment the corps engineer Simultaneous deep, close, and rear corps op- effort as the mission dictates. The brigade con- erations comprise a special and continuous trols and staff supervises theater engineer battle space synchronization requirement. forces from EAC operating in the corps area. The linkage between these operations assures These may include units such as prime-power that the aims, timing, and activities associated battalions; construction support, pipeline con- with these operations are mutually supporting. struction, dump truck and port construction For commanders, synchronization of simulta- companies; and utilities, well-drilling, fire- neous operations will normally require deliber- fighting, and other special teams and detach- ate planning and staff coordination. Simulta- ments. neous operations in depth have a direct impact on the enemy's cohesion. Corps units are no The corps engineer brigade commander also longer restricted to fighting three sequential serves as the corps engineer special staff offi- operations (deep, close, and rear). Nor are in- cer. The corps staff engineer section (SES) as- depth operations conducted solely to establish sists him by providing engineer functional- favorable conditions for the close fight. The area expertise to all corps stiff elements. The corps commander influences these operations SES provides recommendations to the corps by assigning on-order missions and priorities staff on the use of engineer assets and ensures and allocating combat assets. He must de- that the engineer battlefield functions are fully scribe, in his concept of the operation, how all planned, integrated, synchronized, and exe- deep, close, and rear operations will be exe- cuted to support the corps commander’s intent cuted simultaneously, their command rela- and scheme of maneuver. The corps engineer tionships, and their relative priorities. The 1-2 Corps Engineer Operations FM 5-100-15 corps commander will retain reserve forces un- phase of deep operations, engineers provide ter- der his control. The command echelon above rain analysis that supports the identification of corps designates the corps’s area of operations named areas of interest (NAIs) and target ar- (AO). The corps geographically divides its AO eas of interest (TAIs). Countermobility targets into subareas where it will conduct close, deep, are recommended for nomination by corps staff and rear operations. The use of lateral, rear, engineers to the corps Assistant Chief of Staff, and forward boundaries is intended to better G2 (Intelligence) (G2)/Assistant Chief of Staff, delineate responsibility and commandant con- G3 (Operations and Plans) (G3) deep opera- trol (C2). However, combat operations in the tions coordination cell and the corps’s joint tar- geting board. Recommended targets for nomi- corps area may be nonlinear, and the intermin- nation could include the emplacement of long- gling of opposing forces may be inevitable. The range scatterable minefield and the destruc- air and space above the corps’s AO constitute a tion of bridges and other choke points. The use third dimension of the corps’s battle space. of deep countermobility emplacement systems, such as the Gator, needs to be planned and Corps engineers support operations through- coordinated at least 72 hours prior to delivery out the corps’s battle space based on the corps time. commander’s intent and METT-T. Engineer support to all corps deep, close, and rear op- The Detect phase executes the decisions erations focuses on planning, coordination, reached in the Decide phase. When target synchronization, integration, and resource al- selection