FM 7-15 INFANTRY FIELD MANUAL ! HEAVY WEAPONS COMPANY COM- PANY, RIFLE REGIMENT UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1942 1 WAR DEPARTMENT WASHINGTON, May 19, 1942 FM 7-15, Infantry Field Manual, Heavy Weapons Com- pany, Rifle Regiment, is published for the information and guidance of all concerned [A. O. 062.11 (4-18-42).] BY ORDER OF THE SECRETARY OF WAR: G. C. MARSHALL Chief of Staff. OFFICIAL: J. A. ULIO. Major General, The Adjutant General. DISTRIBUTION: D 7 (2); R 7 (2); Bn 7 (5); IC 7 (20). (For explanation of symbols see FM 21-6.) 2 TABLE OF CONTENTS Paragraphs CHAPTER 1. General SECTION I. Composition, armament, and equipment… 1-6 II. Tactical employment of heavy weapons 7-8 company…………………………………... CHAPTER 2. Marches and bivouac……………………….. 19-24 CHAPTER 3. Offensive combat SECTION I. General…………………………………………. 25 II. Approach march………………………….. 26-29 III. Reconnaissance prior to attack, and 30-33 orders………………………………….. IV. Attack………………………………………. 34-44 V. Night attack……………………………….. 45-47 VI. Raids………………………………………… 48 VII. Attack in woods…………………………… 49-51 VIII. Attack of towns and villages…………… 52 IX. Attack of river line……………………….. 53-55 CHAPTER 4. Defense and retrograde movements…. SECTION I. Reconnaissance, organization of fires, 56-70 and conduct of defense……………. II. Retrograde movements…………………. 71-72 III. Defense in woods………………………… 73 IV. Defense in towns and villages………… 74 V. Defense of river line…………………….. 75 VI. Defense against air-borne operations.. 76 CHAPTER 5. Caliber .30 machine gun platoon…….. SECTION I. General……………………………………... 77-81 II. Attack……………………………………….. 82-99 III. Defense………………………………….. 100-119 CHAPTER 6. Caliber .30 machine gun section and squad SECTION I. General…………………………………... 120-126 II. Attack…………………………………….. 127-142 III. Defense………………………………….. 143-152 CHAPTER 7. 81-mm mortar platoon SECTION I. General…………………………………... 163-158 II. Attack…………………………………….. 159-176 III. Defense………………………………….. 177-194 CHAPTER 8. 81-mm mortar section and squad SECTION I. General…………………………………... 195-202 II. Attack…………………………………….. 203-217 III. Defense………………………………….. 218-231 CHAPTER 9. Administration SECTION I. Supply……………………………………. 232-241 II. Medical service and evacuation……. 242-245 III. Motor maintenance……………………….. 246 CHAPTER 10. Signal communication 247-251 APPENDIX I. Individual protection; emplacements 200 for heavy machine guns and 81- mm mortars; observation posts; and hints on camouflage…………… 3 FM 7-15 INFANTRY FIELD MANUAL HEAVY WEAPONS COMPANY, RIFLE REGIMENT CHAPTER 1 GENERAL SECTION I COMPOSITION, ARMAMENT, AND EQUIPMENT ! 1. COMPOSITION.—a. Company.—The heavy weapons Since most reenactors have never company consists of a company headquarters, two caliber seen a cal. .30 heavy machine .30 heavy machine-gun platoons, and one 81-mm mortar gun or an 81-mm mortar, they platoon. (See fig. 1.) For details of organization, armament, seldom take these things into con- and equipment, see Tables of Organization and Table of sideration. This results in a serious Basic Allowances. misconception about the types and uses of firepower on the bat- b. Company headquarters.—(1) The company head- tlefield. These two weapons – quarters is composed of a command group and an ad- particularly in the defense – pro- ministration group. vide a huge force multiplier. Many of the operations described for the (2) The command group consists of the company battalion and regiment could not commander, reconnaissance officer, first sergeant, recon- be undertaken without the support naissance and signal sergeant, transport sergeant, motor of the heavy weapons company. mechanics, bugler, orderly, and messengers. Chauffeurs who drive the command trucks assigned to company Keep in mind that the regiment headquarters, and basic privates, are included in the has three such companies, desig- command group. nated D, H, and M. (3) The administration group consists of the supply sergeant, mess sergeant, cooks and cooks' helpers, ar- morer artificer, and the company clerk. c. Platoons.—For composition, refer to figure 1 and see paragraphs 78 and 154. ! 2. CAPABILITIES AND LIMITATIONS OF HEAVY MACHINE GUN.—The caliber .30 heavy machine gun is a crew-served The “heavy” – many reenactors weapon capable of delivering a large volume of continuous confuse this with the M2 cal. .50 – fire. Medium rate of fire (125 rounds per minute) can be is by design not much different sustained indefinitely. Rapid fire (250 rounds per minute) from the “light” version. The heavy can be fired for several minutes, but steaming will occur has two advantages: the water Within 2 or 3 minutes. Because of its fixed mount, the jacket that allows a much greater heavy machine gun is capable of delivering overhead fires sustained rate of fire by retarding barrel overheating, and a heavy and of firing accurately at night from predetermined data. mount that permits accurate fire at Due to the length of the beaten zone (horizontal pattern of long range. This means the maxi- dispersion) enfilade fire is the most effective type of fire mum range is the same as for the delivered by this weapon. When overhead fires are not light version, but the max effective possible or desirable, fires are directed through gaps range is much longer. 4 between riflemen or groups of riflemen. Gaps may be cre- Bear in mind, however, that the ated and maintained for such fire. ballistic trajectory of the heavy is identical to the light version. This means that the bullets fly in a high arc at longer ranges, resulting in “plunging” fire – bullets are zipping from above rather than snapping along a foot or two above the ground as with “grazing” fire. At best, the combination of long- range plunging fire and grazing fire from the flanks can ruin the enemy’s day. The price to be paid, however, is the weight of the HMG (it isn’t called “heavy” for nothing) and the need to refill the water jacket as the water boils off (taking barrel heat with it – thermodynamics is a bitch). The weapons carriers earn their name. a. Mobility.—After being removed from its weapon carrier, the heavy machine gun and its crew have the same sus- tained mobility for a considerable distance as have rifle- men. Eventually, however, fatigue will cause the crew to fall behind, beyond supporting distance. Hand-carry of ammunition for distances much in excess of 500 yards greatly increases the problem of maintaining an adequate supply of ammunition at the gun. Weapon carriers must be used, therefore, to the limit of their capabilities in transporting the machine guns and supplying them with ammunition. See limitations on the use of weapon carri- ers, paragraph 6b (2). b. Ranges.—(1) The effective range of the machine gun, You will often not be able to see employing direct fire, is limited by observation. Observa- the target, so the firing tables are tion will rarely be effective beyond 2,000 yards. necessary to set the correct eleva- tion. Note also that tracer rounds (2) The effectiveness of the machine gun, employing will help the gunner and observer indirect fire, is limited by its maximum effective range and sense fall of rounds. by the facilities for obtaining accurate firing data. (See FM 23-45 and 23-55.) c. Vulnerability.—An enemy will search for the location of machine guns. The distinctive noise of firing, the muzzle blast, dust clouds caused by firing, and the silhouette of the gun, all tend to disclose its location. Therefore, firing positions should, whenever practicable, be selected in po- sition defilade or partial defilade. See paragraph 25b (3) and figures 7, 8, and 9. When time permits, the machine gun should be well dug in. For machine-gun emplace- ments, see appendix I and figures 28, 29, and 30. d. Targets.—The hostile target most dangerous, at the moment, to friendly troops is the primary target. Suitable targets are- (1) Exposed personnel, particularly if in close forma- tion, or in depth with respect to the line of fire. 5 (2) Intrenched personnel, observation posts, ma- chine guns, or antitank guns, for destruction or neutrali- zation. Neutralization is accomplished by hampering or interrupting movement or action, and thereby reducing or destroying the combat efficiency of the target. (3) Low-flying airplanes. The effective slant range of heavy machine guns against low-flying airplanes does not exceed 1,000 yards. For antiaircraft fires, see paragraph 18. (4) Mechanized vehicles. For conduct of crews and fire against mechanized vehicles, see paragraph 18. ! 3. CAPABILITIES AND LIMITATIONS OF THE 81-MM MOR- TAR.—The 81-mm mortar is a crew-served weapon. Each mortar is capable of firing an effective concentration in an area 100 by 100 yards. The use of the mortar for firing concentrations is limited by the supply of ammunition. (See FM 23-90.) a. Mobility.—The 81-mm mortar has approximately the same mobility as the heavy machine gun. Its ammunition supply is more difficult, both because of the weight of the projectile and because of the rapidity with which the initial supply may be exhausted. b. Ranges.—The effective range is limited by observa- tion rather than by the maximum range of the weapon. The range of the light shell is from 100 to 3,300 yards; the range of the heavy shell is from 300 to 2,650 yards. Effec- tive observation, however, will rarely be obtained beyond 2,000 yards. Mortar fires should not be placed less than 200 yards from friendly troops. c. Vulnerability.—Due to its high-angle trajectory and effective range, a wide choice may be exercised in the se- lection of firing positions, provided observation is avail- able. Advantage should be taken of deep defilade, or of woods which afford openings through which the mortar can fire. Firing positions should be selected which protect the crew from the fires of rifles and machine guns, and reduce the vulnerability of the mortar and crew to hostile artillery fires and air attack.