The Combatants I: The American Infantry

In this series of articles, I will describe combat organizations of various armies, and attempt to assign them a rating that addresses the weight of fire they could produce in one minute of combat.

To keep the analysis simple, the weight of fire will be the sum of the actual weight of metal and high explosives the fire produced by the weapons of these units. The weapons represented by the analysis will be those likely to be used in combat. Thus, while a U. S. infantry battalions might have many machine-guns dedicated to anti-aircraft defense, only those machine-guns likely to have been used in ground combat will be reckoned.

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A U. S. infantry battalion in the final year of the war was made up of three rifle companies and a heavy weapons company. The battalion included an antitank platoon of three 57-mm antitank guns, but these were rarely used during offensive operations and the men were often used to form an extra ad-hoc rifle platoon. The antitank platoon will not be included in the following calculations, and pistols will also not be included as they are used only at extreme short range and are practically more of a melee weapon than a regular infantry weapon.

So, each of the three rifle companies had three rifle platoons, and each rifle platoon had three squads of 12 men each. Each echelon from platoon on up also had headquarters units of varying size. For the sake of calculation, I'll assume every man in the rifle company is a potential combatant, or part of what can be termed the "bayonet strength". Considered in this fashion, a rifle company consisted of the following armament (10 men had M1911A1 pistols as primary armament):

44 Carbines, M1C
129 Rifles, M1
3 60-mm mortars, M2
1 50-Caliber Heavy Machine-Gun, M2HB
2 30-Caliber Light Machine-Guns, M1919A6
9 30-Caliber Browning Automatic Rifles, M1918A1

So how does one assign a "weight of fire" to these weapons? A good first step for weapons that fire bullets (as opposed to shells that explode), is to consider the sustained rate of fire. Sustained rate of fire is rarely described in books, so I will arbitrarily assume the sustained rate of fire to be 45 per cent of the weapon's cyclic (full-speed) rate of fire. This rate will be calculated in minutes and multiplied by the weight of the bullet. To this will be added the weight of the number of 60-mm mortar projectiles that can be realistically fired in one minute on a sustained basis. The resulting sum can be considered the "weight of fire" that this company could theoretically produce in one minute. Let's assign a sustained rate of fire and bullet weight to the smaller weapons:

M1C Carbine: 44 x 30 rounds/minute x 7.00 grams = 9.24 Kilograms
M1 Rifle: 129 x 30 rounds/minute x 9.85 grams = 38.12 Kilograms
M2 HMG: 1 x 236 rounds/minute x 46.01 grams = 10.86 Kilograms
M1919A6 LMG: 2 x 203 rounds/minute x 9.85 grams = 4 Kilograms
M1918A1 BAR: 9 x 150 rounds/minute x 9.85 grams = 13.30 Kilograms (Note 1)
60-mm Mortar: 3 x 8 rounds/minute x 1360 grams = 32.64 Kilograms

Total: 108.16 Kilograms of metal and high explosive in one minute, or 238 pounds.

For three rifle companies, then, the total would be 324.48 Kilograms or 713.86 pounds.

Repeating the above process for the battalion's heavy weapons company, the following weapons are identified:

6 81-mm mortars, M1
8 30-Caliber Heavy Machine-Guns, M1917A1

The weight of fire calculations for these are:

M1917A1 HMG: 8 x 250 rounds/minute x 9.85 grams = 19.7 Kilograms (Note 2)
81-mm Mortar: 6 x 8 rounds/minute x 3145 grams = 151 Kilograms

The total for the heavy weapons company is 170.7 Kilograms, or 375.54 pounds. Combined with the fire weight of the three rifle companies, the battalion can produce 495.18 Kilograms, or 1,089.4 pounds of metal and high explosive in one minute. While this figure may seem uninteresting at the moment, it will become more interesting when like figures are calculated for the infantry battalions of other armies of the period.

During the campaign in NW Europe, U. S. rifle companies began equipping each platoon with two additional BARs, for a total of 45 BARs in the battalion. This was an obvious response to the superior fire weight of German belt-fed machine-guns. In the Pacific Theater, the Marines recognized the inability of the BAR to generate a sufficient weight of fire and compensated by equipping every Marine rifle squad with three BARs.

Note 1: The BAR was a magazine-fed weapon with 20-round magazines. Magazine reload time accounts for lower rate of fire (cyclic rate of fire for the BAR was 550 rounds/minute).

Note 2: The M1917A1 was a water-cooled weapon and thus capable of longer bursts of sustained fire than its air-cooled cousins, the M1919A4 and M1919A6.