♦ The Infantry Division 1941-45 ♦

The United States Army in World War II


Paris, 29 August 1944: The 28th Infantry Division—the Keystone Division—marches down the Champs Élysée four days after the liberation of the city
(Photo: US Army Center of Military History)

● ● ●

The history of the modern US Army infantry division begins with the National Defense Act of 1916, which provided for an increase in the size of the Regular Army and the establishment of a permanent divisional organization. Up to then the largest permanent organization had been the regiment, and the last time that divisions had existed in large numbers was during the Civil War.

The organization adopted for the Army division in 1916, which would also apply to the National Guard, was “triangular”: three infantry brigades, each with three infantry regiments, plus artillery and other support units. (At that time an infantry regiment had the actual strength of a battalion.) But not much was done to implement this scheme and by the time that the United States entered World War I in the spring of 1917 it was considered obsolete. Instead, the Army adopted a much larger “square” organizational template: two infantry brigades, each with two infantry regiments, each regiment with three battalions. The square division also had a field artillery brigade with three regiments (six battalions), an engineer regiment, and a machine gun battalion. With various modifications, this square configuration remained standard for the Army’s infantry divisions up to 1939.

In combat the square division had demonstrated considerable staying power—due to its size—but it lacked mobility and proved difficult to support. After the war considerable thought was given to the development of a new, smaller, more mobile infantry division, with motor vehicles replacing horses. The ultimate result was a new triangular organization. The infantry brigades and one of the infantry regiments were eliminated, the division artillery was reduced to four battalions, and support units were reduced in proportion. The overall reduction in manpower was from 22,000 to about 12,500.

The new organization was approved in 1939 and by late 1941 all infantry divisions of the Regular Army were triangular. The divisions of the National Guard, however, retained their square configuration. The reason for this was partly political. Converting the NG divisions from square to triangular would deprive many officers of their commands—a prospect most unwelcome in both the states and the National Guard Bureau. Only a year to eighteen months after their induction into federal service (1940-41) were they finally converted.

The officer most influential in the design of the wartime triangular infantry division was Lieutenant General Leslie J. McNair, who was Chief of Staff, General Headquarters (GHQ) US Army from 1940 to 1942 and then Commanding General, Army Ground Forces (AGF) when that organization replaced GHQ. He served in the latter capacity until he was killed in France on 25 July 1944. McNair had been involved in issues of Army reorganization since the mid-1930s, when he championed the concept of a lighter, more nimble infantry division. As commander of AGF, he held primary responsibility for the organization, mobilization and training of all Army ground combat forces: an undertaking of vast complexity, embracing a myriad of factors.

Lieutenant General Leslie J. McNair as Commander, Army Ground Forces in 1942
(Photo: US Army Signal Corps)

One great challenge that McNair faced was the integration of new weapons into the infantry division. This affected the organization of the infantry at every level, from the rifle squad to the regiment. In 1935 the primary infantry weapons were the bolt-action Springfield rifle; the Browning Automatic Rifle (BAR); the tripod-mounted, water-cooled 30-caliber Browning machine gun; and the 81mm Stokes mortar of World War I vintage. In 1938-40, however, new weapons began to be introduced: the M1 self-loading rifle, a greatly improved BAR, the Thompson submachine gun, a lighter air-cooled version of the Browning machine gun, the .50-caliber heavy machine gun, the light 60mm mortar, the 37mm antitank gun. All these new weapons greatly increased the infantry division’s firepower, despite the reduction in manpower.

The triangular infantry division underwent various alterations between 1941 and 1944, but none of these changes affected its basic organization. The divisional antitank battalions that existed in two or three divisions in 1941 were removed and allocated to the new Tank Destroyer command when it was established late in that year. In mid-1942 the quartermaster battalion (supply, transport and maintenance) was dissolved and replaced by separate quartermaster and maintenance companies. The infantry regiments acquired a cannon company with six light 105mm howitzers. New and improved weapons were introduced, such as the M8 armored car (37mm gun) in place of the machine gun-armed M3 armored scout car, and the 2.36-inch antitank rocket launcher (bazooka). The ultimate configuration of the triangular infantry division (1944-45) is shown in the accompanying diagram.

Distinguishing Flag of the 1st Infantry Division: "The Big Red One"

Though many of its sub-units such as the division artillery and the cavalry reconnaissance troop were fully motorized, the infantry division as a whole was not. Though American industry was more than capable of providing the necessary motor vehicles, Army planners judged that full motorization of infantry divisions would place excessive demand on the shipping needed to deploy them to Europe and the Pacific. (The same considerations led to a reduction in planned armored divisions from the fifty or sixty envisioned in 1941-42 to the sixteen ultimately activated.) Instead, quartermaster truck companies would be attached to infantry divisions as necessary. One such company, with its 48 x 2.5-ton trucks and 1-ton trailers, was capable of fully motorizing an infantry regiment.

Nor did the infantry division include anything in the way of armored fire support vehicles. In the 1920s the Army distinguished between infantry tanks (providing such support) and “combat cars” (light tanks in the cavalry branch) but the evolution of mobile/mechanized combined arms doctrine did away with this distinction. In 1940 the Infantry branch lost all control over tank development. While it was recognized that tank support was vital to the infantry, this would be provided by independent tank (later armored) groups of two or three tank battalions. Such groups proved excessively large, however, and during World War II it became common practice, particularly in the European theater, to attach a separate medium tank battalion to each infantry division on a more or less permanent basis. Typically, the battalion’s three medium tank companies were parceled out to the division’s infantry regiments. The light tank company could be attached to the division’s mechanized reconnaissance troop or, with other battalion elements, held under control of the division HQ as a mobile reserve.

Infantry rifle squad and M4 Sherman medium tank
(Photo: US Army Center of Military History)

The attached tank battalion was sometimes augmented or replaced by a self-propelled (SP) tank destroyer battalion. The SP tank destroyer resembled a medium tank but it was faster, had lighter armor and an open-topped turret, and mounted a more powerful main gun. Prewar doctrine had envisioned TD battalions operating in groups of three or four against enemy armored forces. But large-scale armored clashes on the Russian Front model were rare in the European and Pacific theaters and the TD battalions were mostly attached to armored and infantry divisions.

In the infantry division both tanks and SP tank destroyers were employed as assault guns. Individual tanks operating with infantry platoons proved extremely useful in the 1944-45 Siegfried Line battles, knocking out enemy bunkers and providing direct fire support for advancing infantry. The more lightly armored tank destroyers were not quite so successful in this role, though their high-velocity main guns were highly effective bunker busters.

No doubt the most prominent strong point of the triangular infantry division was the division artillery. This consisted of four battalions: three with a total of 36 x 105mm howitzers and one with 12 x 155mm howitzers. Not only were the weapons themselves of excellent design and performance, but their tactical employment was devastating effective. Advanced communications and fire direction techniques made it possible to engage targets rapidly and to mass the fires of the entire division artillery on a single target. (The organization and employment of US Army field artillery in World War II will be covered more fully in a forthcoming article.)

But there were challenges as well. The most pressing, which became acute in the European theater during 1944-45, was a shortage of infantry replacements. In early December 1944, for example, Patton’s Third Army was 11,000 infantrymen short: roughly the rifle strength of two infantry divisions. There were two reasons for this: combat casualties in the infantry and the difficulty of replacing them.

Once a division entered combat, the main burden of the fight inevitably fell on the infantry and after a few weeks it was common for a rifle platoon or company to have suffered nearly 100% casualties—meaning that almost all of its original personnel had been killed, wounded, evacuated sick or reported missing. Particularly serious was the loss of trained small-unit leaders—junior officers and NCOs. These losses, bad enough in themselves, proved especially hard to replace. Competing demands for manpower, among the armed forces and among the branches of the Army itself, meant that there were never quite enough men allotted to the infantry. And late in the war, the manpower that was allotted of indifferent quality: 18-year-olds with less than six months’ training, older classes of draftees, often with poor educational qualifications. Thus infantry battalions found themselves manning the line with critical gaps in their ranks, and little time to absorb the often sketchily trained replacements that they received.

The Army had been grappling with this manpower problem since 1942; it was a major factor in General Marshall’s 90-division gamble. In late 1944, emergency measures were adopted. Many antiaircraft artillery units, surplus to requirements after the effective demise of the Luftwaffe, were disbanded and their personnel distributed as infantry replacements. Rear-echelon units were similarly assessed and either disbanded or reduced in strength. But these measure, while helpful, could not solve the manpower problem, which was by then systemic. Fortunately, however, Germany was by then on the brink of defeat, with many of its own divisions reduced to pitiful remnants.

Immediately after the termination of hostilities in Europe, the General Board, European Theater of Operations, United States Army, was set up to conduct a wide-ranging review of the organization, equipment, and tactical employment of the infantry division in light of combat experience. The Board's general conclusion was that the wartime triangular infantry division's major subordinate elements were insufficient to carry out independent combat operations. Particularly remarked upon was the lack of an organically assigned tank battalion. Other recommendations included the addition of an antiaircraft artillery battalion, a strengthening of the division artillery, the expansion of the mechanized cavalry reconnaissance troop into a full squadron, and the augmentation of the division's service and support elements. In the postwar period most of these proposals were adopted, though the basic triangular configuration of the infantry division was retained until it was replaced by the Pantonic organizational scheme in the late 1950s.

● ● ●

Armament of the 1944-45 Infantry Division 

36 x 105mm howitzers

12 x 155mm howitzers

18 x 105mm infantry cannons

27 x 57mm antitank guns

144 x light (60mm) and medium (81mm) mortars

393 x machine guns (cal .30 and cal .50)

557 x anti-tank rocket launchers (bazookas)

90 x submachine guns

5,204 x carbines

6,761 x rifles

Organizational Diagrams 


Copyright © 2020 by Thomas M. Gregg. All Rights Reserved

BACK to WAR ROOM Front Page