How the Modern U.S. Army Was Born to Fight World War II
January 16, 2021 Topic: History Region: Americas Blog Brand: The Reboot Tags: World War IIUnited StatesU.S. ArmyNazi GermanyOrganization

How the Modern U.S. Army Was Born to Fight World War II

It took a lot of reorganization, but the efforts paid off.

Key point: Good organization and logistics helped America build a mighty fighting machine. Hitler did not stand a chance.

The definitive combat unit of comparable strength among the forces of the world during the 20th century was the division. Not all divisions, however, have been of the same size. The number of men in Allied and Axis divisions during World War II varied considerably. The number of men in an American division also varied depending on the type of division, for example, infantry, airborne, light, mechanized, armored, or Marine Corps. Manning of American divisions even varied as the war progressed, and reorganizations were made to ensure the most efficient use of manpower and to reflect the tactical deployment in the various theaters of the world. Although a standard division might be desirable, it was not always viable. Tanks, for instance, were suited to the plains of Europe but of less use in the steaming jungles of New Guinea.

This first appeared earlier and is being reposted due to reader interest.

A division has been defined as “a major administrative and tactical unit/formation which combines in itself the necessary arms and services for sustained combat, larger than a brigade/regiment and smaller than a corps.” Inherent in such a definition is that a division is a combat unit that contains maneuver elements, infantry, or armor; fire support elements, mainly artillery but also tank or antitank units; and logistical or service support elements. The last includes motor transport, engineer, maintenance, supply, medical, and communications units. These three legs— maneuver, fire support, and logistics—enable a division to conduct sustained combat operations.

The Development of the Modern Army Division

Although the Civil War armies and the army sent to Cuba, Puerto Rico, and the Philippines in 1898 had units called divisions, they were mainly infantry or cavalry and lacked the other organic elements that constitute a modern division. The first real divisions of America’s armed forces were those sent to France in 1917-1918. They numbered more than 28,000 men and were more than twice the size of those of the other Allies or Central Powers. American Expeditionary Forces (AEF) divisions consisted of two infantry brigades of two regiments each; three artillery regiments, two of medium and one of heavier artillery; an engineer regiment; plus the various housekeeping units of supply, transport (some truck but mostly horse-drawn), medical, sanitation, supply, and signal. The rifle companies, of which there were four in a battalion, were more than 250 strong. There were three squads of eight men in each platoon, but the companies had seven platoons apiece. The infantry regiments had three battalions. Due to their composition of four regiments of two brigades, this organization was known as the “square division.”

The square division was the standard Army formation for most of the period between the world wars. Although mostly paper formations and vastly undermanned, the Regular Army (RA), National Guard (NG) and Organized Reserve (OR) divisions were square divisions. The difference between the NG and OR divisions was that the former were multistate units whose regiments were under the governors of their respective states until called to federal service while the latter were cadres of Reserve officers and noncommissioned officers for mobilization. This was consistent with the reforms made by Secretary of War Elihu Root after the difficulties of the Spanish-American War, which then provided for an orderly, expandable Army.

From Squares to Triangles

In the mid-1930s, there was a public reawakening concerning the armed forces. The administration of President Franklin D. Roosevelt, as a measure to get the Depression-stalled economy going again, decided that deficit spending to fund public works would be a prudent move. Included in such public works were warships for the Navy. The Army also benefited in that installations throughout the country were improved and even some air bases were constructed for the Army Air Corps.

The thinkers in the Army had never been idle, and they welcomed the opportunity to “get their nose under the tent” and share in the renewed interest in the armed forces. Although the Army was still saddled with the weaponry of World War I, a decade and a half had brought technical improvement. The biggest was in motor transport. Infantry could be given greater mobility moving to the battlefield, and units could be supplied more quickly. The reduction in time for movement could be translated into a reduction of manpower to provide the cutting edge. Firepower had been improved to include semiautomatic rifles, mortars, artillery, tanks, and aircraft.

A word about tanks is appropriate. Tanks had been an Allied innovation in World War I to break the stalemate of trench warfare. The AEF had formed a Tank Corps. It was disbanded after the war and what were formerly “tanks” were transferred to the infantry as “combat cars.” Since tanks had a connotation of offense, the euphemism was a way of appeasing a public, which would support an armed force for defense but abhorred any hint of its use offensively.

Army thinkers began to reappraise the tactics of the battlefield and the type of units that would have to fight. In the world war, infantry regiments attacked in a column of battalions in linear waves. Battalions of a regiment would move successively across no man’s land to take the enemy trenches after artillery had neutralized the defenders. The two lead battalions suffered relatively high casualties, but the breakthrough could be exploited by the third, or reserve battalion. A concept of “two up and one back” emerged. It was just a short step to applying this concept at all levels within a division. Thus was born the “triangular division.”

The Factor of Three

The factor of three was applied at all levels in the new, albeit experimental, division. Three squads made up a platoon. Three platoons were a rifle company. Three rifle companies with a weapons and headquarters company made up an infantry battalion. Three infantry battalions with a headquarters and service company were an infantry regiment. The division had three infantry regiments. Field artillery in the division consisted of three light battalions of three four-gun batteries and a medium battalion of four-gun batteries. In the initial artillery regiment of the first triangular division, circa 1936, the light battalions had 75mm howitzers and the medium battalion had 105mm howitzers. By the time war came, the light howitzers were 105mm and the mediums were 155mm.

These were two of the three legs of the triangular division. The third leg was rounded out by a reconnaissance troop, an engineer battalion, a medical battalion, and companies of ordnance, quartermaster, signal, and division headquarters personnel. There was also a military police platoon and a division band. Medical detachments were with the infantry and artillery to provide forward support on the battlefield.

The 1936 triangular division had 13,552 officers and men, of which 7,416 were in the three infantry regiments. After an initial field test, the recommended division in 1938 was reduced to 10,275, of which 6,987 were infantry. In June 1941, the division had risen in strength to 15,245, with 10,020 infantrymen. Fourteen months later, in August 1942, the division had increased to 15,514, but the infantry had been reduced to 9,999. A further reduction was proposed in early 1943, to 13,412 with 8,919 infantrymen.

The organization that fought the war (beginning in August 1943) was one of 14,255 officers and men, with 9,354 in the infantry. During the last year of the war, the standard infantry division had a strength of 14,037, with 9,204 in the infantry regiments. During all the reorganizations and changes, a triangular division was about half the size of the square division it replaced.

In addition to increased mobility there were other reasons for the fine-tuning of the infantry division during the war. The primary one, of course, was combat experience. Weaknesses were determined and remedied. Strengths were evaluated and reinforced. There were mundane reasons as well for tinkering with the size of an infantry division. Reducing the size from 15,514 (August 1942 level) to 14,255 (July 1943 level) meant a savings of 1,259 men. Thus for every 11 divisions, the savings in manpower would generate a 12th. Another reason was the wartime shortage of shipping. Slightly smaller divisions took up fewer “boat spaces.” This was important since the Army had to cross the oceans to fight the enemies. When the forces for D-Day and beyond were being built up in the United Kingdom, the two largest transoceanic liners, Britain’s Queen Mary and Queen Elizabeth, could “comfortably” carry a U.S. infantry division every other week. This was no minor factor. Another reason to keep the infantry division to the smallest size consistent with projecting its combat power offensively was the finite manpower pool in the United States.

A Draft for the “Arsenal of Democracy”

While the number of American men of combat age who were physically fit for induction was between 20 and 25 million, there was competition for the pool other than the Army’s infantry. Service troops, such as engineers, supply men, and others were needed to make frontline infantry effective. The Army Air Corps, by then the Army Air Forces, had a large claim on manpower. The Navy and Marine Corps needed men. And, in addition to its fighting forces in the field, the United States was both the “arsenal of democracy” and the breadbasket of the Allies. Although many women labored in the factories and the fields, a large body of men was needed to turn out the weapons for the United States and its Allies.