THE UNITED STATES ARMY IN WORLD WAR II
by Rich Anderson

Organization of the Army Ground Forces

The Army Ground Forces (AGF) was created in a major reorganization of the Army General Headquarters on 9 March 1942. AGF became responsible for the organization, training, and equipping of all Army units other than the Air Corps. The first commander of AGF was Major General (later lieutenant general) J. Lesley McNair (General McNair was accidentally killed by U.S. bombs while observing Operation COBRA on 25 July 1944). General McNair was the final arbiter on Army organization. He campaigned tirelessly to reduce overhead in U.S. divisions, insisting on as much streamlining as possible. There were two reasons for this. First, shipping space was at a premium for not only combat but also support units, and all supply items had to be shipped from the United States over great distances to foreign ports. Second, NcNair and other planners realized that the U.S. manpower pool was not inexhaustible. Industry and farming in the United States, and the massive expansion of the Navy, Marine Corps, Coast Guard, Army Air Corps, and Merchant Marine all absorbed vast numbers of men. The 213-division Army envisaged by the Victory Program of 25 September 1941 was never even close to being achieved; it proved to be difficult enough to man the 89 divisions eventually fielded.

Pooling

An adjunct to General McNair's efforts to streamline the army was his effort to pool all non-divisional combat assets into homogeneous battalion-size units. Pooled units were to be held by corps or armies and were to be attached to divisions as needed. Field artillery, engineers, tanks, tank destroyers, antiaircraft artillery, and infantry units were all part of the pool. To facilitate pooling, in February 1943 all of the existing field artillery, antiaircraft artillery, and engineer combat regiments were broken up into separate battalions. The regimental headquarters were then utilized to form group headquarters. The group headquarters was intended to provide command and control for manageable aggregations of the large number of pool units.

A Note on Terminology

The convention utilized by the U.S. Army is that the designation of an army is spelt out (First), corps use Roman numerals (XX), divisions, brigades, regiments, battalions, and platoons all use Arabic numerals (90th), and companies, troops and batteries are lettered.

Corps, Army, and Army Groups

Twenty-four corps were activated by the end of the war, all except the XXXVI Corps served overseas. Three were originally formed as armored corps, of which the I Armored Corps was inactivated in Morocco and its personnel utilized in the formation of the Seventh Army, the II Armored Corps became the XVIII Airborne Corps, and the III Armored Corps became the XIX Corps. The other corps organized were the I-XVI, XX-XXIV, and XXXVI.

Twelve army headquarters eventually existed. By 1945, the First, Third, Seventh, Ninth, Fifteenth, and First (Allied) Airborne Armies were operational in the ETO, the Fifth was in the MTO, the Sixth, Eighth, and Tenth were in the PTO, and the Second and Fourth Armies were in the United States with training missions.

Finally, four army group headquarters were formed. The 6th and 12th Army Groups served in the ETO and the 15th Army Group in the MTO.

With few exceptions, all the armies and corps were organized by the AGF or existed in the Regular Army or Organized Reserves at the start of the war. However, the Fifth, Sixth, and Seventh Armies, First (Allied) Airborne Army, and all of the army groups were activated overseas.