US Army Divisions in World War II
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US Army Divisions in World War II

This site details all U.S. Army divisions that served in World War II from 1939 to 1945. Every infantry, armored, airborne, mountain, and cavalry division is represented.

1st Infantry Division 2nd Infantry Division 3rd Infantry Division 4th Infantry Division 5th Infantry Division 6th Infantry Division 7th Infantry Division 8th Infantry Division 9th Infantry Division 10 Mtn Mountain Division Americal Infantry Division 24th Infantry Division 25th Infantry Division 26th Infantry Division 27th Infantry Division 28th Infantry Division 29th Infantry Division 30th Infantry Division 31st Infantry Division 32nd Infantry Division 33rd Infantry Division 34th Infantry Division 35th Infantry Division 36th Infantry Division 37th Infantry Division 38th Infantry Division 40th Infantry Division 41st Infantry Division 42nd Infantry Division 43rd Infantry Division 44th Infantry Division 45th Infantry Division 63rd Infantry Division 65th Infantry Division 66th Infantry Division 69th Infantry Division 70th Infantry Division 71th Infantry Division 75th Infantry Division 76th Infantry Division 77th Infantry Division 78th Infantry Division 79th Infantry Division 80th Infantry Division 81st Infantry Division 83rd Infantry Division 84th Infantry Division 85th Infantry Division 86th Infantry Division 87th Infantry Division 88th Infantry Division 89th Infantry Division 90th Infantry Division 91st Infantry Division 92nd Infantry Division 93rd Infantry Division 94th Infantry Division 95th Infantry Division 96th Infantry Division 97th Infantry Division 98th Infantry Division 99th Infantry Division 100th Infantry Division 102nd Infantry Division 103rd Infantry Division 104th Infantry Division 106th Infantry Division Philippines Infantry Division 1st Armored Division 2nd Armored Division 3rd Armored Division 4th Armored Division 5th Armored Division 6th Armored Division 7th Armored Division 8th Armored Division 9th Armored Division 10th Armored Division 11th Armored Division 12th Armored Division 13th Armored Division 14th Armored Division 16th Armored Division 20th Armored Division 11th Airborne Division 13th Airborne Division 17th Airborne Division 82nd Airborne Division 101st Airborne Division 1st Cavalry Division 2nd Cavalry Division

The U.S. Army
During World War II about 16,000,000 personnel served in the U.S. Military. Approximately 11,200,000 or 70% served in the U.S. Army (4,200,000 served in the Navy and 660,000 in the Marines.)

The U.S. Army was re-organized into three forces in March 1942:

  • Army Ground Forces (AGF). According to the The Army Almanac, "Its mission was to provide ground force units properly organized, trained and equipped for combat operations." About 4,400,000 personnel were part of the Army Ground Forces during the war. They sustained about 80% of the U.S. Army casualties.
  • Army Service Forces (ASF). The ASF, originally called Services of Supply, was responsible suppling and servicing the U.S. Army. Organizations under ASF included: corps of engineers, quartermaster corps, medical corps, signal corps, chemical warfare service, ordnance department, and the military police.
  • Army Air Forces (AAF). The AAF was responible for the training and making ready the air component of the U.S. Army. The Army Air Forces became an independent service (U.S. Air Force) in 1947.

At it's peak in March 1945, the U.S. Army had 8,200,000 personnel. A comparison of Army Ground Forces strength with total U.S. Army strength is provided below.

DateStrength U.S. ArmyStrength Army Ground ForcesPercent of U.S. Army
31 Dec 19411,657,157867,46252.4%
31 Dec 19425,398,8881,937,91735.9%
31 Dec 19437,582,4342,551,00733.6%
31 Mar 19458,157,3862,753,51733.8%
Source: Greenfield, Palmer, & Wiley. US Army in World War II, The Organization of Ground Combat Troops

The Army Ground Forces
Personnel in the Army Gound Forces were grouped into two areas: divisional forces and non-divisional forces. In March 1945, there was about 1,200,000 personnel assigned to divisions and 1,500,000 to non-divisional units.

The core combat arm of the Army Ground Forces was orginized around the division formation. The division was created to be the smallest Army organization capable of performing independent operations. Ninety-one divisions were formed by the U.S. Army in World War II. In general, a division contained about 15,000 troops. See below for a complete breakdown of a division.

Non-divisional forces included service units and some additional combat troops not initially assigned to a division.

Note: most service units were allocated across all U.S. Army organizations. For example, both the Army Service Forces and Army Ground Forces had engineer units. In addition, engineer units were part of divisions while other engineer units were part of non-divisional personnel.

Combat troops of the U.S. Army are classified by the weapons and methods used in combat.

Divisional facts:

  • There were 5 types of divisions: infantry, mountain, armored, airborne, and cavalry.
  • 91 divisions were mobilized during the war: 68 infantry divisions, 1 mountain division, 16 armored divisions, 5 airborne divisions, and 2 cavalry divisions.
  • All divisions were activated in the United States except for the following divisions: Philippine (activated in the Philippines), Hawaiian (activated in Hawaii and renamed the 24th division), 25th (activated in Hawaii from troops of the Hawaiian division), and Americal (activated in New Caledonia.)
  • There were three major theaters of operation during the war: Pacific (22 divisions were deployed to the Pacific), Mediterranean (15 divisions), and Europe (61 divisions). Seven divisions served in both the Mediterranean and European Theaters (1st, 3rd, 9th, 36th, 45th infantry divisions; 82nd airborne; and 2nd armored.)
  • Two divisions were disbanded or deactivated before the end of the war: the Philippine division was destroyed and disbanded on 10 April 1942; and the 2nd Cavalary division was activated and inactivated twice: 15 Apr 41 to 15 Jul 42 and 23 Feb 43 to 10 May 44.
  • Three divisions did not enter combat: 98th Infantry division, 13th Airborne division, and the 2nd Cavalary division.
  • By June 1946, 74 divisions were inactivated or disbanded leaving 17 divisions on active duty.

Division Components
All divisions of the U.S. Army originated from the following four sources:

The numbering of divisions followed a pattern established in 1917 during World War I. The numbers 1 to 25 were reserved for the Regular Army; numbers 26 to 45 for the National Guard; and numbers 46 to 106 for the Army of the U.S. However, there were a number of exceptions. The two airborne divisions, 82nd and 101st, were redesignated Regular Army when they converted from infantry to airborne divisions. The 25th was formed from troops of the Hawaiin division and was classified as an Army of the U.S. division. The 42nd division was a National Guard division in World War II but was mobilized as an Army of the U.S. division.

Division Life Cycle
In general, a division went through the following phases during its existence:

  • Cadre selection: A cadre of officers and men (about 1300 men or 10% of the division) were selected from a current division to serve as the nucleus of the new division.
  • Division commander selection: The commanding general of the division was selected by General George Marshal, chief of staff of the United States Army.
  • Cadre training: The cadre trained for a few months prior to activation.
  • Officer fill out: Officer schools and replacement centers sent personnel to fill the complement of officers.
  • Activation: The division was formally activated, that is, put in to existence so that it can be filled out.
  • Division expansion: Draftees and enlistees were integrated into the division bringing it up to its authorized strength.
  • Training: The division trained for a year.
        17 weeks of basic and advanced training
        13 weeks of unit training
        14 weeks of combined arms training and large-scale exercises
        8 weeks of final training
  • More training: The division participated in large scale, multi-division training exercises.
  • Overseas movement: The division was moved to a port, loaded on transports and embarked to an overseas theater.
  • Additional training: If possible the division trained for a few more weeks.
  • Combat: The division moved to the front lines and entered combat.
  • Relieved: Periodically the division was relieved from combat for rest, recuperation, re-equipping and retraining. After a break of a few days to a few months, the division re-entered the front lines.
  • Inactivation or remained on duty: Personnel were returned to the United States and released from the Army and the division was de-mobilized. Most of the regular army divisions remained on duty in Europe or the Far East.

The ten divisions with the most battle casualties are presented below. Casualties are defined as killed in action, wounded in action, captured and interned, and missing in action.

The five divisions with the most battle casualties in the Pacific Theater are provided below. Casualties are defined as killed in action, wounded in action, captured and interned, and missing in action.

Days of Combat
The ten divisions with the most days of combat are listed below.

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