American Expeditionary Forces on the Western Front (World War I) order of battle

The American Expeditionary Forces (AEF), commanded by General John J. Pershing, deployed to the Western Front during World War I. Its order of battle evolved significantly throughout its time in Europe, as new divisions arrived, units were transferred, and the AEF’s organization matured. What follows is a general overview of the AEF's structure during the major offensives of 1918, not a static, fixed depiction.

Core Organization:

The AEF was structured around corps, which were comprised of divisions. Divisions were the primary combat units, consisting of infantry regiments, artillery brigades, and support elements.

• General Headquarters (GHQ): Located in France, GHQ controlled all aspects of the AEF's operations, including logistics, training, and combat deployment. Pershing, as Commander-in-Chief, reported directly to the U.S. War Department.

• Corps: As the AEF grew, corps were established to manage the increasing number of divisions. Prominent corps included:

  • I Corps: Involved in operations such as the Battle of Cantigny and the Second Battle of the Marne.
  • II Corps: Served alongside British forces for a period, contributing to the breaking of the Hindenburg Line.
  • III Corps: Participated in the St. Mihiel offensive.
  • IV Corps: Engaged in actions during the Meuse-Argonne Offensive.
  • V Corps: Played a major role in the Meuse-Argonne Offensive, one of the largest and most costly battles for the AEF.

• Divisions: The AEF deployed numerous divisions, each with a unique numerical designation. Key divisions include:

  • 1st Division: Known as the "Big Red One," it was among the first American divisions to arrive in France and saw extensive combat.
  • 2nd Division: Composed of a Marine brigade and an Army infantry brigade, known for its fighting prowess.
  • 3rd Division: Earned distinction for its defense during the Second Battle of the Marne.
  • 4th Division: Saw significant action in the Meuse-Argonne Offensive.
  • 26th Division: A National Guard division, engaged in several battles.
  • 28th Division: Also a National Guard division, known as the "Keystone Division," which participated in heavy fighting.
  • 32nd Division: Another National Guard division, nicknamed the "Red Arrow" division, known for breaking through German lines.
  • 42nd Division: A National Guard division formed from units across the country, known as the "Rainbow Division."
  • 77th Division: Composed largely of men from New York City, known as the "Statue of Liberty" Division.
  • 79th Division: Known as the "Cross of Lorraine" Division, it saw significant action during the Meuse-Argonne offensive.
  • 82nd Division: Known as the "All-American" Division, formed from soldiers from all 48 states.
  • 91st Division: A depot division utilized largely for replacement troops.

Composition of a Typical American Division (Approximate):

• Two Infantry Brigades (each with two Infantry Regiments)
• One Artillery Brigade (with artillery regiments)
• Machine Gun Battalions
• Engineer Regiment
• Signal Battalion
• Medical Units
• Supply and Transportation Units

Artillery and Other Support:

The AEF relied heavily on French and British artillery and air support, particularly in the early stages of the war. As the war progressed, the AEF developed its own artillery capabilities. Support units included:

• Artillery Regiments and Brigades
• Air Service (aviation units)
• Tank Battalions (though tanks were often supplied and operated by the French or British)
• Medical Corps
• Quartermaster Corps (responsible for supply and logistics)
• Engineer Units

Command Structure:

The AEF's command structure was hierarchical, with Pershing at the top, followed by corps commanders, division commanders, and regimental commanders.

Evolution of the Order of Battle:

The AEF's order of battle was not static. New divisions arrived throughout the war, and divisions were rotated in and out of combat zones for training and rest. The organization also evolved as the AEF gained experience and adapted to the conditions of trench warfare. The AEF also had significant challenges with integrating African American soldiers into combat units, often assigning them to support roles or loaning them to the French Army.

Note: This overview provides a general picture of the AEF's order of battle. Specific unit assignments and deployments varied depending on the time period and the specific operations in progress. Detailed orders of battle for specific battles and periods can be found in historical records and military archives.