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bigpigeon.us webpage WWII US > Ground Forces, © 2025 by Robert A. Christiansen, updated by RAC 20 Feb 2025​
The usual organizational structure of US Army WWII ground forces, from largest to smallest units, was
         Army Group > Army > Corps > Division > Regiment > Battalion > Company > Platoon > Squad.
Links to Big Pigeon's WWII: US > WWII Ground Forces subpages: Related webpages: Useful Order of Battle links: ​
WWII US Ground Forces Notes:
  • Regimental-sized and larger combat units included smaller units from several Arms and Service branches, the major Arms branches being Infantry, Artillery, Armor, Cavalry, and (sometimes at least) Engineers.
  • Some organizational schemes had a section structure intermediate between a platoon and a squad.
Various ad-hoc combat organizations smaller than a division but generally larger that a battalion included:
  • Infantry Regimental Combat Teams were built around an infantry regiment and supporting units. The best-known was the Japanese-American 442nd Regimental Combat Team, which fought in Italy and France.
  • Armored Combat Commands usually included a tank battalion, an infantry battalion, and an artillery battalion. They were heavily used both in the Mediterranean and European Theaters. Within an armored division, they would be identified as CCA, CCB, and CCR.
Many company, battalion, or regimental combat units were independent in that they were not permanently assigned to a division, but were managed at the corps or army level.
  • An example was the 112th Cavalry Regiment of the Texas National Guard which served in the Southwest Pacific. My daughter's father-in-law, Lloyd Joyce, served in this unit. They served as infantry; their horses were sent to Burma before they first saw combat on New Britain.
  • As the need arose, an army or corps commander would assign independent tank, tank destroyer, artillery, antiaircraft artillery, chemical, or engineer units to a division. These units, most often of battalion size, often served with a division for extended periods.
  • Although chemical warfare was not used in WWII, numerous chemical battalions served. They used large mortars for smoke generation to mask ground operations.
  • The many tank destroyer battalions deployed were seldom used in massed defense against enemy tank attacks but were often used to support infantry.
  • Antiaircraft artillery was part of the Coast Artillery Corps through WWII. As the threat of enemy air attacks decreased late in the war, antiaircraft artillery battalions began to be disbanded with the personnel assigned to front-line combat units.
  • A WWII infantry division did not include armored vehicles; tank and tank destroyer battalions were assigned to a division as deemed necessary.
Using the above links, you may be able to do some web research. Two examples follow.
Example 1 - Suppose you know your grandfather served in an infantry division in the ETO and you know his unit (e.g., 571st Signal Co.), but you don't know his division: Example 2 - Suppose you know your grandfather served in the ETO, you know his unit (e.g., 70th Tank Bn.), and you've heard that he might have been in the 4th Infantry Division.
  • Enter https://history.army.mil/documents/ETO-OB/ETOOB-TOC.htm
  • You should see the table of contents for the ETO Order of Battle volume.
  • Click on the hotspot for the 4th Infantry Division chapter.
  • You should see the 4th Infantry Division chapter text.
  • Scan through the text until you see the Attachments section, and within it the Armored subsection.
  • Sure enough, the 70th Tank Bn. was generally attached to the 4th Infantry Division.
Sources for Big Pigeon's WWII US > Ground Forces webpage: