bigpigeon.us webpage WWII US > WWII Ground Forces, © 2023 by Robert A. Christiansen, updated by RAC 11 Jan 2023.​
The usual organizational structure of US 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: ​See also: Useful Order of Battle links: ​
Notes:
  • Regimental-sized and larger combat units included smaller units from many Arms and Service branches, the major Arms branches being Infantry, Artillery, Armor, 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 consisted of 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. Their horses were sent to Burma before they first saw combat.
  • 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. Generally their main weapon was large mortars used for smoke generation to mask ground operations.
  • The many tank destroyer battalions deployed were more-often not used in massed defense against enemy tank attacks but rather to support infantry.
  • Antiaircraft artillery remained as 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 antitank battalions were assigned 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 > WWII Ground Forces webpage: