The headquarters was concurrently initiated at San Francisco, with Reserve personnel previously assigned to the demobilized XIX Corps (RAI).

The XIX Corps was not activated prior to World War II and was located in San Francisco as of 7 December 1941 in an inactive reserve status.

The Headquarters, III Armored Corps was constituted in the Army of the United States on 7 July 1942, and activated at Camp Polk, Louisiana on 20 August 1942 under the command of Major General Willis D. Crittenberger during World War II.

[2][3] It fought as part of the First and Ninth Armies, fighting on the Western Front of World War II.

It was allotted to the Regular Army in October 1959 and activated on 1 November that year at Fort Chaffee, Arkansas.