Constituted 24 June 1921 in the Organized Reserves as the 325th Engineers, an element of the 100th Division. Organized in December 1921 with Headquarters at Huntington, West Virginia (Location of Headquarters changed 27 October 1931 to Charleston, West Virginia.) Redesignated (less 2d Battalion) 23 February 1942 as the 325th Engineer Battalion. Ordered into active military service 15 November 1942 and reorganized at Fort Jackson, South Carolina, as the 325th Engineer Combat Battalion. Inactivated 14 January 1946 at Camp Kilmer, New Jersey.
Headquarters Detachment entitled to Meritorious Unit Commendation (Army). Streamer embroidered European Theater (Headquarters and Service Company, 325th Engineer Combat Battalion, cited: GO 75, 100th Infantry Division, 1945)