It is also home to the Fort Harrison VA Medical Center and Montana State Veterans Cemetery, located adjacent to the military installation.

Fort William Henry Harrison (1895–1913) was authorized by a Congressional act of 12 May 1892 which was intended to establish, as a part of a greater consolidation program, concentrations of troops in a few larger installations so that smaller installations could be abandoned.

[2] Fort William Henry Harrison's most famous contribution during the 20th century was its 1942 use as the organization and training area for the U. S. Army's 1st Special Service Force,[3] a joint World War II American-Canadian light infantry brigade[4] made famous by the 1966 book, The Devil's Brigade, co-written by Robert H. Adleman and George Walton, and The Devil's Brigade, the 1968 American war film.

The post is now home of the Montana National Guard's Joint Forces Headquarters, 95th Troop Command, 208th Regional Training Institute, Training Center Headquarters, 190th Chemical Reconnaissance Detachment, Montana Medical Readiness Detachment, 83rd Civil Support Team, 1049th Fire Fighting Detachment, and I Company 145th Forward Support Element.

Additionally, there is as an Army Reserve training facility and Veterans Administration Hospital.