This post hospital was organized, as part of the Fort Hospitals of the Defenses of Washington by Brigadier General James S. Wadsworth.

Fort Mansfield was part of the 2nd brigade in the Defenses of Washington north of the Potomac until the forts of this brigade were reorganized as the 1st Brigade in July 1864. Fort Saratoga was the headquarters for the 1st/2nd Brigade, and also had a post hospital. The Washington Indexes indicate that records for this post hospital are listed in the Maryland Indexes.