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

Fort Baker Post Hospital served the 3rd brigade in Haskin's Division (22nd Army Corps) and remained the hospital when the brigade was part of Hardin's Division.

The 3rd Brigade consisted of these forts, garrisons and redoubts: Davis (Head Quarters), Baker, Wagner, Ricketts, Stanton, Snyder, Carroll, Greble, Mahan, Chaplin, Meigs, Dupont, Foote.

In 1862, a brick church building was used until the hospital moved to a location on the heights overlooking Anacostia (Uniontown) between Forts Davis and Wagner. The Indexes record that the "Hospl. moved to Ft. Davis in April '63; - Sept. 63 changed to ground south of Ft. Wagner; - moved back to former location Oct. 64 and then continued to close."