On September 2, 1862, the U.S. War Department issued General Orders, No. 122, announcing that Major General George B. McClellan was given command of all troops for the defense of the capital.
General Orders, No. 122.
War Dep’t, Adjutant General’s Office
Washington, September 2, 1862
Major General McClellan will have command of the fortifications of Washington, and of all troops for the defense of the capital.
By Command of Major General Halleck:
E.D. TOWNSEND, Assistant Adjutant General.