Department of Washington, was a department of the Union Army constituted on April 9, 1861. It consisted of the District of Columbia to its original boundaries, and the State of Maryland as far as Bladensburg. It was merged into the Military Division of the Potomac on July 25, 1861. Later it was recreated on February 2, 1863 as the consolidated Department of Washington and 22nd Army Corps. It was again made the Department of Washington in 1865 and that command remained until 1869 when it was disbanded.
Commander, Department of Washington (1861) 
Commander, Department of Washington and 22nd Army Corps 
Commander, Department of Washington (1865-1869) 
- ^ Frederick H. Dyer, A Compendium of the War of the Rebellion (New York: T. Yoseloff, 1959; originally published Des Moines, IA: The Dyer Pub. Co., 1908), Vol. 1, pp. 254-257
- Eicher, John H., & Eicher, David J., Civil War High Commands, Stanford University Press, 2001, ISBN 0-8047-3641-3.
- National Archives, Guide to Federal Records; Records of United States Army Continental Commands, 1821-1920 (Record Group 393), 1817-1940 (bulk 1817-1920)