The United States Army in the Eastern Theater

< to February • March 1862 • to April >

Commanded by Major General George B. McClellan

Army of the Potomac
Major General George B. McClellan

Department of Virginia
Major General John E. Wool

Mountain Department (established March 11 from the Department of Western Virginia)
Brigadier General William S. Rosecrans (to March 29)
Major General John C. Fremont

Military District of Washington (established March 12)
Brigadier General James Wadsworth
Consisting of the District of Columbia, Alexandria, Virginia, and Fort Washington, Maryland

Middle Department (established March 22)
Major General John Dix
Consisting of New Jersey, Pennsylvania, Delaware and the Eastern Shore of Maryland and Virginia and the counties of Cecil, Hartford, Baltimore and Ann Arundel in Maryland.