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

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.

Army of the Potomac

Dept. of Virginia

Middle Department

Mountain Department
(to the west of the
Army of the Potomac)