The United States Army in the Eastern Theater

< to June • July 1861 • to August >

Commanded by Major General Winfield Scott

Department of Washington 
Colonel Joseph K. F. Mansfield
Merged into the Military District of the Potomac 7/25.

Department of Pennsylvania
Major General Robert Patterson (to 7/27)
Major General John A. Dix

Department of Annapolis 
Renamed Department of Maryland 7/19
Merged into Dept. of Pennsylvania 7/25
Major Gen. Nathaniel Banks (to 7/19)
Major General John A. Dix (7/19 -7/25)

Department of Virginia
Major General Benjamin F. Butler

Department of Northeastern Virginia
Brigadier General Irvin McDowell

Military District of the Potomac (created 7/25)
Major General George B. McClellan
Combined the Departments of Maryland, Washington and Northeastern Virginia

Dept. of the Shenandoah (created 7/19)
Major General Nathaniel P. Banks
To consist of the Valley of Virginia, and Washington & Allegheny Counties in Maryland

Department of the East (Pre-war)
Major General John E. Wool

Dept. of Washington
Dept. of Pennsylvania
Dept. of Annapolis

Dept. of Virginia

Dept. of N.E. Virginia

Department of the Shenandoah