The following Union Army units and commanders were the initial structure on April 4, 1862 of the Union Department of the Potomac during the Peninsula Campaign of the American Civil War. It contains units both deployed to the Virginia Peninsula and those remaining in the Washington area. The Confederate order of battle is listed separately.
Contents
Military rank
Army of the Potomac
The following units were the initial organization of the Army of the Potomac on the Peninsula.
MG George B. McClellan, Commanding
Headquarters and Body Guard
Provost Guard
Staff
Col Randolph B. Marcy, Chief of Staff
Maj Granville O. Haller, Commandant of General Headquarters
Second Corps
BG Edwin Sumner, Commanding
Ltc Joseph H. Taylor, Adjutant
N.B. The Third Division under BG Louis Blenker was detached in early April and transferred to the Mountain Department
Third Corps
BG Samuel P. Heintzelman, Commanding
Cpt Chauncey McKeever, Chief of Staff
Porter's Division was combined with Sykes' Division of the Reserve Corps and McCall's Division of the First Corps to form the Fifth Corps (Provisional) on May 18, 1862.
Fourth Corps
BG Erasmus D. Keyes, Commanding
Ltc Charles C. Suydam
W.F. Smith's Division was combined with Franklin's Division of the First Corps to form the Sixth Corps (Provisional) on May 18, 1862.
Reserves
Sykes' Division was combined with Porter's Division of the Third Corps and McCall's Division of the First Corps to form the Fifth Corps (Provisional) on May 18, 1862.
Other Troops from the Department of the Potomac
The following troops were part of the Department of the Potomac in March and April 1861, but were detached to maintain defense of the Potomac River line.
First Corps
On April 4, the First Corps was renamed the Department of the Rappahannock, with authority to include the District of Columbia, Maryland between the Potomac and Patuxent, and Virginia between the Blue Ridge and the Fredericksburg & Richmond Railroad.
MG Irvin McDowell, Commanding
Ltc Edmund Schriver, Chief of Staff
Unattached Cavalry
Sharpshooters
McCall's Division transferred to the Peninsula and was combined with Porter's Division of the Third Corps and Sykes' Division of the Reserve Corps to form the Fifth Corps (Provisional) on May 18, 1862. Franklin's Division transferred to the Peninsula and was combined with W.F. Smith's Division of the Fourth Corps to form the Sixth Corps (Provisional) on May 18, 1862.
Fifth Corps
On April 4, the Fifth Corps was renamed the Department of Shenandoah with authority over Maryland between the Blue Ridge and Flintstone Creek, Virginia between the Blue Ridge and the modern-day border with West Virginia.
MG Nathaniel P. Banks, Commanding
Cpt Louis H. Pelouze, Acting Assistant Adjutant General
Unattached Infantry
Shields' Division was transferred to the Department of the Rappahannock on May 10, 1862
District of Washington
BG James S. Wadsworth, Commanding
Railroad Guards
Col Dixon S. Miles
Troops Around Baltimore
On March 22, the Middle Department was created with authority over Pennsylvania, New Jersey, Delaware, and the Eastern Shore of Maryland and Virginia, as well as the Maryland counties of Cecil, Hartford, Baltimore, and Anne Arundel. Dix remained in command.
MG John A. Dix, Commanding
Maj Daniel T. Van Buren, Chief of Staff and Acting Assistant Adjutant General
Department of Virginia
The Department of Virginia constituted an area 60 miles from Fort Monroe. McClellan had received permission to absorb it into his army as a division of the First Corps, but it was rescinded shortly after he arrived on the Peninsula.
MG John E. Wool, Commanding