The Army of Virginia was constituted on June 26, 1862, by General Orders Number 103, from four existing departments operating around Virginia: Maj. Gen. John C. Frémont's Mountain Department, Maj. Gen. Irvin McDowell's Department of the Rappahannock, Maj. Gen. Nathaniel P. Banks's Department of the Shenandoah, and Brig. Gen. Samuel D. Sturgis's brigade from the Military District of Washington. Maj. Gen. John Pope commanded the new organization, which was divided into three corps of over 50,000 men. Three corps of Maj. Gen. George B. McClellan's Army of the Potomac later were added for combat operations.
Radical Republicans in Congress and the Cabinet saw the Army of Virginia as taking the lead in widening the goals of the war. The senior officers of the Army were stronger advocates of the abolition of slavery and the southern way of life and had a smaller proportion of West Point graduates than the contemporary Army of the Potomac.[1]
The entire army was soundly defeated at the Second Battle of Bull Run by Jackson, Longstreet, and Lee, and withdrew to the defensive lines of Washington, D.C. On September 12, 1862, the units of the Army of Virginia were merged into the Army of the Potomac and the Army of Virginia was never reconstituted.
The first three corps were given numeric designations that overlapped with those in the Army of the Potomac. They were redesignated as shown for the Maryland Campaign and later.
I Corps, Army of Virginia; commanded by Franz Sigel (this corps had been the Mountain Department under John Frémont; it eventually became the XI Corps, Army of the Potomac)
II Corps, Army of Virginia; commanded by Nathaniel Banks (formerly known as V Corps and Department of the Shenandoah; later known as XII Corps, Army of the Potomac)
III Corps, Army of Virginia; commanded by Irvin McDowell (formerly known as I Corps and Department of the Rappahannock; reverted to I Corps, Army of the Potomac)
^Matsui, John H. (June 2012), "War in Earnest: The Army of Virginia and the Radicalization of the Union War Effort, 1862", Civil War History, 58 (2): 185–187
Boatner, Mark M. III, The Civil War Dictionary: Revised Edition, David McKay Company, Inc., 1984, ISBN0-679-73392-2.