Second Corps, Army of Northern Virginia General Gustavus W. Smith. This unit was also known as the Second Division and was eventually subsumed into general Robert E. Lee's Army of Northern Virginia as a reserve in Maj. Gen. D. H. Hill's Division. When Lee was able to reorganize his army after finishing battles with Union Maj. Gen. George B. McClellan on the peninsula, he created this corps under the command of Lieutenant General Jackson, along with a sister corps under Lt. Gen. James Longstreet. Lee's reorganization was based on his evaluation of the performance of his division commanders during the Seven Days Campaign. General Jackson commanded
Army of Northern Virginia Gen. J. E. Johnston as it was joined by the Army of the Shenandoah on July 20, 1861, when command was relinquished to General J. E. Johnston. The following day this army fought its first major engagement in the First Battle of Manassas. With the merging of the Army of the Shenandoah, Gen. Joseph E. Johnston took command from July 20, 1861, until May 31, 1862. Under the command of Johnston, the Army immediately entered into the First Battle of Manassas. On October 22, 1861, the Department of Northern Virginia was officially created, officially ending the Army of the Potomac.