Second Bull Run Union order of battle

The following Union Army units and commanders fought in the Second Battle of Bull Run, also known as the Second Battle of Manassas, of the American Civil War. The Confederate order of battle is listed separately. Order of battle compiled from the army organization during the battle, the casualty returns and the reports.
Union forces.
Army of Virginia.
MG John Pope
Chief of Staff: Col George D. Ruggles
Chief of Artillery: Cpt Alexander Piper
Chief of Cavalry: BG Washington L. Elliott (w)
Headquarters Escort:
I Corps.
MG Franz Sigel (w)
Chief of Artillery: Cpt Ulric Dahlgren
Headquarters Escort:
III Corps.
MG Irvin McDowell
Chief of Staff: Col Edmund Schriver
Chief of Artillery: Maj Davis Tillson
Headquarters Troops:
Reserve Corps.
BG Samuel D. Sturgis
Army of the Potomac.
The following Corps from the Army of the Potomac were "attached" to the Army of Virginia.
III Corps.
MG Samuel P. Heintzelman
V Corps.
MG Fitz John Porter
Chief of Staff: Ltc Frederick T. Locke
IX Corps.
MG Jesse L. Reno