Antietam Union order of battle

The following Union Army units and commanders fought in the Battle of Antietam of the American Civil War. The Confederate order of battle is listed separately. Order of battle compiled from the army organization during the Maryland Campaign, the casualty returns and the reports.
Army of the Potomac.
MG George McClellan
General Staff and Headquarters.
General Staff
General Headquarters
Escort: Cpt James B. McIntyre
U.S. Engineer Battalion: Cpt James C. Duane
Provost Guard: Maj William H. Wood
Headquarters Guard: Maj Granville O. Haller
Quartermaster's Guard: 
I Corps.
MG Joseph Hooker (w)
<br>
BG George G. Meade
Escort: 
II Corps.
MG Edwin V. Sumner
Escort:
V Corps.
MG Fitz John Porter
Escort:
VI Corps.
MG William B. Franklin
Escort:
IX Corps.
MG Ambrose Burnside 
<br>
BG Jacob D. Cox
Escort:
XII Corps.
MG Joseph K. Mansfield (mw)
<br>
BG Alpheus S. Williams
Escort: