Battle of Antietam order of battle: Union

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.

Military rank

 * MG = Major General
 * BG = Brigadier General
 * Col = Colonel
 * Ltc = Lieutenant Colonel
 * Maj = Major
 * Cpt = Captain
 * Lt = Lieutenant

Other

 * w = wounded
 * mw = mortally wounded
 * k = killed in action
 * c = captured

Army of the Potomac
MG George McClellan

General Staff and Headquarters
General Staff
 * Chief of Staff: BG Randolph B. Marcy
 * Assistant Adjutant General: BG Seth Williams
 * Inspector General: BG Delos B. Sackett
 * Chief of Artillery: BG Henry J. Hunt
 * Chief Quartermaster: Ltc Rufus Ingalls

General Headquarters

Escort: Cpt James B. McIntyre
 * Independent Company Oneida (New York) Cavalry: Cpt Daniel P. Mann
 * 4th United States Cavalry, Company A: Lt Thomas H. McCormick
 * 4th United States Cavalry, Company E: Cpt James B. McIntyre

U.S. Engineer Battalion: Cpt James C. Duane

Provost Guard: Maj William H. Wood
 * 2nd United States Cavalry, Companies E, F, H, and K: Cpt George A. Gordon
 * 8th United States, Companies A, D, F, and G: Cpt Royal T. Frank
 * 19th United States, Company G: Cpt Edmund L. Smith
 * 19th United States, Company H: Cpt Henry S. Welton

Headquarters Guard: Maj Granville O. Haller
 * 93rd New York: Ltc Benjamin C. Butler

Quartermaster's Guard:
 * 1st United States Cavalry, Companies B, C, H, and I: Cpt Marcus A. Reno

I Corps
MG Joseph Hooker (w) BG George G. Meade

Escort:
 * 2nd New York Cavalry, Companies A, B, I and K: Cpt John E. Naylor

II Corps
MG Edwin V. Sumner

Escort:
 * 6th New York Cavalry, Company D: Cpt Henry W. Lyon
 * 6th New York Cavalry, Company K: Cpt Riley Johnson

V Corps
MG Fitz John Porter

Escort:
 * 1st Maine Cavalry (detachment): Cpt George J. Summat

VI Corps
MG William B. Franklin

Escort:
 * 6th Pennsylvania Cavalry, Companies B and G: Cpt Henry P. Muirheid

IX Corps
MG Ambrose Burnside BG Jacob D. Cox

Escort:
 * 1st Maine Cavalry, Company G: Cpt Zebulon B. Blethen

XII Corps
MG Joseph K. Mansfield (mw) BG Alpheus S. Williams

Escort:
 * 1st Michigan Cavalry, Company L: Cpt Melvin Brewer