United States Army

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Commanded by Major General George B. McClellan

In September of 1862 most of the Army of the Potomac returned from the Virginia Peninsula to the Washington area. One division of the Fourth Corps was left behind and transferred to the Department of Virginia, while its other division was transferred to the 6th Corps. The three corps of the Pope’s badly defeated Army of Virginia merged into the Army of the Potomac as its First, Eleventh and Twelfth Corps. Thousands of new recruits joined, sometimes in entire brigades of raw and inexperienced men. The ink on the orders of new organization was not even dry before the army marched out of Washington on the campaign that culminated in the Battle of Antietam, the bloodiest single day in Civil War history.

Headquarters & Staff

Headquarters Staff
Chief of Staff Brigadier General Randolph B. Marcy
Chief of Artillery Brigadier General Henry J. Hunt
Chief of Cavalry Brigadier General John Buford
Chief Engineer Captain James C. Duane
Inspector General Colonel Delos B. Sacket
Assistant Adjutant General Lieutenant Colonel Albert V. Coburn
Chief Quartermaster Lieutenant Colonel Rufus Ingalls
Topographer Captain Charles R. Lowell
Medical Director Surgeon Jonathan Letterman
Chief of Signals Major Albert J. Meyer
Guards & Orderlies Captain James B. McIntyre
McClellan Dragoons (Illinois)
Sturgis (Illinois) Rifles
Oneida (New York) Cavalry Company Captain Daniel P. Mann
1st United States Cavalry, Cos. BCH&I Captain Marcus A. Reno
4th United States Cavalry, Cos. A & E Captain James B. McIntyre
Provost Guard Major William H. Wood
93rd New York Infantry, Cos. AFH&K Lieutenant Colonel Benjamin C. Butler
8th United States Infantry, Cos. ABDF&G Captain Royal T. Frank
19th United States Infantry Cos. G&H Captain Edmund L. Smith (Co. G)
Captain Henry S. Welton (Co. H)
2nd United States Cavalry Regiment Captain George Gordon
Engineer Brigade Brigadier General Daniel Woodbury
15th New York Engineer Regiment Colonel John M. Murphy
50th New York Engineer Regiment Lieutenant Colonel William H. Pettes
Regular Engineer Battalion Captain James C. Duane

First Corps

Major General Joseph Hooker (w 9/17)
Brigadier General George Meade (to 9/29)
Brigadier General John F. Reynolds
1st Division Brigadier General Rufus King
Brigadier General J.P. Hatch (w 9/14)
Brigadier General Abner Doubleday
recreated from
Army of Virginia, 3rd Corps
2nd Division Brigadier General J. B. Ricketts
3rd Division Brigadier General George Meade (to 9/17)
Brigadier General Truman Seymour (to 9/29)
Brigadier General George Meade

Second Corps

Major General Edwin V. Sumner
1st Division Brigadier General Israel Richardson (mw 9/17)
Brigadier General John C. Caldwell (9/17)
Brigadier General Winfield S. Hancock
2nd Division Brigadier General John Sedgwick (w 9/17)
Brigadier General Oliver O. Howard
3rd Division Brigadier General William H. French created 9/10

Third Corps

Major General Samuel P. Heintzelman
1st Division Brigadier General Philip Kearney (k 9/1)
Brigadier General David B. Birney (to 9/13)
Brigadier General George Stoneman
2nd Division Brigadier General Joseph Hooker (to 9/5)
Brigadier General Daniel Sickles

Fourth Corps

Brigadier General Erasmus Keyes
1st Division Brigadier General Darius N. Couch to 6th Corps 9/26 (below)
2nd Division Brigadier General J. J. Peck to Dept. of Virginia 9/26

Fifth Corps

Major General Fitz John Porter
1st Division Brigadier General George W. Morrell
2nd Division Brigadier General George Sykes
3rd Division Brigadier General Andrew A. Humphreys recreated 9/12

Sixth Corps

Major General William B. Franklin
1st Division Brigadier General Hennry W. Slocum
2nd Division Brigadier General William F. Smith
3rd Division Brigadier General Darius N. Couch from 4th Corps 9/26 (above)

Ninth Corps

Major General Ambrose Burnside (to 9/3)
Major General Jesse Reno (9/3 – mw 9/14)
Brigadier General Jacob D. Cox
1st Division Brigadier General Israel I. Stevens (k 9/1)
Colonel B. C. Christ (to 9/8)
Brigadier General Orlando Wilcox
2nd Division Major General Jesse Reno (to 9/3)
Brigadier General Samuel D. Sturgis
3rd Division Major Gen. J. G. Parke (to 9/3)
Brigadier General I. P. Rodman (mw 9/17)
Major General John G. Parke
Kanawha Division Brigadier General J. D. Cox (^ 9/14)
Colonel Eliakim Scammon
from Dept. West Virginia

Eleventh Corps

Major General Franz Sigel
1st Division Brigadier General Julius H. Stahel created 9/12 from
Army of Virginia, 1st Corps
2nd Division Brigadier General Adolph Von Steinwehr
3rd Division Brigadier General Carl Schurz

Twelfth Corps

Major General J. F. K. Mansfield (mw 9/17)
Brigadier General Alpheus S. Williams
1st Division Brigadier General Alpheus Williams (to 9/17)
Brigadier General Samuel W. Crawford (w 9/17)
Brigadier General George Gordon

created 9/12 from
Army of Virginia, 2nd Corps

2nd Division Brigadier General George Greene

Cavalry Division 

Brigadier General George Stoneman (to 9/13)
Brigadier General Alfred Pleasonton
1st Brigade Colonel William W. Averill  (to 9/13)
Major C. Whiting
2nd Brigade Brigadier General Alfred Pleasonton (to 9/13)
Colonel John F. Farnsworth
3rd Brigade Colonel Richard H. Rush
4th Brigade Colonel A. T. McReynolds
5th Brigade Colonel Benjamin F. Davis
Bayard’s Brigade Brigadier General G. D. Bayard