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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 | ||
| First Corps | Major General Joseph Hooker (w 9/17) Brig. Gen. George Meade (to 9/29) Brig. Gen. John F. Reynolds |
|
| 1st Division | Brig. Gen. Rufus King Brig. Gen. J.P. Hatch (w 9/14) Brig. Gen. Abner Doubleday |
recreated from Army of Virginia, 3rd Corps |
| 2nd Division | Brigadier General J. B. Ricketts | |
| 3rd Division | Brig. Gen. George Meade (to 9/17) Brig. Gen. Truman Seymour (to 9/29) Brig. Gen. George Meade |
|
| Second Corps | Major General Edwin V. Sumner | |
| 1st Division | Brig. Gen. Israel Richardson (mw 9/17) Brig. Gen. John C. Caldwell (9/17) Brig. Gen. Winfield S. Hancock |
|
| 2nd Division | Brig. Gen. John Sedgwick (w 9/17) Brig. Gen. Oliver O. Howard |
|
| 3rd Division | Brigadier General William H. French | created 9/10 |
| Third Corps | Major General Samuel P. Heintzelman | |
| 1st Division | Brig. Gen. Philip Kearney (k 9/1) Brig. Gen. David B. Birney (to 9/13) Brig. Gen. George Stoneman |
|
| 2nd Division | Brig. Gen. Joseph Hooker (to 9/5) Brig. Gen. Daniel Sickles |
|
| Fourth Corps | Brigadier General Erasmus Keyes | |
| 1st Division | Brig. Gen. Darius N. Couch | to 6th Corps 9/26 (below) |
| 2nd Division | Brig. Gen. J. J. Peck | to Dept. of Virginia 9/26 |
| Fifth Corps | Major General Fitz John Porter | |
| 1st Division | Brig. Gen. George W. Morrell | |
| 2nd Division | Brig. Gen. George Sykes | |
| 3rd Division | Brig. Gen. Andrew A. Humphreys | recreated 9/12 |
| Sixth Corps | Major General William B. Franklin | |
| 1st Division | Brig. Gen. Hennry W. Slocum | |
| 2nd Division | Brig. Gen. William F. Smith | |
| 3rd Division | Brig. Gen. 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) Brig. Gen. Jacob D. Cox |
|
| 1st Division | Bde. Gen. Isreal I. Stevens (k 9/1) Col. B. C. Christ (to 9/8) Bde. Gen. Orlando Wilcox |
|
| 2nd Division | Major General Jesse Reno (to 9/3) Brig. Gen. Samuel D. Sturgis |
|
| 3rd Division | Major Gen. J. G. Parke (to 9/3) Brig. Gen. I. P. Rodman (mw 9/17) Major Gen. J. 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 | Bde. Gen. Julius H. Stahel | created 9/12 from Army of Virginia, 1st Corps |
| 2nd Division | Bde. Gen. Adolph Von Steinwehr | |
| 3rd Division | Brig. Gen. Carl Schurz | |
| Twelfth Corps |
Major Gen. J. F. K. Mansfield (mw 9/17) Brigadier General Alpheus S. Williams |
|
| 1st Division | Brig. Gen. Alpheus Williams (to 9/17) Brig. Gen. Samuel W. Crawford (w 9/17) Brig. Gen. George Gordon |
created 9/12 from |
| 2nd Division | Brigadier General George Greene | |
| Cavalry Division | Brigadier General George Stoneman (to 9/13) Brigadier General Alfred Pleasonton |
|
| 1st Brigade | Colonel W. W. Averill (to 9/13) Major C. Whiting |
|
| 2nd Brigade | Brig. Gen. 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 | |