Organization of the Army of the Potomac — Major-General George G. Meade
First Corps
John F. Reynolds, Major General
John Newton, Major General
| Divisions | Brigades |
| 1. James S. Wadsworth | 1. Solomon Meredith, Brig. Gen. |
| Brigadier General | 2. Lysander Cutler, Brig. Gen. |
| 2. John C. Robinson | 1. Gabriel R. Paul, Brig. Gen. |
| Brigadier General | 2. Henry Baxter, Brig. Gen. |
| 3. Abner Doubleday | 1. Thomas Rowley, Brig. Gen. |
| Major General | 2. Roy Stone, Col. |
| 3. George J. Stannard, Brig. Gen. |
Second Corps
Winfield S. Hancock, Major General
| Divisions | Brigades |
| 1. John C. Caldwell | 1. Edward E. Cross, Col. |
| Brigadier General | 2. Patrick Kelly, Col. |
| 3. Samuel K. Zook, Brig. Gen. | |
| 4. John R. Brooke, Col. | |
| 2. John Gibbon | 1. William Harrow, Brig. Gen. |
| Brigadier General | 2. Alexander Webb, Brig. Gen. |
| 3. Norman J. Hall, Col. | |
| 3. Alexander Hays | 1. Samuel S. Carroll, Col. |
| Brigadier General | 2. Thomas A. Smyth, Col. |
| 3. George L. Willard, Col. |
Third Corps
Daniel E. Sickles, Major General
| Divisions | Brigades |
| 1. David D. Birney | 1. Charles K. Graham, Brig. Gen. |
| Major General | 2. J. H. Hobart Ward, Brig. Gen. |
| 3. Regis de Trobriand, Col. | |
| 2. Andrew A. Humphreys | 1. Joseph B. Carr, Brig. Gen. |
| Brigadier General | 2. Wm. R. Brewster, Col. |
| 3. George C. Burling, Col. |
Fifth Corps
George Sykes, Major General
| Divisions | Brigades |
| 1. James Barnes | 1. William S. Tilton, Col. |
| Brigadier General | 2. Jacob B. Sweitzer, Col. |
| 3. Strong Vincent, Col. | |
| 2. George Sykes | 1. Hannibal Day, Col. |
| Major General | 2. Sidney Burbank, Col. |
| Romeyne B. Ayres | 3. Stephen Weed, Brig. Gen. |
| Brigadier General | |
| 3. Samuel W. Crawford | 1. William McCandless, Col. |
| Brigadier General | 2. Joseph W. Fisher, Col. |
Sixth Corps
John Sedgwick, Major General
| Divisions | Brigades |
| 1. Horatio G. Wright | 1. Alfred T. A. Torbet, Brig. Gen. |
| Brigadier General | 2. Joseph J. Bartlett, Brig. Gen. |
| 3. David A. Russell, Brig. Gen. | |
| 2. Albion P. Howe | 1. Lewis A. Grant, Col. |
| Brigadier General | 2. Thomas H. Neill, Brig. Gen. |
| 3. John Newton | 1. Alexander Shaler, Brig. Gen. |
| Major General | 2. Henry L. Eustis, Col. |
| Frank Wheaton | 3. Frank Wheaton, Brig. Gen. |
| Brigadier General |
Eleventh Corps
Oliver O. Howard, Major General
| Divisions | Brigades |
| 1. Francis C. Barlow | 1. Leopold von Gilsa, Col. |
| Brigadier General | 2. Adelbert Ames, Brig. Gen. |
| 2. Adolph von Steinwehr | 1. Charles Coster, Col. |
| Brigadier General | 2. Orlando Smith, Col. |
| 3. Carl Schurz | 1. Alexander Schimmelfennig, Brig. Gen. |
| Major General | 2. W. Krzyzanowski, Col. |
Twelfth Corps
Henry W. Slocum, Major General
| Divisions | Brigades |
| 1. Alpheus S. Williams | 1. Archibald L. McDougal, Col. |
| Brigadier General | 2. Henry H. Lockwood, Brig. Gen. |
| 3. Thomas H. Huger, Brig. Gen. | |
| 2. John W. Geary | 1. Charles Candy, Col. |
| Brigadier General | 2. George A. Cobham, Col. |
Cavalry
Alfred Pleasanton, Major General
| Divisions | Brigades |
| 1. John Buford | 1. William Gamble, Col. |
| Brigadier General | 2. Thomas C. Devin, Col. |
| 3. Wesley Merritt, Brig. Gen. | |
| 2. David McM. Gregg | 1. John B. McIntosh, Col. |
| Brigadier General | 2. Pennock Ruey, Col. |
| 3. J. Irvin Gregg, Col. | |
| 3. Judson Kilpatrick | 1. Elon J. Farnsworth, Brig. Gen. |
| Brigadier General | 2. George A. Custer, Brig. Gen. |
Chief of Artillery, Brigadier-General Henry J. Hunt
Number of guns belonging to the Artillery, 362
Number of guns at Gettysburg, 354