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Commanded by Major General George B. McClellan
On May 18, 1862, the Third and Fourth Corps gave up one of their three divisions to serve as the nucleus of a re-created Fifth Corps and a newly-created Sixth Corps.
| Headquarters | ||
| Second Corps | Brigadier General Edwin V. Sumner (to Maj. Gen. 5/5) | |
| First Division | Brigadier General Israel B. Richardson | |
| Second Division | Brigadier General John Sedgwick | |
| Third Corps | Brigadier General Samuel P. Heintzelman (to Maj. Gen. 5/5) | |
| First Division | Brigadier General Fitz John Porter | to 5 Corps, 1 Div. (below) |
| Second Division | Brigadier General Joseph Hooker | |
| Third Division | Brigadier General Philip Kearney | |
| Fourth Corps | Brigadier General Erasmus Keyes | |
| First Division | Brigadier General Darius N. Couch | |
| Second Division | Brigadier General William F. Smith | to 6 Corps, 2 Div. (below) |
| Third Division | Brigadier General Silas Casey | |
| Fifth Corps | Brigadier General Fitz John Porter | recreated 5/18 |
| First Division | Brigadier General George W. Morrell (to 6/30) | from 3 Corps, 1 Div. (above) |
| Second Division | Brigadier General George Sykes | |
| Artillery Reserve | Colonel Henry J. Hunt | from unattached (below) |
| Sixth Corps | Major General William B. Franklin | |
| First Division | Brigadier General Henry Slocum | from Dept. Rappahannock, 1 Div. |
| Second Division | Brigadier General William F. Smith | from 4 Corps, 2 Div. (above) |
| Cavalry Reserve | Brigadier General Philip St. George Cooke | |
| First Brigade | Colonel William H. Emory | |
| Second Brigade | Colonel George A. H. Blake | |
| Artillery Reserve | Colonel Henry J. Hunt | to 5th Corps (above) |