< to July • August 1862 • to September >
Commanded by Brigadier General James Wadsworth
| Defenses North of the Potomac | Lieutenant Colonel Joseph A. Haskin | |
| 18th Maine Infantry Regiment | Colonel Daniel Chaplin | from Maine |
| 19th Maine Infantry Regiment | Colonel Frederick D. Sewel | from Maine |
| 17th Michigan Infantry Regiment | Colonel William Withington | from Michigan; to 1 Brig. 1 Div. 9 Corps, Army Potomac |
| 113th New York Infantry Regiment | Colonel Lewis O. Morris | from New York |
| 117th New York Infantry Regiment | Colonel William R. Pease | from New York |
| 135th Pennsylvania Infantry Regiment | Colonel James R. Porter | from Pennsylvania |
| 136th Pennsylvania Infantry Regiment | Colonel Thomas M. Bayne | from Pennsylvania |
| 5th Battalion New York Heavy Artillery | from New York | |
| 6th Battalion New York Heavy Artillery | from New York | |
| 7th Battalion New York Heavy Artillery | from New York | |
| 2nd Pennsylvania Heavy Artillery | Colonel Augustus A. Gibson | from unassigned artillery (below) |
| Casey’s Provisional Brigade | Major General Silas Casey | created Aug. |
| 15th Connecticut Infantry Regiment | Colonel Dexter R. Wright | from New Haven 8/28 |
| Keystone (PA) Battery | from Philadelphia | |
| Sturgis’ Brigade | Brigadier General Samuel Sturgis | dissolved at end of month |
| 9th Rhode Island Infantry Regiment | Colonel Charles T. Robbins | mustered out 9/2 |
| 10th Rhode Island Infantry Regiment | Colonel Zenas R. Bliss | mustered out 9/1 |
| 71st New York State Militia | Colonel Henry P. Martin | mustered out 9/2 |
| 63rd Indiana Infantry (4 companies) | to Whipple’s Div., Piatt’s Brig. (below) | |
| 19th United States Infantry, 1st Bn. | to 2 Brig. 2 Div. 5 Corps, Army Potomac | |
| 8th Massachusetts Battery | to 9th Corps artillery | |
| Whipple’s Brigade/Division | Brigadier General Amiel W. Whipple | expanded to a division |
| Piatt’s Brigade | Brigadier General Abram S. Piatt | |
| 86th New York Infantry Regiment | Colonel Benajah P. Bailey | from unassigned infantry (below) |
| 124th New York Infantry Regiment | Colonel A. Van Horne Ellis | from Washington September |
| 122nd Pennsylvania Infantry Regiment | Colonel Emlen Franklin | from Pennsylvania |
| 63rd Indiana Infantry (4 companies) | from Sturgis’ Brigade (above) | |
| Unassigned units | ||
| 14th Connecticut Infantry Regiment | Colonel Dwight Morris | from Connecticut |
| 16th Maine Infantry Regiment | from Maine | |
| 1st Massachusetts Heavy Artillery | ||
| 35th Massacusetts Infantry Regiment | Colonel Edward A. Wild | from Massachusetts |
| 9th New Hampshire Infantry Regiment | Colonel Enoch Q. Fellows | from New Hampshire |
| 11th New Jersey Infantry Regiment | Colonel Robert McAllister | from New Jersey |
| 2nd New York Heavy Artillery Regiment | Colonel Gustave Wagner | |
| 4th New York Heavy Artillery Regiment | Colonel Gustavus A. DeRussy | |
| 11th New York Independent Battery | ||
| 12th New York Independent Battery | ||
| 107th New York Infantry Regiment | Colonel Robert B. Van Valkenburgh | from New York |
| 108th New York Infantry Regiment | Colonel Oliver H. Palmer | from New York |
| 120th New York Infantry Regiment | Colonel George H. Sharpe | from New York |
| 124th Pennsylvania Infantry Regiment | Colonel Joseph W. Hawley | from Pennsylvania |
| 125th Pennsylvania Infantry Regiment | Colonel Jacob C. Higgins | from Pennsylvania |
| 127th Pennsylvania Infantry Regiment | Colonel William W. Jennings | from Pennsylvania |
| 128th Pennsylvania Infantry Regiment | Colonel Samuel Croasdale | from Pennsylvania |
| 130th Pennsylvania Infantry Regiment | Colonel Henry I. Zinn | from Pennsylvania |
| 131st Pennsylvania Infantry Regiment | Colonel Peter H. Allabach | from Pennsylvania |
| 132nd Pennsylvania Infantry Regiment | Colonel Richard A Oakford | from Pennsylvania |
| Wrigley’s Pennsylvania Engineer Company | Captain H.E. Wrigley | from Pennsylvania |
| 1st Wisconsin Heavy Artillery | ||
| Infantry | ||
| 2nd District of Columbia Infantry Regt. | ||
| 19th Maine Infantry Regiment | Colonel Frederick D. Sewell | from Maine |
| 34th Massachusetts Infantry Regiment | Colonel George D. Wells | from Maine |
| 10th New Jersey Infantry Regiment | Colonel William R. Murphy | |
| 69th New York State Militia | Colonel James Bagley | mustered out |
| 86th New York Infantry Regiment | Colonel Benajah P. Bailey | to Piatt’s Brig. Whipple’s Div. (above) |
| 91st Pennsylvania Infantry Regiment | Colonel Edgar M. Gregory | to 5th Corps, 3rd Div., 1st Brig. |
| 135th Pennsylvania Infantry Regiment | Colonel James R. Porter | from Pennsylvania |
| 136th Pennsylvania Infantry Regiment | Colonel Thomas M. Bayne | from Pennsylvania |
| 143rd Pennsylvania Infantry Regiment | Colonel Edmund L. Dana | from Pennsylvania |
| 149th Pennsylvania Infantry Regiment | Colonel Roy Stone | from Pennsylvania |
| Artillery | ||
| 1st Connecticut Heavy Artillery | from Army Potomac siege artillery | |
| 1st New York Artillery, Battery C | ||
| 9th New York Independent Battery | ||
| 16th New York Independent Battery | ||
| 17th New York Independent Battery | from New York October | |
| 1st Ohio Artillery, Battery H | ||
| 2nd Pennsylvania Heavy Artillery | Colonel Augustus A. Gibson | to Defenses N. of Potomac (above) |
| 10th Rhode Island Battery | mustered out 8/30 | |
| West Virginia Artillery, Battery A | ||
| West Virginia Artillery, Battery B | ||
| Cavalry | ||
| 6th New York Cavalry Regiment | Colonel Thomas C. Devin | to 9th Corps, Army Potomac |
| 11th New York Cavalry Regiment | Colonel James B. Swain | |
| 12th Pennsylvania Cavalry Regiment | Colonel Lewis B. Pierce | to 4 Brig. Pleasanton’s Cav. Div. Army Potomac |