August 1861 • to September >
Commanded by Major General John Dix
On August 24 the Department of Pennsylvania merged with the Department of the Potomac. Dix’s Division, headquartered in Baltimore, had been the troops of the Department of Annapolis, who were redesignated Department of Maryland on July 19, merged into the Department of Pennsylvania on July 25 and then into the Army of the Potomac.
| Infantry | ||
| 1st Delaware Militia | Colonel Henry H. Lockwood | mustered out 8/30 |
| 20th Indiana Infantry Regiment | Colonel William L. Brown | |
| 21st Indiana Infantry Regiment | Colonel James W. McMillan | |
| 17th Massachusetts Infantry Regiment | Colonel Thomas I.C. Amory | from Lynnfield, Ma. 8/23 |
| 7th Maine Infantry Regiment | Colonel Thomas H. Marshall | From Augusta, Me., 8/23 |
| 3rd New York Infantry Regiment | Lt. Colonel Samuel M. Alford | promoted colonel 8/26 |
| 4th New York Infantry Regiment | Colonel Alfred W. Taylor | |
| 5th New York Infantry Regiment | Colonel C. Schwartzwaelder | |
| 1st Pennsylvania Reserves | Colonel R. Biddle Roberts | to 1 Brig., McCall’s Div. 8/30 |
| 19th Pennsylvania Infantry Regiment | Colonel Peter Lyle | to Philadelphia to muster out 8/29 |
| Artillery & Cavalry | ||
| 2nd United States Artillery, Battery I | at Fort McHenry | |
| 1st Maryland Cavalry Regiment | Colonel Andrew G. Miller | Organized at Baltimore |