United States Armies in the East
March 1862 – August 1865
Designated 22nd Army Corps July 1862
The department was created on March 22, 1862 to consist of New Jersey, Pennsylvania, Delaware, the Eastern Shores of Maryland and Virginia, and Ann Arundel, Baltimore, Cecil and Harford Counties in Maryland. The composition of the department was adjusted several times throughout the war due to changing conditions.
Monthly Organization of the Middle Department
1862: March, April, May, June, July, August, September, October, November, December
1863: January, February, March, April, May, June, July, August, September, October, November, December
1864: January, February, March, April, May, June, July, August, September, October, November, December
1865: January, February, March, April, May, June, July
Timeline of the Middle Department
| 1862 | |
| March 22 | Department established under Major General John Dix, with headquarters in Baltimore. |
| June 9 | Major General John Wool took command of the Department |
| July 22 | Departmental troops organized as the 22nd Army Corps |
| December 22 | Major General Robert C. Schenck took command of the Department |
| 1863 | |
| March | West Virginia added to the Department |
| March 12-22 | Brigadier General William W. Morris took temporary command of Department |
| August 10-31 | Brigadier General W. W. Morris took temporary command of Department |
| September 22-28 | Brigadier General W. W. Morris took temporary command of Department |
| September 28- October 10 |
Brigadier General Erastus B. Tyler took temporary commend of Department |
| December 5 | Brigadier General H. H. Lockwood took command of the Department |
| 1864 | |
| March 22 | Major General Lew Wallace took command of Department |
| July 9, | Battle of Monocacy. General Wallace delayed the invading Confederate army of Jubal Early long enough for the Washington defences to be manned by veteran troops from Grant’s army |
| 1865 | |
| August 1 | Department abolished |