< to August • September 1862

Commanded by Colonel Henry K. Hunt

After the Battle of Antietam the Artillery Reserve was broken up and its batteries assigned at the corps and division level. Colonel Hunt was promoted to brigadier general and joined the headquarters staff in a primarily administrative role.

First Brigade Horse Artillery
2nd United States Artillery, Battery A  to Cavalry Division
2nd United States Artillery, Batteries B&L
2nd United States Artillery, Battery M
3rd United States Artillery, Batteries C&G
Second Brigade 
1st United States Artillery, Battery E to 2 Div. Artillery
1st United States Artillery, Battery G to 2 Div. Artillery
1st United States Artillery, Battery K
4th United States Artillery, Battery G to Corps Reserve Artillery
5th United States Artillery, Battery A to 9 Corps, 3 Div. Artillery
5th United States Artillery, Battery K to 2 Div. Artillery
Third Brigade 
1st New York Artillery Bn., Battery A Captain Thomas H. Bates to 5 Corps Reserve Artilery
1st New York Artillery Bn., Battery B Captain Rufus T. Pettit
1st New York Artillery Bn., Battery C
1st New York Artillery Bn., Battery D Captain Thomas W. Osborn
Fourth Brigade
Maryland Artillery, Battery A to 6 Corps, 1 Div. Artillery
Maryland Artillery, Battery B to 6 Corps, 2 Div. Artillery
Fifith Brigade
2nd United States Artillery, Battery E to 9 Corps, 1 Div. Artillery
3rd United States Artillery, Batteries F&K to 3 Corps, 1 Div. Artillery
Unattached
5th New York Independent Battery to 5 Corps Reserve Artillery