Organized for one year August, 1864, by consolidation of 3rd, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, 15th and 16th Unattached Companies Heavy Artillery. Attached to 2nd Brigade, Hardin's Division, 22nd Army Corps, Dept. of Washington, and engaged in garrison duty in the Defences of Washington, north of the Potomac, to September, 1865. (For Co. "I," 13th Unattached Company, see 13th Unattached Company.) Mustered out September 18, 1865.
Regiment lost during service 2 Enlisted men killed and 1 Officer and 38 Enlisted men by disease. Total 41.