Before being converted into an artillery unit in 1863, it served as the 21st Regiment, Indiana Volunteer Infantry.

The regiment was attached to Dix's Division, Baltimore, Maryland, to February 1862.

Unattached, 1st Division, XIX Corps, Department of the Gulf, to February 1863.

District of Baton Rouge, Louisiana, Department of the Gulf, to June 1864.

The 1st Indiana Heavy Artillery mustered out January 10, 1866, at Baton Rouge, Louisiana.

Left Indiana for Baltimore, Maryland, July 31, and duty in the defenses of that city until February 19, 1862.

Moved to Newport News, Virginia, February 19, 1862; then sailed on the steamer Constitution for Ship Island, Mississippi, March 4–13.

Expedition from Carrollton to St. Charles Court House September 7–8.

Action with steamer Cotton, Bayou Teche, January 14, 1863.

Garrison duty at New Orleans, Baton Rouge, and at various points in the Department of the Gulf until February 1865.

Monett's Ferry, Cane River Crossing, April 23 (detachment).

Operations in Mobile Bay, Alabama, against Forts Gaines and Morgan August 2–23 (Companies B, F, H, and K).