It mustered in the United States service at East New York for two years, June 3 and 8 (Company I), 1861.

Attached to:[10][1][2][3] The official list of battles in which the regiment bore a part:[11][1][2][3] [10] [10] [12] Regiment lost during service 3 Officers and 72 Enlisted men killed and mortally wounded and 3 Officers and 39 Enlisted men by disease.

[10] The regiment's bloodiest battles were First Bull Run, Williamsburg, Seven Days, and Fredericksburg.

[4][note 4] These rifles had been manufactured by the Harper's Ferry Arsenal and by contract in 1844 in Windsor, Vermont by the Robbins and Lawrence Armory (R&L)[14] which had also made the 1855 modifications of increasing the bore to .58 and fitting them with a sword bayonet.

[15][note 5] On July 7, 1861, companies A through F exchanged these rifles for rifle-muskets at the Washington DC arsenal.