Men were recruited under the calls of President Lincoln on 15 April 1861 and Governor Buckingham the following day[1][2] Many Connecticut residents had anticipated a call to arms, and, as a result, several companies had already reached their manpower requirements by the 16th.

[3] The regiment left for Washington, D.C., on 18 May on the steamer Bienville and served at Fort Corcoran as part of the capitol garrison.

The regiment was assigned to Key's 1st Brigade, Tyler's Division, McDowell's Army of Northeastern Virginia on 1 June and advanced to Vienna and Falls Church in northern Virginia between 1 and 8 June.

The regiment fought in the First Battle of Bull Run on 21 July, and was lauded for maintaining discipline during the retreat of the Union troops.

[4] During the unit's service, 6 men were wounded, 6 were captured, and 25 were discharged for disability.