The regiment was formed by consolidation of multiple earlier recruiting efforts (Blair Rifles, Pratt Guards, Seymour Light Infantry, Burnside Rifles, Westchester Light Infantry, Defenders) into one unit.

Organization was completed in October, with some companies departing the state in June and September.

In November the regiment moved to Eastport, Mississippi, and in December became part of the XVI Corps.

It then participated in Nathaniel P. Banks' Red River campaign, taking part in multiple engagements (especially the Battle of Pleasant Hill).

[2] The regiment was consolidated into a single battalion back in Eastport in February, fought in the spring Mobile campaign in Alabama, and mustered out of service on April 20, 1866, at Montgomery, Alabama, under the command of Lieutenant Colonel John B. Gandolfo.