It served in the eastern theater, predominantly in the VI Corps, Army of the Potomac, from June 1861 to July 1865.

In July 1861, the United States Congress authorized President Abraham Lincoln to call out 500,000 men, to serve for three years unless sooner discharged.

It was organized from militia companies from Brattleboro, Burlington, Castleton, Fletcher, Ludlow, Montpelier, Tunbridge, Vergennes and Waterbury.

[1] The colonelcy of the regiment was initially offered to Israel B. Richardson, a native of Vermont, but he had just accepted command of the 1st Michigan Infantry.

Richardson recommended a classmate from the United States Military Academy, Henry H. Whiting, and he was commissioned by Governor Erastus Fairbanks on June 6, 1861.

Commanders Lieutenant Colonels Majors Adjutants Quartermasters Surgeons Assistant-Surgeons ChaplainsIts assignments are as follows:[10] The official list of battles in which the regiment bore a part:[11][12] The 2nd Vermont's detailed service is as follows[17] During the course of the war, a total of 1,858 men served in the 3rd Vermont Infantry with 866 original recruits and 992 gains from recruiting and transfer.