 The regiment was originally mustered-in for a three-month period of service between April and August 1861, but after its initial term of service had expired it was re-formed in September 1861 for a further three-year period, before being mustered out in September 1864.The companies of the 6th Indiana Volunteer Infantry were raised in different parts of the state and organized at Indianapolis, Indiana between April 22 and April 27, 1861.The companies' counties of origin included Jefferson, Bartholomew, Daviess, Howard, Henry, Jennings, Jackson, and Hamilton.