Authorized in October 1864 at the Rock Island prisoner camp in Illinois as a one-year regiment, the 2nd U.S.V.I. was not organized until February 1865. It was ordered to the Department of the Missouri and sent by rail to Fort Leavenworth, Kansas, where it was assigned to duty in the District of Upper Arkansas along the Santa Fe Trail from the Little Arkansas River to Fort Dodge, Kansas, and along the Cimarron Crossing to Fort Lyon, Colorado. From Fort Leavenworth the unit marched to Fort Riley, and stationed companies there and at Salem, Fort Ellsworth, Fort Larned, Fort Zarah and Fort Scott, Kansas. Companies F and G were involved in the establishment of Fort Dodge in the summer of 1865. Their duties involved scouting, wagon train escort and operating against Indians. Members of the regiment were present as guards at the signing of the Little Arkansas Treaty. The regiment mustered out at Fort Leavenworth November 7, 1865.