We left Company I at Taos, New Mexico, in 1861, under Captain Sibley. That officer went over to the Confederacy, leaving it in command of Lieutenant Walker. On October 9, 1861, it moved to Fort Garland, Colorado, where it remained until September, 1862.
During that month it joined forces with Company G at Camp Picket Wire, New Mexico, and started for Fort Leavenworth, Kansas, as an escort to General Canby, where it arrived October 27. The two companies soon proceeded to Washington, arriving there November 23, 1862. During October Companies L and M were authorized; their officers were assigned, and recruiting began at Carlisle Barracks, Pennsylvania. In December Company L, having received its recruits, went into camp at Fort Albany, Virginia. During this month Companies A, B, and D joined Company L at this place after also receiving recruits. Company M received its quota of recruits in February, 1863, and went into training at Washington, D.C. It joined the regiment at Warrenton Junction, Virginia, in May, 1863.
Company C was detached from the remainder of the regiment and was fighting in the West during the first two years of the war. It was moved from Holly Spring, Mississippi, and arrived at Memphis, Tennessee, January 15, 1863, where it acted for some time as escort to General Grant. During April, 1863, it was moved to Washington, D.C., and remained there until June, when it joined the regiment in the field. This company never received its quota of recruits as did the others, and during the rest of the war was considerably below them in strength. By June, 1863, the entire regiment of twelve companies, consisting of an aggregate of 832 officers and men, was assembled as a unit.