The 127th Illinois Infantry was organized at Camp Douglas in Chicago, Illinois, and mustered in for three years service on September 6, 1862, under the command of Colonel John Van Arman.

The regiment was attached to 4th Brigade, 5th Division, District of Memphis, XIII Corps, Department of the Tennessee, November 1862.

2nd Brigade, 2nd Division, XIII Corps, to December 1862.

2nd Brigade, 2nd Division, Sherman's Yazoo Expedition, to January 1863.

2nd Brigade, 2nd Division, XV Corps, Army of the Tennessee, to September 1863.

1st Brigade, 2nd Division, XV Corps, to June 1865.

Duty at Camp Douglas, Illinois, guarding prisoners, September 6 to November 9, 1862.

Sherman's Yazoo Expedition December 20, 1862 to January 3, 1863.

Assault and capture of Fort Hindman, Arkansas Post, January 10–11.

Moved to Young's Point, Louisiana, January 22, and duty there until March.

Steele's and Black Bayous and Deer Creek March 14–27.

Demonstrations on Haines' and Drumgould's Bluffs April 29-May 2.

Operations on Memphis & Charleston Railroad in Alabama October 20–29.

Operations on line of Pumpkin Vine Creek and battles about Dallas, New Hope Church, and Allatoona Hills May 25-June 5.