The One Hundred and Twenty-sixth Infantry Illinois Volunteers was organized at Alton, Ill., by Colonel Jonathan Richmond, and mustered in September 4, 1862.

Moved November 20, to Columbus, and thence to Bolivar, Tenn. On 28th, moved to Lagrange. On December 19, six companies marched to Jackson, Tenn., to reinforce that place, and, afterwards, moved to Humboldt, where they were joined by the remaining four companies, January 20, 1863. On 25th March, moved to Jackson, and was assigned to Second Brigade, Colonel James M. True commanding; Second Division, Brigadier General Nathan Kimball commanding; Sixteenth Army Corps, Major General Hurlbut commanding. Moved by rail to Memphis, and embarked for Vicksburg Landing, at Haines' Bluff, June 2.

Embarked for Helena, Ark., July 24. Marched with General Steele's Army, participating in the capture of Little Rock, September 10. Marched to Duvall's Bluff, October 24, 1863, and Colonel Richmond was assigned to the command of the post. On August 19, 1864, marched, via Little Rock, to Pine Bluff, Ark. February 12, 1865, moved to mouth of White River. Returned to Pine Bluff, June 4, and July 12, 1865, was mustered out.

The Regiment participated in the siege of Vicksburg. Six companies engaged in skirmish line, near Humboldt, Tenn., December 21, 1862, in capture of Little Rock, Ark., and in the fight at Clarendon, Ark., June 26, 1864.