The One Hundred and Forty-third Infantry Illinois Volunteers was organized at Mattoon, Ill., by Colonel Dudley C. Smith, and mustered in June 11, 1864, for 100 days.

On 16th June, moved for Memphis, Tenn., and, on 19th, was assigned to Fourth Brigade, District of Memphis, Colonel Buttrick commanding, and, on July 12, was assigned to Third Brigade, Colonel John Wood, One Hundred and Thirty-seventh Illinois, commanding. On July 27th, was ordered to report to Brigadier General Buford, commanding District of East Arkansas, at Helena, Ark. Arrived on the following day, and was assigned to garrison duty.

On 10th September, moved northward, and proceeded to Mattoon, Ill., where the Regiment was mustered out September 26, 1864.