The regiment was organized by John A Logan in August of 1861 with 1130 men, recurited 700. , going to Camp Dunlap, near Jacksoncille, IL. From there it went to Cario, Il, where it was mustered into service on 18 Sep 1861
Their first action was seen at Belmont, MO on 07 Nov 1861. They were at Fort Henry on 07 Feb 1862, then on to Fort Donelson, TN were on 15 Feb 1862 the regiment lost 260 men. The group went by steamer to Shiloh, TN then on to Corinth, MS which the rebels had left by the time the got there. So the 31st went to Jackson, TN and remained in Western TN during the summer of 1862 near Forked Deer River, guarding the railroads In late summer they headed back to Corinth, following the rebels to Ripley, MS. They were involved in skirmishes at Chewalla, MS and Tuscumbia, MS, these ended 06 Oct 1862. The Regiment was in the first campaign by Gen Grant against Visksburg in the fall of 1862. The trrops move with Gen Grant to Lagrange, TN on 15 Jan 1863 before moving to Memphis. From there they went to Lake Providence, LA, arriving about 19 Mar 1863, from there the fighting lead them to Miliken's Bend, through Waynesboro and crossed the Mississippi River on 30 Apr 1863 below Grand Gulf. They met the rebels at Thompson's Hill on 01 May 1863 (near Port Gibson) The Regiemtn continued to fight through Ingram Heights on 03 May 1863, Raymond on 12 May 1863 and Jackson, MS on14 May 1863. The next day, they left for the march for Vicksburg. They came through a battle at Champion Hills on the 16 May 1863. They arrived in the Vicksburg, MS area 22 May 1863. The Regiment was involved in the operations including blowing up Fort Hill on 25 Jun 1863. They marched into Vicksburg on 04 Jul 1863. After the Battle at Vicksburg, they moved to Monroe, LA before making a winter camp at Black River, MS. In the spring of 1864, they traveled to Meridan, MS. The veterans of the regiment went on furlough until 19 Mar 1864, returning, the regiment camped at Clifton, TN. At Ackworth's Station, they joined Sherman's army. There were in shirmishes at Big Shanty and Brush Mountain. A battle at Kenesaw on 27 Jun 1864. The Army finally arrived at Atlanta, GA and the Regiment was involved in the Battles on 21, 22 and 28 Jul 1864. They left Atalnta and went through Lovejoy Stattion and Jonesborough. They were also with Sherman in his the pursuit of Gen Hood. They returned to Atlanta, GA about 13 Nov 1864, going with Sherman on his march to the sea.They reached Savannah, GA on 10 Dec 1864. They left GA on the Harvest Moon steamer to arrive in Beaufort, SC, were they remained from 05-13 Jan 1865. On 30 Jan 1865, They began a 54 day march through the Carolinas, through Salkahatchie, Columbia, Winsborough, Cheraw, Fayetteville, Bentonville finally to Goldsborough, NC on 24 Mar 1865. They arrive in Raliegh, NC on 14 Apr 1865.The Regiment finally arrived in Richmond, VA on 09 May 1865. They went to Washington DC on 24 May 1865, for the grand review, from there they moved to Louisville, KY, on 11 Jun 1865. On 19 Jul 1865, they regiment was mustered out of service by Lt August P Noyes. It was also mustered out at Springfield, IL on 23 Jul 1865 with 25 officers and 677 enlisted
With Sherman they had marched 2076 miles, under Grant 2000 miles. The regiment was in 14 battles and 25 skirmishes.
Co A--org in Pinkneyville, Perry Co by Capt John D Reece
Co B--org at Harrisburg, Saline Co by Capt Thomas J Crain
Co C--org at Marion, Wmson Co by Capt WA Fooney
Co D--org in Massac Co by Capt James H Williamson
Co E--org in Union Co by Capt Irvin C Batson
Co F--org by Capt John W Rigby of Caledonia, Pulaski Co
Co G--org by Capt Willis A Stricklin of Harrisburg, Saline Co
Co H--org by Capt Oramus Greenlee of Cario, Alexander Co
Co I--formed by Capt Edwin S McCook of Pekin
Co K--org by Capt Alexander S Somerville of Centralia