The Twenty-Ninth Infantry was mustered into the United States service at Camp Butler, Illinois, August 19, 1861, by Captain T. G. Pitcher, U.S.A., and was commanding by Col. James S. Reardon, and was assigned to the Brigade of Brigadier General John A. McClernand.

Early in September it was ordered to Cairo. In October, formed a part of an expedition, under command of Colonel R. J. Oglesby, to Bloomfield, Mo. In January 1862, expedition into Kentucky, under Brigadier General McClernand. February 1862, regiment was assigned to the Brigade of Colonel R. J. Oglesby, (Eighth, Eighteenth, Twenty-ninth, Thirtieth and Thirty-first Illinois,) and Division of Brigadier General McClernand. This command was the first to enter Fort Henry, after its evacuation.

In the battle of Fort Donelson, the Brigade formed the extreme right of the line of investment, meeting the enemy first and fighting them longer than any other portion of the army. Regiment lost 100 men, killed and wounded, of which 30 were killed on the field.

March 1, 1862, the Regiment was assigned to Colonel L. F. Ross' Brigade, composed of Seventeenth, Twenty-ninth, Forty-third and Forty-ninth Illinois Volunteers, and proceeded to Savannah, Tennessee. 20th March, proceeded to Pittsburg Landing. April 1st, Capt. E. M. Ferrell was promoted Lieutenant Colonel, vice Dunlap, resigned. The Regiment bore a most honorable part in the battle of Shiloh, April 6th and 7th, 1862. With an effective strength of 400 men, it lost 100 killed and wounded.

April 15, 1862, Major M. Brayman was promoted Colonel, vice Reardon, resigned. The Regiment was constantly engaged during the siege of Corinth, May 1862. June 6, assigned to Brigade of Colonel C. C. Marsh, composed of Eleventh, Twentieth, Twenty-ninth and Forty-fifth Illinois, and moved to Jackson, Tenn. July 1st, 1862, assigned to Brigade of Colonel M. K. Lawler, composed of Eighteenth, Twenty-ninth, Thirtieth and Thirty-first Illinois, and during the month made frequent incursions into West Tennessee.

October 1st, sent to reinforce General Rosecrans, at Corinth. Arriving too late for the battle, formed the advance of the pursuit to Ripley, Miss., and returned to Jackson.

September 25, Lieutenant Colonel C. M. Ferrill, promoted Colonel, vice M. Brayman, promoted Brigadier General. Adjutant Loren Kent, promoted Lieutenant Colonel.

December 1, Regiment proceeded to rear of General Grant's army, at Coldwater, Miss., and shortly afterwards went into camp at Holly Springs. 18th, Lieutenant Colonel Kent, with two companies (D and K) went to Jackson, Tenn., to protect that place.

December 20, Colonel R. C. Murphy, of the Eighth Wisconsin Volunteers, surrendered Holly Springs to the rebel General Van Dorn. Eight companies of the Regiment were paroled and sent to Benton Barracks. The camp and garrison equipage and books and records of the Twenty-ninth were destroyed. The eight paroled companies were kept at Benton Barracks until July 1863, when they were exchanged and returned to duty. The two remaining companies were assigned to the Western Navy, in February 1863, where they served with distinction during the siege of Vicksburg, losing one officer and several men in running the batteries at Vicksburg and Grand Gulf.

October 16, 1863, Lieutenant Colonel Kent was relieved, at his own request, as Provost Marshal General of the Army of the Tennessee, and assumed command of his regiment, which was assigned to General Logan's Division, of the Seventeenth Army Corps.

October 19, the One Hundred and Thirty-first Illinois Volunteers was consolidated with the Twenty-ninth, and Lieutenant Colonel Kent promoted Colonel, vice Colonel Ferrell, resigned.

December 1st, 1863, moved to Natchez, and remained on garrison duty.

In January 1864, the Regiment re-enlisted, and was mustered as veterans, and, July 19, received veteran furlough from Springfield, Ill.

Moved from Springfield, August 22, 1864; arrived at Natchez the last of the month, and remained until October, when moved to mouth of White river, having been assigned to Third Brigade, Reserve Corps, Military Division of West Mississippi. A short time afterward was ordered to Memphis, and thence to Paducah, arriving October 20, 1864, for protection of Kentucky from enemy's cavalry, which appeared on the border.

November 26, embarked for Memphis, camping in that city November 29. December 21, marched with expedition into the interior of Tennessee. Hard marching, cold weather and bad roads. Returned December 31. January 1, 1865, embarked for New Orleans. Camped above the city at Kenner, on the 5th. February 11th, assigned to Third Brigade, First Division, Thirteenth Army Corps, Colonel Kent commanding Brigade and Lieutenant Colonel J. A. Callicott commanding Regiment. Embarked for Mobile. Landed at Dauphin Island on 15th February. March 17, embarked for Fort Morgan, and, landing, bivouacked on the beach. During eight succeeding days, were toiling over almost impassable roads to Spanish Fort, arriving on the 26th. Took an active part in the siege. Moved to Fort Blakely, arriving April 2, and was engaged in the whole siege, supporting the charge made by our Second Brigade, on the 9th, which resulted in the capture of the entire rebel army. Regiment lost, during the campaign, 26 men, killed and wounded.

April 10, marched for Mobile. Arrived 12th, and remained in camp. June 26, embarked on steamship Scott, for Texas. Arrived off Galveston, July 1. The sea being quite rough, two or three days were required to disembark. Soon after ordered to Millican, Texas, on Texas Central railroad, arriving on the 9th.

July 26, Regimental headquarters moved to Hempstead-two companies remaining at Millican, two at Brenham, and one at Beaumont.

The Regiment being in Provisional Division, Department of Texas, Major General F. Steele commanding. The Regiment reported to Major General J. A. Mower, commanding Eastern District of Texas, until November 6, 1865, when it was mustered out of the United States service by Lieutenant B. W. Ladd, Ninety-eighth Ohio, and A.C.M.

Placed en route for the State, November 8, and arrived 26th, receiving final pay and discharge, November 28, 1865.