The Ninth lost the most men, killed in action, of any Illinois regiment. After serving in the three months service, the regiment enlisted for three years, leaving Cairo September 5, 1861. It proceeded to Paducah, Ky., where it was stationed until February, 1862, when it moved with Grant's Army to Fort Donelson. It was then in McArthur's Brigade of C. F. Smith's Division; Its loss at Fort Donelson was 36 killed, 165 wounded, and 9 missing, total, 210. At Shiloh, the Ninth sustained the heaviest loss of any regiment in that battle; it fought there in W. H. Wallace's Division, encountering a severe fire, but holding its ground until ordered to retire, which it did in good order. The persistence with which it withstood the attack at Shiloh occasioned its unusual loss, its casualties amounting to 61 killed, 300 wounded, and 5 missing; a total of 366 out of 578 "present for duty," -- and the greatest loss in killed and wounded sustained by any infantry regiment during the war. At the battle of Corinth, Oct. 4, 1862, it lost 11 killed, 85 wounded, and 55 missing, out of 359 present in action, as officially reported by Colonel Mersy; many of the missing were killed. The regiment was then in Oglesby's (2d) Brigade, Davies's (2d) Division, Army of West Tennessee. In March, 1863, the regiment was changed to mounted infantry, and served as such with the Sixteenth Corps in 1863. In 1864, it was engaged on the Atlanta campaign. It was mustered out August 20, 1864, and the recruits remaining in the field were consolidated into a battalion of seven companies. This battalion was attached to the Seventeenth Corps, with which it marched on Sherman's famous campaign through Georgia and the Carolinas.