Organized at Burlington, Iowa, July 17, 1861, moving to Keokuk on August 2d, and to St. Louis on the 19th. In October it participated in Fremont's Missouri campaign against Price, and during the winter of 1861-2, the regiment guarded the railroad from Sedalia to Tipton. In March, 1862, it moved to Pittsburg Landing, where it was assigned to Sherman's Division, Colonel McDowell being placed in command of the brigade. The battle of Shiloh occurred soon after, in which the regiment was commanded by Captain John Williams, its casualties in that battle amounting to 52 killed, 94 wounded, and 37 missing; a total of 183, out of less than 650 engaged. The Sixth continued in Sherman's Division during the Siege of Corinth, after which McDowell's Brigade moved to Memphis, remaining there several months. The regiment passed the winter of 1 862-3 at LaGrange, Tenn. Under command of Colonel Corse, the regiment distinguished itself on the skirmish line at Jackson, Miss., July 1 6, 1 863, its gallantry there eliciting a special complimentary order from General William S. Smith, the division commander. At Missionary Ridge, the regiment was in Ewing's Division, Fifteenth Corps; its loss there was 8 killed and 57 wounded. Colonel Corse received a serious wound in that battle, and soon after was promoted General for his gallant services. He afterwards made a national reputation by his gallant defense of Allatoona, where he received the historic dispatch signalled from Sherman, to "Hold the Fort, etc."