The 23rd Ohio Infantry Regiment was organized at Camp Chase (Columbus, Ohio) and mustered into duty on June 11, 1861, as a three-year regiment. Its 950 enlistees were originally led by Col. William Rosecrans. In July, after training and drilling, the regiment departed for western Virginia, where it served for several months, helping to restore that portion of Virginia to the Union. The 23rd was attached to Jacob D. Cox's Kanawha Brigade and served throughout much of the war in what became the IX Corps. The unit saw heavy action during the Battle of South Mountain, where Colonel Hayes was wounded in an attack on the slopes near Fox's Gap. Within a week, the regiment fought at Antietam in the fields southeast of Sharpsburg, Maryland, before returning to duty in West Virginia. It was again heavily engaged in Philip Sheridan's 1864 Valley Campaign. The regiment mustered out in July 1865.