The camp remained active throughout the war as headquarters for the 18th U.S. Infantry, and served as a training base for fresh recruits needed to refill the ranks after significant combat losses at battles such as Stones River. (The 16th U.S. Infantry moved its base to Fort Ontario in New York.) For most of the war, Camp Thomas was under the jurisdiction of Brig. Gen. John S. Mason. A few volunteer regiments and artillery batteries, such as the 22nd Ohio Battery, also trained at Camp Thomas for various periods.