Army of the Ohio The Army of the Ohio was the name of two Union armies in the American Civil War . The first army became the Army of the Cumberland and the second army was created in 1863 . History . 1st Army of the Ohio . General Orders No . 97 appointed Maj . Gen . Don Carlos Buell to command the Department of the Ohio . All the forces of the department were then organized into the Army of the Ohio , with Buell in command . Early in 1862 , the army fought its first battle at Mill Springs , although only the 1st Division , commanded by Brig . Gen . George H . Thomas , was engaged . The whole army marched to reinforce Grant ' s Army of the Tennessee at the Battle of Shiloh . Buell was replaced as commander of the Department of the Ohio by Brig . Gen . Horatio G . Wright in August 1862 , but because of Wright ' s junior rank , Maj . Gen . Henry W . Halleck ordered Thomas to replace Wright in command . However , Thomas foresaw a major battle and felt it unwise to change an army commander on the eve of battle . Thus Buell remained in command of the Army and Thomas was made his second - in - command . The battle Thomas foresaw occurred in October 1862 , when the Army repulsed Gen . Braxton Bragg ' s invasion of Kentucky at the Battle of Perryville . Buell came under criticism for not following up his victory and was relieved of command of the Army , replaced by Maj . Gen . William S . Rosecrans . Rosecrans was also appointed to command of the Department of the Cumberland and subsequently renamed his forces the Army of the Cumberland . 2nd Army of the Ohio . On 25 March 1863 , Maj . Gen . Ambrose Burnside assumed command of the Department of the Ohio . Burnside consolidated all the forces of the department and created the XXIII Corps , which was also styled the " Army of the Ohio " , with himself in command . He became one of the few officers to directly command two completely different armies ( he had earlier commanded the Army of the Potomac ) . The new Army of the Ohio first repelled Morgan ' s Ohio raid , although the entire army rarely functioned as one complete unit during this campaign . Next Burnside moved to Knoxville , Tennessee . Here the IX Corps was added and the army grew to two corps , plus a division of cavalry . Burnside defeated the Confederates at the Battle of Fort Sanders in the Knoxville Campaign . After the battle , he asked to be relieved of command due to illness . Maj . Gen . John G . Foster replaced Burnside as commander of the Army and Department of the Ohio on December 9 . Foster ' s time in command of the Army was short . On February 9 , 1864 , Maj . Gen . John M . Schofield assumed command of the Department of the Ohio , and then the Army of the Ohio and the XXIII Corps in April . During this time the XXIII Corps and the Army of the Ohio were synonymous . Schofield led the Army during the Atlanta Campaign and pursued Confederate Lt . Gen . John Bell Hood into Tennessee after the fall of Atlanta . At the Battle of Franklin , Schofield inflicted a severe defeat on Hood ' s army before joining with Maj . Gen . George H . Thomas and the Army of the Cumberland for the Battle of Nashville . On February 9 , 1865 , Schofield was transferred to command the Department of North Carolina . When Schofield departed to assume departmental command , Maj . Gen . Jacob D . Cox temporarily assumed command of the Army . The XXIII Corps was ordered to North Carolina and only Cox ' s division was present for the Battle of Wilmington . It was not until March 1865 that the rest of the XXIII Corps landed at New Bern , North Carolina . Upon the arrival of the XXIII Corps in its entirety , Schofield joined that corps with the X Corps under Maj . Gen . Alfred H . Terry to form the Army of the Ohio . The Army was designated the Center Wing of Maj . Gen . William T . Sherman ' s army and participated in the final stages of the Carolinas Campaign . With the close of the war , the troops were mustered out of military service . A number of post - war reunions were held by various elements of the old Army of the Ohio .