Department of the Cumberland

Army of the Cumberland
Battle of Missionary Ridge
Active	October 24, 1862 – August 1, 1865
Country	United States
Branch	United States Army
Type	Field army
Engagements	American Civil War Battle of Stones River Tullahoma Campaign Battle of Chickamauga Chattanooga Campaign Atlanta Campaign Franklin–Nashville Campaign
Commanders
Notable commanders	William S. Rosecrans George H. Thomas

American Civil War

The Army of the Cumberland was one of the principal Union armies in the Western Theater during the American Civil War. It was originally known as the Army of the Ohio.

The origin of the Army of the Cumberland dates back to the creation of the Army of the Ohio in November 1861, under the command of Brig. Gen. Robert Anderson. The army fought under the name Army of the Ohio until Maj. Gen. William S. Rosecrans assumed command of the army and the Department of the Cumberland and changed the name of the combined entity to the Army of the Cumberland. When Rosecrans assumed command, the army and the XIV Corps were the same unit, divided into three "grand divisions" (wings) commanded by Alexander McCook (Right Wing), George H. Thomas (Center), and Thomas L. Crittenden (Left).

General Orders No. 168 was the order passed by the Union Army on October 24, 1862, that called for the commissioning the XIV Corps into the Army of the Cumberland.

The army's first significant combat under the Cumberland name was at the Battle of Stones River. After the battle the army and XIV Corps were separated. The former Center wing became XIV Corps, the Right wing became XX Corps, and the Left wing became XXI Corps. Rosecrans still retained command of the army. He next led it through the Tullahoma Campaign and at the Battle of Chickamauga, after which the army became besieged at Chattanooga. Maj. Gen. Ulysses S. Grant arrived at Chattanooga. Reinforcements from the Army of the Potomac and the Army of the Tennessee also arrived. Rosecrans had been a popular and respected commander, but because of his defeat at Chickamauga and inability to lift the Confederate siege, Grant chose to replace him with George H. Thomas on October 19, 1863.