McClellan led efforts in the spring and early summer of 1861 to occupy the area of western Virginia that wanted to remain in the Union.
His forces defeated two small Confederate armies and paved the way for the region to later become the state of West Virginia.
On March 25, 1863, after the Senate refused to confirm Wright's promotion to major general, 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 named the Army of the Ohio, with himself in command.
Due to illness, Burnside asked to be relieved of command after the Battle of Fort Sanders and was replaced by Maj. Gen. John G. Foster on December 9.