George Crook graduated 38th out of a class of 43 from the United States Military Academy in 1852. He was commissioned in the 4th Infantry and was stationed in Northern California until the outbreak of the Civil War. On September 12, 1861, Crook was appointed colonel of the 36th Ohio, and was sent along with his regiment to western Virginia. On September 7, 1862, he was promoted to brigadier general, and commanded a brigade of regiments from Ohio during the battles of South Mountain and Antietam, both part of the Maryland Campaign. Following the campaign, Crook was placed in command of a cavalry division in the Army of the Cumberland under General George H. Thomas, and commanded the division through the Battle of Chickamauga. In the spring of 1864, Crook was sent back to western Virginia and took part in General Ulysses S. Grant’s spring campaign. During the campaign, Crook successfully commanded his brigade to a success against Confederate General A. G. Jenkins at the Battle of Cloyd’s Mountain. In August of 1864, Crook was given command of the Department of Western Virginia which would become the VIII Corps under General Philip Sheridan. Crook commanded his men throughout many of the battles of the Valley Campaign of 1864, including the battles of Third Winchester, Fisher’s Hill, and Cedar Creek. On October 21, 1864 Crook was promoted to major general, and returned to the command of his department in Cumberland, Maryland. On February 21, 1865 while located in Cumberland Maryland, General Crook along with General Benjamin F. Kelley were captured by a group of Confederate partisans under the command of Captain Jesse McNeill. On March 20, 1865, Crook was paroled and placed in charge of a division of cavalry in the Army of the Potomac. He commanded his division until the surrender at Appomattox Court House.