Thomas remained loyal to the Union in 1861, and he was put in command of an independent force in eastern Kentucky. In 1862, Thomas achieved a Union victory at Mill Springs, thus undermining the entire western defense. Although, he arrived too late at Shiloh, after the battle, Thomas was put in command of the Army of the Tennessee. At the Battle of Perryville, his Fourteenth corps was not engaged. At Murfreesboro, his force held the center with his artillery In September 1863, Thomas organized Union defenses after the collapse of the Union right wing and withstood all afternoon long violent attacks on the left wing until he was allowed an orderly withdrawal of Union troops back to Chattanooga. For this perseverance, Thomas was called the "Rock of Chickamauga. " Thomas received command of the Army of the Cumberland in October 1863. His army play a large role in the victory at Chattanooga in November 1863. In November and December 1864, his victories at Franklin and Nashville, Tennessee, checked any Confederate advances. In pursuit of retreating Confederate forces, Thomas captured Selma, Alabama, and pursued to capture Jefferson Davis on 10 May 1865.