Chattanooga campaign

Battle context

The Chattanooga campaign resolved the strategic crisis created by the Union defeat at Chickamauga in September 1863. After that defeat, Confederate General Braxton Bragg's Army of Tennessee besieged the Army of the Cumberland by occupying commanding terrain around Chattanooga, placing Rosecrans's force in a precarious position. The Union response consolidated Western forces under Ulysses S. Grant as commander of the newly formed Division of the Mississippi, bringing with it reinforcements drawn from both Mississippi and the Eastern Theater. Grant's first command decision was to relieve Rosecrans and replace him with George Henry Thomas, stabilizing Union leadership at a critical moment. The campaign thus marked a turning point in Union command structure in the West, concentrating authority and resources under Grant and positioning Union forces to press further into the Confederate interior.