After being defeated in the Battle of Chickamauga, the Union Army of the Cumberland, commanded by Maj. Gen. William S. Rosecrans, withdrew into the city of Chattanooga, Tennessee, and was besieged by Gen. Braxton Bragg's Army of Tennessee. The Federals held a railhead at Bridgeport, Alabama, but because Bragg's army occupied Lookout Mountain, they had to bring supplies into the beleaguered city by wagon. The routes along the Tennessee River were easily harassed by the Confederates, so Rosecrans had to bring most of his supplies into Chattanooga from Bridgeport along a 60-mile wagon route across Walden's Ridge. Bragg ordered Wheeler to take the bulk of his cavalry corps and disrupt Rosecrans's communications across Walden's Ridge.