Gen. William S. Rosecrans and the Army of the Cumberland had the Confederates in Tennessee on the run. A daring series of maneuvers severed the Rebels’ supply line and forced Braxton Bragg’s army to retreat from Chattanooga. “Old Rosy” led his men straight into a sudden counterattack on the banks of Chickamauga Creek on September 19.

Bragg had picked up reinforcements from Knoxville and from Mississippi and Virginia and was now ready to go on the offensive again. Rosecrans found his campaign in tatters. Casualties totaled thirty thousand in the course of the two-day battle.

Threatened with a rout, the Federals retreated to Chattanooga. Bragg and his troops closed in, and the Army of the Cumberland found itself facing the beginning of a bitter siege.