In September 1863, Union Gen. William S. Rosecrans drives into Georgia flanking Confederate Gen. Braxton Bragg out of Chattanooga. Bragg, heavily reinforced, turns on Rosecrans and nearly traps him before he can fall back. The two great armies finally meet at Chickamauga. Through woods and small clearings, a confused but vicious battle rages as each army gropes and grapples at the other trying to find the enemy's flanks. At nightfall, Rosecrans holds his ground and continues to slide his army northward to Chattanooga. The following morning, however, Bragg launches an attack that catches Rosecrans in the midst of a clumsy readjustment of his lines. Half the Union Army is crushed and sent streaming back to Chattanooga. The other half, led by the redoubtable George H. Thomas, stands firm, weathers furious day-long assaults, and salvages honor and survival for the beaten Union Army.