Late in August, 1863, the Army of the Cumberland (US), Maj. Gen. Wm. B. Rosecrans, USA, crossed the Tennessee River near Bridgeport and threatened Chattanooga. On Sept. 7th, learning that Rosecrans was moving toward his rear in the direction of Rome (42 miles S), Gen. Braxton Bragg, CSA, withdrew his Army of Tennessee (CS) from Chattanooga to this vicinity, with headquarters in LaFayette, to meet the Union advance when it crossed Lookout Mountain.
Deciding that Bragg was retreating via Ringgold (21 miles NE) and Summerville (18 miles S), Rosecrans divided his army to pursue both columns and to strike at Bragg's flanks. Thomas' 14th Corps moved through Stevens' Gap into McLemore's Cove, west of LaFayette; McCook's 20th Corps toward Summerville; Crittenden's 21st Corps toward Ringgold. By the 12th, when Rosecrans realized his error, his flanks were widely separated, leaving Thomas alone in front of Bragg's whole army. Although a hasty reconcentration was begun, it was not completed until the night of September 17th.
In the meantime, an effort by Bragg to crush Thomas and Crittenden in turn failed for want of strong leadership. This failure forced Bragg to fight Rosecrans' reassembled army near West Chickamauga Creek (15 miles N) on the 19th and 20th. Although Bragg won the Battle of Chickamauga, it required two days of desperate fighting, during which his losses almost nullified his victory.