Major General William S. Rosecrans's Army of the Cumberland maintained its field headquarters here from the morning of September 16 to 11 a.m. on September 19, 1863, with the 14th Army Corps under Major General George H. Thomas, the 20th Army Corps under Major General Alexander McDowell McCook, the 21st Army Corps under Major General Thomas L. Crittenden, the Reserve Corps under Major General Gordon Granger, and the Cavalry Corps under Brigader General Robert B. Mitchell. Rosecrans reached Thomas's headquarters at Stevens' Gap from Chattanooga on the night of September 10 and, convinced that General Bragg was concentrating north of LaFayette for battle, began the rapid concentration of his army via McLemore's Cove to interpose between Bragg and Chattanooga. Army headquarters were established at this point on the morning of the 16th, and the concentration was completed on the evening of the 17th by the arrival of McCook's Corps on Thomas's right at Steven's Gap. At daylight on the 19th Crittenden's Corps was in position at Lee and Gordon's Mill, while Thomas's Corps moved left through the night of the 18th via Crawfish Springs, reaching the LaFayette Road at Kelly's House at daylight on the 19th, except for Negley's Division, which was turned eastward from Crawfish Springs toward Glass' Mill on the Chickamauga and on the morning of the 19th encountered Helm's Brigade of Breckinridge's Division. McCook's Corps followed Thomas early on the 19th, with Johnson's Division going into action on Thomas's line about noon, Davis becoming engaged near Viniard's House about 2 p.m., and Sheridan about 4 p.m.; army headquarters were moved from this point to Widow Glenn's toward noon on the 19th.