In order to understand the importance of the movements of both commanding generals, the geography of the country must be considered. When the Union commanders climbed to the top of the Lookout Mountain range and viewed the country, they began to have misgivings about their divided army. Thomas and McCook, 20 and 40 miles southwest of Chattanooga, respectively, found themselves on a mountain ribbed by ridges and hills, more than 1,000 feet above the valley floor. The few roads which ran over the mountain were narrow, rough, stony, and unusually steep. Thomas, looking to the east, saw Pigeon Mountain, a spur that juts off Lookout Mountain and veers in a northeastwardly direction. The acute angle of these diverging mountains forms McLemore’s Cove. Running into this cove from the northeast and ending there is the southern extremity of Missionary Ridge which begins immediately east of Chattanooga. Here, also, originates Chickamauga Creek which gave the ensuing battle its name. As the two Union corps moved eastward they found the country sparsely populated. There were a few farms, but most of the land was covered with cedar thickets and tangled undergrowth. The roads connecting farm and village were dry and dusty. The Union Army was now split into three distinct columns with its flanks more than 40 miles apart. In mountainous terrain, this made it impossible for them to support one another. In the period September 10-12, corps commanders began to receive reports that a large Confederate force was at LaFayette, Ga. It was Bragg’s army. He had not retreated as far south as Rosecrans had thought—he had stopped at LaFayette behind Pigeon Mountain. There he concentrated his army and awaited reinforcements. [Illustration: _Wooden railroad trestle at Cumberland Ravine, Ga., erected by Union Army to replace bridge destroyed by Confederates._ Courtesy National Archives.] _Reinforcements for General Bragg_ General Bragg had purposely given the impression that his army was disorganized and in full flight before Rosecrans. Actually, however, he was not running away but was quietly preparing for battle and gathering strength as reinforcements began to reach him. Realizing that Maj. Gen. Simon Bolivar Buckner’s Corps could not defend Knoxville from Burnside, and having no troops to spare for reinforcements, Bragg ordered Buckner to rejoin the Army of Tennessee. Buckner’s Corps of 8,000 men joined Bragg about the time the latter evacuated Chattanooga. Gen. Joseph E. Johnston from his army in Mississippi sent two divisions (about 9,000 men), under command of Major Generals John C. Breckinridge and W. H. T. Walker. A little later at Bragg’s insistence Johnston sent two brigades, under command of Brigadier Generals John Gregg and Evander McNair. These brigades added 2,500 more troops to Bragg’s Army. [Illustration: ROUTE OF REINFORCEMENTS _FOR_ GENERAL BRAGG _AT_ CHICKAMAUGA]