Although he was not aware of the urgency of the Confederate government with Johnston to induce him to take the initiative and operate by turning our left flank, Sherman had considered the possibility of this. The Fourth Corps had been concentrated at Cleveland on the East Tennessee and Georgia Railway about a dozen miles north of the Georgia state line and thirty-five miles from Dalton. The line of this railway was the easy road out of northern Georgia into Tennessee, and pretty closely followed the old Federal road. Had Johnston marched northward, he must have taken this route, and would have found his way barred by the Fourth Corps, which was strong enough to retard his advance till Sherman could have concentrated to meet him. The railways made a nearly equilateral triangle of the country between Cleveland, Chattanooga, and Dalton. It was thirty-eight miles from Chattanooga to Dalton, and twenty-seven to Cleveland. The east side of the triangle was near the Cooyehuttee Creek, a stream heading quite close to Cleveland and uniting, below Dalton, with the Connasauga. This valley is narrow west of the river, and is, much of the way, separated by a high and sharp ridge from the very broken country, which makes up the greater part of the triangle, where the branches of the Chickamauga run northward in parallel valleys till they unite near Chattanooga, and empty into the Tennessee. For nearly forty miles, therefore, the waters on the east side of the dividing ridge run southward to the Gulf of Mexico, whilst on the west side they run northward to the Ohio. Going south from Chattanooga, the railroad and the wagon roads have to thread their way from one valley to another, the latter climbing painfully the high ridges intervening, the former taking shorter cuts by deep excavations and tunnels. Within sight of Chattanooga the north end of Missionary Ridge is pierced for the railway where Grant's left wing fought in the battle which closed General Bragg's career as a commander in the field. Some twenty miles further on, another ridge is tunnelled where the railroad passes from the Chickamauga valley into that of Mill Creek, a small tributary of the Cooyehuttee, flowing eastward into that river in front of Dalton. Here, at Tunnel Hill, had been Johnston's advanced post during the winter, and Thomas's had been above Ringgold on the top of Taylor's ridge facing it on the west. But as Tunnel Hill did not extend many miles northward, and could be turned in that direction, the Confederates had made Dalton their intrenched camp, and were prepared to retire from Tunnel Hill whenever Sherman should advance in force. [Illustration: Map]