Sherman now marched eastward, with all the men that could be spared, to join in the impending struggle at Chattanooga. There was no time to build bridges, so rivers were forded or crossed in scows. On November 15th he rode into Chattanooga, and soon thereafter all his troops were marshalled at that place, ready to deal with Bragg. Already Hooker's two corps had entered Lookout Valley, and the Army of the Cumberland was on the scene. Bragg had sent Longstreet to attack Burnside in Eastern Tennessee, and Grant was anxious lest Burnside should be overmatched. So, to prevent Bragg from sending more troops thither, and even, if possible, to force him to recall Longstreet, Grant determined upon an immediate attack by Sherman upon Missionary Ridge and Lookout Mountain.
The situation of the opposing forces, and the important issues at stake, were well described at the time by Mr. Brigham, in the _New York Tribune_:
"When General Bragg followed timidly the broken array of General Rosecrans on its retreat into Chattanooga, instead of pursuing that part which did not make its escape--(for not doing which he has been much blamed)--he halted the main body of his army on the morning of the 23d of September, on Missionary Ridge, immediately in front of our works, but mainly circling round from the left to the centre of our line, his right resting on the river about three miles above Chattanooga. The railroad to Cleveland--about twenty miles--connecting there with the main line from Knoxville to Atlanta, and the road to Dalton, some forty miles, connecting there with the same line, entered Chattanooga through Missionary Ridge, so that their terminus came to be near Bragg's headquarters, in sight of our works on the left. It was on the first named road that Longstreet's corps departed lately for East Tennessee, and over them Bragg has received most of his supplies, and maintained his connection, not only with East Tennessee, but with Georgia. The road to Knoxville once cut, or the connection even rendered precarious, it was plain that the situation of affairs in East Tennessee, especially with the rebels, would all at once become materially changed. Should the main line connecting East Tennessee and Georgia be broken, or seriously menaced, by driving the Rebels from Missionary Ridge, or by our gaining a foothold on the south side of the river on the flank of the Rebel position, the principal questions in the case would be, how would Longstreet get out of East Tennessee, and how far would Bragg be compelled to retreat?