"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? "To realize this, or any part of this state of things, it would be necessary to cross the river above Chattanooga with a heavy force, and assail the Rebels in their flank. To drive them from Missionary Ridge would be to render the work complete. If, in addition to these, Lookout Mountain should fall into our hands, little or nothing further could be desired." The topography of the place was also described by Mr. Brigham: "Missionary Ridge is a line of hills, ranging from 100 to 400 feet in height, sweeping round from Chattanooga Valley on our centre to our left, to less than one mile of the river above Chattanooga, and sloping westwardly toward the town, thus confronting our line of defenses at the point where the Ridge approaches the river, it backs up toward the east on a general line with, and from one to two miles from the river, toward which the hills have another sloping but rather abrupt face. On the westward slope Bragg planted his works; on the north or river slope he does not seem to have constructed permanent works. To cross the river and assail the Rebels on their flank, while General Thomas opened upon them in front, was the plan."