The autumn months of 1863 witnessed in the Middle West a varying conflict ending in a Northern victory hardly less memorable than those of Gettysburg and Vicksburg. At last, after the fall of Vicksburg, Rosecrans in Middle Tennessee found himself ready to advance. By skilful manoeuvres, in the difficult country where the Tennessee River cuts the Cumberland mountains and the parallel ranges which run from north-east to south-west behind, he turned the flank of Bragg's position at Chattanooga and compelled him to evacuate that town in the beginning of September. Bragg, as he retreated, succeeded in getting false reports as to his movements and the condition of his army conveyed to Rosecrans, who accordingly followed him up in an incautious manner. By this time the bulk of the forces that had been used against Vicksburg should have been brought to support Rosecrans. Halleck, however, at first scattered them for purposes which he thought important in the West. After a while, however, one part of the army at Vicksburg was brought back to General Burnside in Ohio, from whom it had been borrowed. Burnside accomplished the very advance by Lexington, in Kentucky, over the mountains into Eastern Tennessee, which Lincoln had so long desired for the relief of the Unionists there, and he was able to hold his ground, defeating at Knoxville a little later an expedition under Longstreet which was sent to dislodge him. Other portions of the Western army were at last ordered to join Rosecrans, but did not reach him before he had met with disaster. For the Confederate authorities, eager to retrieve their losses, sent every available reinforcement to Bragg, and he was shortly able to turn back towards Chattanooga with over 71,000 men against the 57,000 with which Rosecrans, scattering his troops in false security, was pursuing him. The two armies came upon one another, without clear expectation, upon the Chicamauga Creek beyond the ridge which lies south-east of Chattanooga. The battle fought among the woods and hills by Chicamauga on September 19 and 20 surpassed any other in the war in the heaviness of the loss on each side. On the second day Bragg's manoeuvres broke Rosecrans' line, and only an extraordinarily gallant stand by Thomas with a part of the line, in successive positions of retreat, prevented Bragg from turning the hasty retirement of the remainder into a disastrous rout. As it was, Rosecrans made good his retreat to Chattanooga, but there he was in danger of being completely cut off. A corps was promptly detached from Meade in Virginia, placed under Hooker, and sent to relieve him. Rosecrans, who in a situation of real difficulty seems to have had no resourcefulness, was replaced in his command by Thomas. Grant was appointed to supreme command of all the forces in the West and ordered to Chattanooga. There, after many intricate operations on either side, a great battle was eventually fought on November 24 and 25, 1863. Grant had about 60,000 men; Bragg, who had detached Longstreet for his vain attack on Burnside, had only 33,000, but he had one steep and entrenched ridge behind another on which to stand. The fight was marked by notable incidents--Hooker's "battle above the clouds"; and the impulse by which apparently with no word of command, Thomas' corps, tired of waiting while Sherman advanced upon the one flank and Hooker upon the other, arose and carried a ridge which the enemy and Grant himself had regarded as impregnable. It ended in a rout of the Confederates, which was energetically followed up. Bragg's army was broken and driven right back into Georgia. To sum up the events of the year, the one serious invasion of the North by the South had failed, and the dominion on which the Confederacy had any real hold was now restricted to the Atlantic States, Alabama, and a part of the State of Mississippi.