And to Rosecrans he telegraphed directly, bidding him be of good cheer, and adding:  “We shall do our utmost to assist you.”  To this end the administration took instant and energetic measures.  On the night of September 23, the President, General Halleck, several members of the cabinet, and leading army and railroad officials met in an improvised council at the War Department, and issued emergency orders under which two army corps from the Army of the Potomac, numbering twenty thousand men in all, with their arms and equipments ready for the field, the whole under command of General Hooker, were transported from their camps on the Rapidan by railway to Nashville and the Tennessee River in the next eight days.  Burnside, who had arrived at Knoxville early in September, was urged by repeated messages to join Rosecrans, and other reinforcements were already on the way from Memphis and Vicksburg.

All this help, however, was not instantly available.  Before it could arrive Rosecrans felt obliged to draw together within the fortifications of Chattanooga, while Bragg quickly closed about him, and, by practically blockading Rosecrans’s river communication, placed him in a state of siege.  In a few weeks the limited supplies brought the Union army face to face with famine.  It having become evident that Rosecrans was incapable of extricating it from its peril, he was relieved and the command given to Thomas, while the three western departments were consolidated under General Grant, and he was ordered personally to proceed to Chattanooga, which place he reached on October 22.

Before his arrival, General W.F.  Smith had devised and prepared an ingenious plan to regain control of river communication.  Under the orders of Grant, Smith successfully executed it, and full rations soon restored vigor and confidence to the Union troops.  The considerable reinforcements under Hooker and Sherman coming up, put the besieging enemy on the defensive, and active preparations were begun, which resulted in the famous battle and overwhelming Union victory of Chattanooga on November 23, 24, and 25, 1863.

The city of Chattanooga lies on the southeastern bank of the Tennessee River.  Back of the city, Chattanooga valley forms a level plain about two miles in width to Missionary Ridge, a narrow mountain range five hundred feet high, generally parallel to the course of the Tennessee, extending far to the southwest.  The Confederates had fortified the upper end of Missionary Ridge to a length of five to seven miles opposite the city, lining its long crest with about thirty guns, amply supported by infantry.  This formidable barrier was still further strengthened by two lines of rifle-pits, one at the base of Missionary Ridge next to the city, and another with advanced pickets still nearer Chattanooga Northward, the enemy strongly held the end of Missionary Ridge where the railroad tunnel passes through it; southward, they held the yet stronger point of Lookout Mountain, whose rocky base turns the course of the Tennessee River in a short bend to the north.