Command of the two hostile armies had undergone a considerable change during the siege period. Grant received orders to meet “an officer of the War Department” at Louisville, Ky. He proceeded by rail to Indianapolis, Ind., and just as his train left the depot there, en route to Louisville, it was stopped. A message informed Grant that Secretary of War Stanton was coming into the station and wished to see him. This was the “officer” from the War Department who gave Grant command of the newly organized Military Division of the Mississippi. Thomas replaced Rosecrans. McCook and Crittenden had previously been relieved of their commands and their corps consolidated into the Fourth Corps under command of Granger. Stanton accompanied Grant to Louisville and there the two spent a day reviewing the situation. In Bragg’s camp, Polk was relieved of his command, and Lt. Gen. William J. Hardee rejoined the army. Bragg’s army was reorganized into three corps commanded by Longstreet, Hardee, and Breckinridge. [Illustration: _Entrenchments of Thomas’ Corps, Army of the Cumberland in front of Chattanooga. Lookout Mountain in distance._ From _Battles and Leaders of the Civil War_.] When Grant reached Chattanooga on October 23 he found a plan already drawn up to open a new supply line for the besieged army. This plan of necessity was conditioned upon the terrain and the configuration of the river between Bridgeport, the railhead and base of supplies for the Union Army, and Chattanooga. (After the Tennessee River passes the city it flows southward for some 2 miles until it strikes Lookout Mountain where, after a short westerly course, it curves northward. This elongated loop of the river is called Moccasin Bend.) The plan called for 1,500 men on pontoons to float down the river from Chattanooga during the night of October 26-27 while another force marched across Moccasin Point to support the landings of the river-borne troops. Grant ordered the plan executed. The pontoon-borne troops quickly disembarked upon striking the west bank at Brown’s Ferry, drove off the Confederate pickets, and threw up breastworks. The troops marching across the neck of land came up to the east side of the ferry, joined this group, and constructed a pontoon bridge. Hooker’s advance from Bridgeport coincided with this action. He marched by the road along Raccoon Mountain into Lookout Valley. There he met the advance post of a Confederate brigade and drove it back. Maj. Gen. O. O. Howard’s Eleventh Corps moved to within 2 miles of Brown’s Ferry, while Brig. Gen. John W. Geary of the Twelfth Corps remained at Wauhatchie to guard the road to Kelley’s Ferry. The Confederates made a night attack against Geary which the latter repulsed, but both sides lost heavily. After this action, the short line of communication with Bridgeport by way of Brown’s and Kelley’s Ferries was held by Hooker without further trouble.