The Confederate position was good. The terrain favored a defensive fight. To traverse the Cumberland Plateau the Union Army would have to move along roads that pierced the mountains by way of Hoover’s, Liberty, and Guy’s Gaps. The railroad to Chattanooga and another road passed through Bellbuckle Gap. This latter route and the road by way of Shelbyville were well fortified. Rosecrans resolved to make a feint toward Shelbyville with Granger’s Reserve Corps and most of the cavalry while the rest of his army moved toward the Confederate right. After stubborn fights at Hoover’s and Liberty Gaps the Confederates withdrew toward Tullahoma. So successful was Rosecrans’ flanking movement that Col. John T. Wilder’s mounted infantry brigade reached Decherd, on the main line of the Nashville and Chattanooga Railroad, and destroyed the depot and a few hundred yards of track. Although Wilder withdrew when superior Confederate forces appeared, his raid against the railroad was of great importance in forcing Bragg to evacuate Tullahoma. [Illustration: UNION ADVANCE MURFREESBORO TO CHATTANOOGA] Rough terrain and bad weather were the worst enemies of the Union Army. Brig. Gen. John Beatty records in his diary that “The road was exceedingly rough, and the rebels had made it impassable, for artillery, by rolling great rocks into it and felling trees across it.” He frequently mentions the rain which fell incessantly during the campaign. His entry of July 5 states that “Since we left Murfreesboro (June 24) rain has been falling almost constantly; today it has been coming down in torrents, and the low grounds around us are overflowed.” Yet, in spite of mountains and rain and the Confederate Army, Rosecrans, by this series of brilliant flanking maneuvers, forced Bragg to evacuate Tullahoma on July 1 and withdraw toward Chattanooga. _From Tullahoma to Chickamauga_ After the Tullahoma campaign, the two armies adopted their previous policy of remaining stationary. Each began to gather forces and equipment for a future struggle. The Union Army occupied a line from Winchester to McMinnville—the same territory the Confederates had occupied previously—while the Confederate General Bragg established his headquarters at Chattanooga. There the Army of Tennessee strengthened its defensive position and prepared to close the “gate” to further advances of the Army of the Cumberland. During July and August, Halleck again urged Rosecrans to move against Bragg’s forces, but Rosecrans failed to budge. In the latter’s judgment, three things were needed to insure a successful campaign. The first was ripe corn which would not be ready until August; the second was the repair of the railroad to the Tennessee River; and the third was support for his flanks. In spite of the constant flow of dispatches from Halleck to Rosecrans, it was not until August 16 that he began his movement southward to cross the river.