The Army of the Cumberland—the Union force—had undergone a reorganization since the Battle of Stones River. It now comprised three corps: The Fourteenth, Maj. Gen. George H. Thomas in command; the Twentieth, Maj. Gen. Alexander McD. McCook in command; and the Twenty-first, Maj. Gen. Thomas L. Crittenden in command. Maj. Gen. David S. Stanley commanded the Cavalry Corps. Maj. Gen. Gordon Granger commanded the Reserve Corps.

The left wing of General Bragg’s defense line was at Shelbyville under Lt. Gen. Leonidas Polk and its right wing at Wartrace and Fairfield under Lt. Gen. William Hardee—a line nearly 13 miles long. Two Confederate cavalry corps occupied positions on either flank—that on the right at McMinnville under Maj. Gen. Joseph Wheeler, the other on the left at Columbia under Brig. Gen. Nathan B. Forrest. The total strength of the Army of Tennessee was approximately 43,000 men at this time.

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.