Following the costly but tactically inconclusive Battle of Stones River (December 31, 1862 – January 2, 1863) between Rosecrans and Bragg at Murfreesboro, Tennessee, Bragg withdrew his army about 30 miles to the south, along the Duck River and behind the ridge known as the Highland Rim, which encircles the Nashville Basin. Small groups of pickets protected the passes through the Highland Rim and cavalry protected each flank, a front of almost 70 miles. Bragg, headquartered in Tullahoma, was concerned that Rosecrans would advance to seize the strategic city of Chattanooga, a vital rail junction and the gateway to northern Georgia. His cavalry was spread over such a wide front because he was also concerned at a tactical level that Rosecrans might be able to turn his position, forcing him to retreat or to fight at a disadvantage. Bragg assumed that any attack would be made against his left flank through the easy-to-cross Guy's Gap in the direction of Shelbyville, so he placed his larger infantry corps commanded by Lt. Gen. Leonidas Polk in strong entrenchments at Shelbyville. Eight miles to his right, the corps of Lt. Gen. William J. Hardee was fortified in Wartrace, protecting the main road to Chattanooga and positioned to reinforce the other three passes through the Highland Rim—(from west to east) Bell Buckle Gap, Liberty Gap, and Hoover's Gap. Hoover's Gap was almost undefended; it was a four-mile-long pass between the 1100-foot ridges separating the Stones and Duck Rivers. The pass was so narrow that two wagons could barely pass side by side and was commanded by the surrounding ridges. Strong entrenchments were constructed, but they were manned by only a single cavalry regiment. After the campaign, Bragg was criticized for the inadequate nature of his Tullahoma position. Hardee told him that it was subject to both frontal and flanking attacks.