Surprised by Thomas's move and realizing that his center and right might be more vulnerable than he had thought, Bragg quickly readjusted his strategy. Bragg assigned Col. Warren Grigsby's brigade of Kentucky cavalry to picket the Tennessee River northeast of Chattanooga and ordered Brig. Gen. Marcus Joseph Wright to bring his brigade of Tennessee infantry from Cleveland, Tennessee, by train to Chickamauga Station. He recalled all units he had recently ordered to Knoxville if they were within a day's march. Maj. Gen. Patrick Cleburne's division returned after dark from Chickamauga Station, interrupting the process of boarding the trains. Bragg began to reduce the strength on his left by withdrawing Maj. Gen. William H. T. Walker's division from the base of Lookout Mountain and placing them on the far right of Missionary Ridge, just south of Tunnel Hill. He assigned Lt. Gen. William J. Hardee to command his now critical right flank, turning over the left flank to Maj. Gen. Carter L. Stevenson. Bragg's concern for his right proved justified and his decisions were fortuitous. In the center, Maj. Gen. John C. Breckinridge ordered his men to begin fortifying the crest of Missionary Ridge, a task that Bragg had somehow neglected for weeks. Unable to decide whether to defend the base or the crest of the ridge, the divisions of Brig. Gens. William B. Bate and J. Patton Anderson were ordered to move half of their divisions to the crest, leaving the remainder in the rifle pits along the base. James L. McDonough wrote of the upper entrenchments, "Placed along the physical crest rather than what is termed the military crest ... these works severely handicapped the defenders."