Still so lame that he could not walk without crutches, and had to be carried in arms over places where it was not safe to go on horseback, he left Louisville on the 21st of October, and reached Chattanooga on the evening of the 23d. Then began a work of masterly activity and preparation, in which his genius again asserted its supreme quality. Sherman with his army was ordered to join Grant. In five days the river road to Bridgeport was opened, the enemy being driven from the banks, two bridges were built, and Hooker's army added to his force. The enemy, having a much superior force, and assuming the surrender of the Army of the Cumberland to be only a question of time and famine, sent Longstreet with 15,000 men to reinforce the army of Johnston, holding Burnside in Knoxville, to the relief of whom the enemy supposed Sherman to be marching. Grant waited for Sherman, who was coming on between Longstreet and Bragg. All general orders for the battle were prepared in advance, except their dates. Sherman reached Chattanooga on the evening of the 15th, and with Grant inspected the field on the 16th. Sherman's army, holding the left, was to cross to the south side of the river and assail Missionary Ridge. Hooker, on the right, was to press through from Lookout valley into Chattanooga valley. Thomas, in the centre, was to press forward through the valley and strike the enemy's centre while his wings were thus fully engaged, or as soon as Hooker's support was available. The battle began on the afternoon of October 23. Orchard Knob, in the centre of the great amphitheatre, was attacked and captured, and became the Union headquarters. On the 24th Sherman crossed the river and established his army, on the north end of Missionary Ridge. On the morning of the same day Hooker assailed Lookout Mountain, and after a long climbing fight, lasting far into the night, secured his position; and the enemy, who had occupied the mountain, retreated across the valley at its upper end to Missionary Ridge. Grant's forces were now in touch from right to left. Everything so far had gone well.