Halleck, issuing orders from Washington, proceeded to disperse Grant's army hither and yon as he thought fractions of it to be needed. Grant wanted to move on Mobile from Lake Pontchartrain, but was not permitted to do it. Having gone to New Orleans in obedience to a necessity of conference with General Banks, he suffered a severe injury by the fall of a fractious horse, as he was returning from a review of Banks's army. For a long time he was unconscious. As soon as he could be moved he was taken on a bed to a steamer. For several days after reaching Vicksburg he was unable to leave his bed. Meantime he was repeatedly called upon to send reinforcements to Rosecrans, in Chattanooga, to which place the latter had retreated after the repulse of his army at Chickamauga, September 19 and 20. On October 3, Grant was directed to go to Cairo and report by telegraph to the Secretary of War as soon as he was able to take the field. He started on the same day, ill as he still was. On arriving in Cairo he was ordered to proceed to Louisville. He was met at Indianapolis by Secretary Stanton, whom he had never before seen, and they proceeded together.

On the train Secretary Stanton handed him two orders, telling him to take his choice of them. Both created the military division of the Mississippi, including all the territory between the Alleghanies and the Mississippi River, north of General Banks's department, and assigning command of it to Grant. One order left the commanders of the three departments, the Ohio, the Cumberland, and the Tennessee, as they were, the other relieved General Rosecrans, commanding the Army of the Cumberland, and assigned Gen. George H. Thomas to his place. General Grant accepted the latter. This consolidation was a late compliance with his earnest, unselfish counsel given before the Vicksburg campaign. Its wisdom had become apparent.

The centre of interest and anxiety now was Chattanooga, in East Tennessee, near the border of Georgia. The Confederates had been striving to retrieve the ground lost, since the fall of Fort Henry, by pushing northward in this direction. Halleck's dispersion of forces had sent Buell to this section, and Buell had been superseded by Rosecrans, a zealous and patriotic but unfortunate commander. The repulse at Chickamauga might have proved disastrous to his army but for the splendid behavior of the division under General Thomas, an officer not unlike Grant in the mould of his military talent, who there earned the sobriquet, "The Rock of Chickamauga."

The army of Rosecrans had been gathered again at Chattanooga, where it was confronted by Bragg, whose force surrounded it in an irregular semicircle from the Tennessee River to the river again, occupying Missionary Ridge on one flank and Lookout Mountain on the other, with its centre where these two ridges come nearly together. Chattanooga was in the valley between, near the centre of which, behind the town, was an elevation, Orchard Knob, held by the enemy. Bragg commanded the river and the railroads. The route for supplies was circuitous, inadequate, and insecure, over mountain roads that had become horrible. Horses and mules had perished by thousands. The soldiers were on half rations. Word came to Grant in Louisville, that Rosecrans was contemplating a retreat. He at once issued an order assuming his new command, notified Rosecrans that he was relieved, and instructed Thomas to hold the place at all hazards until he reached the front.

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.

Early on the next morning Sherman opened the attack. The ridge in his front was exceedingly favorable for defense, and during the whole night the enemy had been at work strengthening the position. Sherman's first assault failed, but he continued pressing the enemy with resolution, although making little progress. From Grant's place on Orchard Knob he watched the struggle. At three o'clock he saw Sherman's right repulsed. Then he gave to Thomas, standing at his side, the order to advance. Six guns were fired as a signal, and the Army of the Cumberland moved forward in splendid array to avenge Chickamauga. The immediate purpose was to carry the rebel rifle pits at the foot of the Ridge. This done, the soldiers were subjected to a galling fire from the line 800 feet above them. As by inspiration, they rushed on, climbing as they could, by aid of rocks and bushes, and using their guns as staves. They reached the crest and swept it in a mighty fury. It was the decisive action. All the columns now converged on the distracted foe who fled before them. Grant galloped to the front with all speed, urging on the pursuit and exposing himself to every hazard of the fight.

So Chattanooga was added to Grant's lengthening score of brilliant victories; and again, as at Donelson and at Vicksburg, he had been the instrument of relieving a tense oppression of anxiety that had settled upon the nation. Sherman, with two corps, was at once sent to the relief of Knoxville; but Longstreet, having heard of Bragg's defeat, made an unsuccessful assault and retreated into Virginia. By the administration in Washington, and by the people of the North, General Grant's preËminence was conceded. His star shone brightest of all. Congress voted a gold medal for him.