But the effect of this news upon Grant was very different from Bragg's expectations, for realizing that his adversary must have seriously weakened himself in sending the expedition against Burnside, he ordered Hooker, whose 16,000 men were already on hand, to make an immediate attack with a force drawn from various parts of the army, and on November 24, 1863, after a fierce engagement known as the battle of Lookout Mountain, the Union troops drove their opponents from one of the two important heights commanding Chattanooga.
In this success Sherman had effectively cooperated by attacking and holding the northern end of Missionary Ridge and Grant determined to follow up his advantage by moving the very next morning against this second and more formidable range of hills. Therefore, ordering Hooker to attack the Confederate right on Missionary Ridge and get in their rear at that point while Sherman assaulted their left, he held Thomas's troops lying in their trenches at the front awaiting a favorable opportunity to send them crashing through the center.
The main field of battle was plainly visible to the silent commander as he looked down upon it from a hill known as Orchard Knob, and he watched the effect of the attacks on both wings of the Confederate line with intense interest. Reënforcements were evidently being hurried to the Confederate right and left and Hooker, delayed by the destruction of a bridge, did not appear at the critical moment. Nevertheless, for some time Sherman continued to advance, but as Grant saw him making slower progress and noted the heavy massing of troops in his path, he ordered Thomas's waiting columns to attack the center and carry the breastworks at the foot of Missionary Ridge.
With a blare of bugles, 20,000 blue-coated men seemed to leap from the ground and 20,000 bayonets pointed at Missionary Ridge whose summits began to blaze forth shot and shell. Death met them at every stride but the charging troops covered the ground between them and the rifle pits they had been ordered to take in one wild rush and tore over them like an angry sea. Then, to the utter astonishment of all beholders, instead of halting, they continued charging up the face of Missionary Ridge, straight into the mouths of the murderous cannon.
"By whose order is this?" Grant demanded sternly.
"By their own, I fancy," answered Thomas.
Incredible as this suggestion seemed, it offered the only possible explanation of the scene. No officer would have dared to order troops to such certain destruction as apparently awaited them on the fire-crowned slopes of Missionary Ridge. Spellbound Grant followed the men as they crept further and further up the height, expecting every instant to see them hurled back as Pickett's heroes were at Gettysburg, when suddenly wave upon wave of blue broke over the crest, the Union flags fluttered all along the line and before this extraordinary charge the Confederates broke and fled in disorder.
Setting spur to his horse, Grant dashed across the hard-fought field and up the formidable ridge, issuing orders for securing all that had been gained. An opening wedge had now been inserted in Chattanooga's prison doors, and by midnight the silent captain had thrown his whole weight against them and they fell. Then calmly turning his attention to Burnside, he ordered him to hold his position at every hazard until he could come to the rescue and, setting part of his victorious veterans in motion toward Knoxville, soon relieved its garrison from all danger.
With the rescue of two Union armies to his credit Grant was generally regarded as the most fitting candidate for the chief command of the army, but by this time it was fully realized that the man who held that position would have to be invested with far greater powers than any Union general had thus far possessed. Halleck expressed himself as only too anxious to resign; Congress passed a law reviving the grade of lieutenant-general with powers which, up to that time, had never been entrusted to anyone save Washington, and responded to the cry, "Abraham Lincoln! Give us a MAN!" the President, on March 1st, 1864, nominated Ulysses Grant as Commander-in-Chief of all the armies of the United States.