Then Sherman brought up all available troops and prepared for a third and decisive attack; and the enemy did likewise to meet him. This attack was not in itself successful. But it turned the fortunes of the day. It gave Grant the opportunity for which he had been watching through all those anxious hours. Standing on Orchard Knob, he saw the Rebels massing against Sherman, and then, precisely at three o'clock, he signalled to his two storming columns to make the grand assault upon the works at the base of Missionary Ridge. Says the _Tribune_ correspondent from the field: "Hardly had the roar of the signal guns ceased, when the cracking of musketry commenced and vibrated up and down the line, which extended in an unbroken chain quite two miles. The artillery stationed along the crest of Missionary Ridge opened vigorously, raining down on our men a perfect shower of shot and shell. To their fire our artillery replied no less vigorously, and the attacking column moved forward to the music of more than a hundred guns. "The distance between the rifle-pits and our skirmishers was probably not to exceed three hundred yards. In less than ten minutes the Rebels began to leave and climb the abrupt slope of the hill, in desperate eagerness to take shelter in the main line--Hardee's Corps--on the top. Cheer on cheer now go up from the attacking columns, and a galling fire is poured into the fleeing Rebels. But not to escape, for so sudden was the advance that many prisoners were taken in the pits. Notwithstanding the order was to halt at the rifle pits, at the foot of the Ridge, in the eagerness of the pursuit it seemed to be forgotten, and the chase is kept up with eagerness. Seeing this, General Grant, contrary to his original intention, directs the supporting column at once to advance, and along the entire line black masses in regular columns move forward to the grand assault. In the centre, where Wood's Division is advancing, some of his men are already half way up the rugged steep. The elevation is almost three hundred feet. Glancing up and down the Ridge's slope you see a score of battle flags, some further advanced than others; one or two so far ahead of the supports, save a few impetuous spirits who seem determined to scale the height first, that the attempt seems mere hardihood. From the crest of the Ridge the Rebel artillery now belch forth more furiously than ever, and rain the iron hail on the masses below. And yet there is no wavering or sign of it. Cheer on cheer roll in waves up and down the advancing line. The right, the centre, the left now go forward in order, to the support of those who seem to have pushed too daringly to the assault, in the determination to be first to make the ascent where the foe was in force.