The decisive moment of the battle, and perhaps of the whole war, was in the afternoon of the third day, when Lee sent forward his choicest troops in a last effort to break the middle of the Union line. The center of the attacking force was Pickett's division, the flower of the Virginia infantry; but many other brigades took part in the assault, and the column, all told, numbered over fifteen thousand men. At the same time, the Confederates attacked the Union left to create a diversion. The attack was preceded by a terrific cannonade, Lee gathering one hundred and fifteen guns, and opening a fire on the center of the Union line. In response, Hunt, the Union chief of artillery, and Tyler, of the artillery reserves, gathered eighty guns on the crest of the gently sloping hill, where attack was threatened. For two hours, from one till three, the cannonade lasted, and the batteries on both sides suffered severely. In both the Union and Confederate lines caissons were blown up by the fire, riderless horses dashed hither and thither, the dead lay in heaps, and throngs of wounded streamed to the rear. Every man lay down and sought what cover he could. It was evident that the Confederate cannonade was but a prelude to a great infantry attack, and at three o'clock Hunt ordered the fire to stop, that the guns might cool, to be ready for the coming assault. The Confederates thought that they had silenced the hostile artillery, and for a few minutes their firing continued; then, suddenly, it ceased, and there was a lull.