During the fighting on Maryland Heights, the other Confederate columns arrived. They were astonished to see that critical positions to the west and south of town were not defended. Jackson methodically positioned his artillery around Harpers Ferry and ordered Maj. Gen. A.P. Hill to move down the west bank of the Shenandoah River in preparation for a flank attack on the Federal left the next morning. By the morning of September 15, Jackson had positioned nearly 50 guns on Maryland Heights and at the base of Loudoun Heights. He began a fierce artillery barrage from all sides and ordered an infantry assault. Miles realized that the situation was hopeless. He agreed with his subordinates to raise the white flag of surrender. Before he could surrender personally, he was mortally wounded by an artillery shell and died the next day. After processing more than 12,000 Union prisoners, Jackson's men then rushed to Sharpsburg, Maryland, to rejoin Lee for the Battle of Antietam.