The town of Harpers Ferry, Virginia (now West Virginia), sits at the confluence of the Potomac and Shenandoah Rivers. It is surrounded by high cliffs on three sides making it nearly impossible to defend. Col. Dixon S. Miles, Union commander at Harpers Ferry, kept most the troops near the town instead of taking up commanding positions on the surrounding heights. Jackson put artillery on all the heights and bombarded the garrison. Miles decided to surrender the more than 12,000 men. As he debated with his officers over the decision, Miles was struck by a shell that shattered his left leg, a wound that proved fatal. Jackson then took possession of Harper’s Ferry before joining the rest of Lee’s army at Sharpsburg, He left General A.P. Hill’s division at the garrison to guard the prisoners.