destroy Lee's army. On the night of September 13, the Army of the Potomac moved toward South Mountain, with Burnside's right wing of the army directed to Turner's Gap, and Franklin's left wing to Crampton's Gap. South Mountain is the name given to the continuation of the Blue Ridge Mountains after they enter Maryland. It is a natural obstacle that separates the Shenandoah Valley and Cumberland Valley from the eastern part of Maryland. Crossing the passes of South Mountain was the only way to reach Lee's army. Lee, seeing McClellan's uncharacteristic aggressive actions, and possibly learning through a Confederate sympathizer that his order had been compromised, quickly moved to concentrate his army. He chose not to abandon his invasion and return to Virginia yet, because Jackson had not completed the capture of Harpers Ferry. Instead, he chose to make a stand at Sharpsburg, Maryland. In the meantime, elements of the Army of Northern Virginia waited in defense of the passes of South Mountain. Battles of the Maryland campaign Harpers Ferry As Jackson's three columns approached Harpers Ferry, Col. Dixon S. Miles, Union commander of the garrison, insisted on keeping most of the troops near the town instead of taking up commanding positions on the surrounding heights. The South Carolinians under Brig. Gen. Joseph B. Kershaw encountered the slim defenses of the most important position, Maryland Heights, but only brief skirmishing ensued. Strong attacks by the brigades of Kershaw and William Barksdale on September 13 drove the mostly inexperienced Union troops from the heights. During the fighting on Maryland Heights, the other Confederate columns arrived and 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 and 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. Jackson took possession of Harpers Ferry and more