Resting with his troops in Frederick, Maryland, 20 miles northeast of here, Confederate General Robert E. Lee had hoped the Union garrison at Harpers Ferry would abandon its post when he invaded the North, but it did not. Lee decided to attack and divided his army into four columns, sending three to seize the three mountains overlooking Harpers Ferry. On the first day of the battle, the Confederates captured Loudoun Heights south of the Shenandoah River. North of the Potomac, Union forces abandoned Maryland Heights after a nine-hour defense. "Stonewall" Jackson seized Schoolhouse Ridge to the west, closing all doors of escape. Bolivar Heights remained in Union control, and the Confederates were poised to attack the surrounded garrison.