Confederate Major General Thomas J. "Stonewall" Jackson arrived on Schoolhouse Ridge with 14,000 men to begin the Battle of Harpers Ferry, confronting the Union garrison, its strong position on Bolivar Heights, mountain obstacles, and the pressure of time. On the battle's second day, although Confederate bombardment had pummeled the Federals, they still held firm, so Jackson devised a three-point plan to force the issue. He ordered Major General A.P. Hill to march 3,500 men and 20 cannon under cover of night to a position behind the Federal lines to turn the Union flank, staged a fake attack one mile north against Bolivar Heights to distract the Federals from Hill's maneuver, and ordered 10 cannon moved from Schoolhouse Ridge across the Shenandoah River to a plateau on Loudoun Heights. By Monday morning, September 15, all was accomplished and the trap was set. In the three-day battle, Jackson used his knowledge of the area's rugged terrain, gained after beginning his Confederate service at Harpers Ferry as a colonel in April 1861 and returning 17 months later, to outmaneuver the Union troops and force the largest surrender of U.S. troops during the Civil War.