After a victory at Chancellorsville in May 1863, Confederate General Robert E. Lee led the Army of Northern Virginia through Maryland into Pennsylvania while the Army of the Potomac marched north searching for him, and on July 1-3 the armies met at Gettysburg before the Confederates began retreating to Virginia three days later. On June 30, 1863, Confederate General J.E.B. Stuart’s 5,000-man cavalry corps prepared to move from Union Mills, Maryland, to Hanover, but at about 10 A.M. a detachment approaching the junction there unexpectedly encountered the rear guard of the Union cavalry corps under General H. Judson Kilpatrick. Stuart had left Lee’s army in northern Virginia to impede Federal forces, gather intelligence, acquire provisions, and disrupt rail and telegraph lines during a raid through Maryland into Pennsylvania, but by June 29 he had reached Union Mills dangerously out of touch with Lee. The capture of 125 Union wagons carrying provisions and 600 mules saddled with supplies slowed his progress and kept him far from Lee. At Hanover, sixty cavalrymen under Confederate Colonel John Chambliss ran into Union Lieutenant Henry Clay Potter’s forty-man rear guard, gunfire shattered the town’s morning calm, the first battle on free soil erupted there, and the Federals retreated up Frederick Street.