The June 21st, 1863, battle saw Confederate Maj. Gen. J.E.B. Stuart and his cavalry division struggle to maintain a tenacious defense, holding Ashby’s Gap and later reinforcing it with earthworks, batteries from the army’s reserve and regiments of infantry. Two Confederate brigades of 3,000 men successfully fended off 5,800 Federals. The week’s battles allowed Confederate Gen. Robert E. Lee to cross the Potomac River into Maryland and continue his steady march northward. Union Commander Maj. Gen. Joseph Hooker, meanwhile, was disappointed that Brig. Gen. Alfred Pleasanton was not successful in uncovering Lee’s whereabouts. On June 28th, President Lincoln dismissed Maj. Gen. Hooker from command of the Army of the Potomac, and replaced him with George Gordon Meade.