 Crossing the Potomac River on a pontoon bridge under cover of night, 1,300 Union cavalrymen quietly escaped, overwhelming or avoiding Confederate pickets assigned to cover the winding road north.While moving in pitch black darkness, Davis came across an artillery wagon train belonging to Confederate Maj. Gen. James Longstreet, and using his deep Mississippi-accented voice, ordered their unsuspecting commander to change direction and accept his unit as cavalry escort.As sunlight broke, the wagon drivers were startled to discover drawn pistols from their blue-clad escort, and as a result Davis's command not only escaped to Union lines at Greencastle, Pennsylvania, by morning September 15, but also captured Longstreet's forty-wagon reserve ordnance train with no losses.