On the night of September 13, the Army of the Potomac moved toward South Mountain, with Burnside's right wing of the army directed to Turner's Gap, and Franklin's left wing to Crampton's Gap.
Om natten den 13. september rykkede Army of the Potomac mod South Mountain med Burnsides højre fløj rettet mod Turner's Gap og Franklin's venstre fløj mod Crampton's Gap.