Jackson defended the left (northern) flank, anchored on the Potomac, Longstreet the right (southern) flank, anchored on the Antietam, a line that was about 4 miles (6 km) long.
Jackson a apărat flancul stâng (nordic), ancorat pe Potomac, Longstreet pe cel drept (sudic), ancorat pe Antietam, o linie de aproximativ 6 km lungime.