Kat: I'm sorry but I can't be of much help. Harpers Ferry would make sense is it was Union, then Confederate, then Union again. This entire area shares that similarity so passes were probably used extensively in and around Harpers Ferry.

Harpers Ferry is kind of an interesting battle, for lack of a better word. Stonewall Jackson took a much smaller Confederate force and set cannons up on Maryland Heights (accross the Potomac River in Maryland)
and Loudoun Heights (accross the Shanandoah River in Virginia) and bluffed some 11,000 Union troops into thinking they were surrounded by a large Confederate force who surrendered Harpers Ferry to Jackson.
Sneaky, sneaky.

Ahhh, as fir re-enactments, they are big everywhere around this area, especially over in Northern Virginia.

Bobert