ruins of Chapman's Mill, located north of Interstate 66 on Beverly Mill Drive. Sharpshooters used the mill's upper floor windows to defend the pass. Historic and wayside markers are placed along Virginia Route 55 just south of the mill. Notes References Hennessy, John J. Return to Bull Run: The Campaign and Battle of Second Manassas. New York: Simon & Schuster, 1993. . Salmon, John S. The Official Virginia Civil War Battlefield Guide. Mechanicsburg, PA: Stackpole Books, 2001. . National Park Service battle description CWSAC Report Update External links The Battle of Thoroughfare Gap: Maps, facts, photos, and preservation news (Civil War Trust) Thoroughfare Gap Thoroughfare Gap Thoroughfare Gap Thoroughfare Gap Thoroughfare Gap 1862 in the United States 1862 in Virginia Thoroughfare Gap August 1862 events