The fort was the site of combat during The Battle of Fort Stevens on July 10–12, 1864. As anticipated by the military engineers, The Confederates attacked from the northwest, crossing the Potomac near Harper's Ferry and coming down the river valley. Lookouts at Fort Reno identified troop movements near Rockville. Commanders directed Fort Reno to fire its large artillery on the soldiers and the invading force shifted its assault 4 miles to the east across Rock Creek at Fort Stevens.