September 15 - The Union arsenal at Harpers Ferry, West Virginia, was captured by General Stonewall Jackson. A tremendous quantity of material was seized, and 12,500 men were captured. Harpers Ferry was abandoned and the captured troops set free by the Confederates on September 20 and reoccupied by the North on the 22nd.
Carruth, Gorton. "The Encyclopedia of American Facts and Dates". 10th Ed. New York: Harper Collins Publishers. ©1997.