In September 1862 the Confederate Army of Northern Virginia and the Union Army of the Potomac conducted one of the truly great campaigns of the Civil War. At South Mountain, Harpers Ferry, and Antietam, North and South clashed in engagements whose magnitude and importance would earn this campaign a distinguished place in American military history. The siege of Harpers Ferry produced the largest surrender of U.S. troops in the nation's history until World War II, while the day-long battle at Antietam on September 17 still holds the distinction of being the single bloodiest day of combat in Amer