The Importance of the Battle of Antietam

The Battle of Antietam on Sept. 17, 1862, remains the deadliest one-day battle in American military history with nearly 23,000 casualties, including over 3,600 deaths. While the monument observing the “High Water Mark of the Rebellion” stands at Gettysburg, Pennsylvania, the true high tide of the Confederacy arguably came on a late summer day at Sharpsburg, Maryland, beside the swiftly flowing Antietam Creek. The U.S. Army’s victory there provided an opportunity to recast the American Civil War beyond just preserving the Union to one of emancipation — and eventually abolition of slavery. Although the war would drag on for almost another three years, the Confederacy would face increasingly long strategic odds after the defeat at Antietam.