Antietam National Battlefield is located in Maryland and commemorates the Battle of Antietam, fought on September 17, 1862, during the American Civil War. This battle is known for being the bloodiest single-day battle in American history, with about 22,000 soldiers killed, wounded, or missing. The site features preserved landscapes, monuments, and historical markers that tell the story of the battle and its significance. Visitors to the battlefield can explore various trails, visit the Antietam National Cemetery, and learn about the events that took place through exhibits at the Visitor Center. The battlefield serves as a reminder of the sacrifices made during the war and the ongoing struggle for freedom and equality.