The Battle of Antietam was fought on September 17th, 1862. It was the worst day of the war, with almost 23,000 killed, wounded and missing. Of those, almost 4,000 were killed, making it the bloodiest single day in the Civil War and US history. How did that come happen? The two armies threw themselves at each other with reckless abandon, both sides looking for an advantage with attack and counterattack. Such a hectic battle can be confusing and difficult to understand. The Antietam Battlefield Atlas is the result of years of research and ground work. The 124 full color maps follow the course of the battle step-by-step during that fateful day. This Atlas is indispensable to the battlefield visitor as you walk the park and try to understand the movement of the troops and units who fought there.