September 17, 1862, the day of the Battle of Antietam, was one of the most consequential days in the history of the United States and a moment in time when the future of the country could have veered in two starkly different directions. The fighting near Sharpsburg, Maryland would change the course of American history, but in the process, it became the costliest day this nation has ever known, with more than 23,000 men falling as casualties.
