The bloodiest day in American history took place on the 75th anniversary of the signing of the Constitution. On September 17, 1862, Robert E. Lee's Confederate Army of Northern Virginia fought George McClellan's Union Army of the Potomac outside Sharpsburg along Antietam Creek. That day, nearly 25,000 would become casualties, and Lee's army would barely survive fighting the much bigger Northern army. Although the battle was tactically a draw, it resulted...