Number of casualties at the Battle of Antietam 1862

The Battle of Antietam (also known as the Battle of Sharpsburg) is the single bloodiest day in the United States' military history, with almost 23,000 total casualties, which included over 3,600 fatalities. The battle began at dawn on September 17, 1862, as General Robert E. Lee's Confederate army were attacked by Major General George B. McClellan near Antietam Creek, Maryland. While the Union had almost double the Confederacy's numbers, McClellan did not commit his full force, and did not capitalize and push his attack any time he broke Lee's defensive line. This meant that Lee's men were able to hold off the Union army until reinforcements arrived in the evening and drove the battered Union army back, thus ending the battle. Although some skirmishes took place during the day before and after the 17th, they pale in comparison to the violence and losses suffered on that day.