Antietam proved to be a major turning point in the war. It ended the Confederate invasion of the North, and with it the possibility of England and France recognizing an independent Confederacy. The Union victory also provided President Lincoln with the political opportunity to issue the Emancipation Proclamation.

Antietam was not only strategically important. It has the distinction of being the single bloodiest day not only in the Civil War but in all United States history. The Union army had over 12,300 dead, wounded or missing, and the Confederate Army over 10,300.