 Despite being a tactical draw , Antietam is considered a turning point of the war and a victory for the Union because it ended Lee 's strategic campaign ( his first invasion of the North ) and it allowed President Lincoln to issue the Emancipation Proclamation on September 22 , taking effect on January 1 , 1863 . Although Lincoln had intended to issue the proclamation earlier , he was advised by his Cabinet to wait until a Union victory to avoid the perception that it was issued out of desperation . The Union victory and Lincoln 's proclamation played a considerable role in dissuading the governments of France and Britain from recognizing the Confederacy ; some suspected they were planning to do so in the aftermath of another Union defeat . McClellan had no prior knowledge that the plans for emancipation rested on his battle performance . 
