Battle of Antietam

Robert E. Lee's first invasion of the North was halted along Antietam Creek near Sharpsburg, Maryland, where about 23,000 men were killed, wounded or missing in a single day, the bloodiest in American history. McClellan's Union army forced Lee back into Virginia. Lincoln used the result to issue the preliminary Emancipation Proclamation five days later, which helped keep Britain and France out of the war.