Emancipation Proclamation: After the Battle of Antietam, President Abraham Lincoln issued this proclamation which declared that all slaves in Confederate territory were to be set free.
American Civil War: The Battle of Antietam was one of the major battles fought during this war between the Northern states (Union) and Southern states (Confederacy).
Casualties: This term refers to people who are killed or injured during a battle or conflict. In the case of the Battle of Antietam, there were over 23,000 casualties.