Battle of Antietam breaks out.
The Battle of Antietam was fought near the Antietam Creek in Sharpsburg, Maryland. Thought to be the deadliest single day of the American Civil War – at least 4000 soldiers on both sides died – the battle ended Confederate General Robert E. Lee incursion into the North. While there were no clear victors, many believed that the withdrawal of Confederate soldiers from the battlefield before the Union Army did meant that the Union had won the battle.