4. What effect did the Battle of Antietam have on the Union? The Confederate retreat gave Abraham Lincoln the opportunity he needed to issue the Emancipation Proclamation. O It ended the Civil War. O Maryland joined the Union. General McClellan was able to follow a retreating Lee and capture most of his soldiers.

4. What effect did the Battle of Antietam have on the Union? The Confederate retreat gave Abraham Lincoln the opportunity he needed to issue the Emancipation Proclamation. O It ended the Civil War. O Maryland joined the Union. General McClellan was able to follow a retreating Lee and capture most of his soldiers.