Final answer:
The bloodiest single day battle in American history that gave Lincoln the "victory" he needed to announce the Emancipation Proclamation was the Battle of Antietam.
Step-by-step explanation:
The bloodiest single day battle in American history that gave Lincoln the "victory" he needed to announce the Emancipation Proclamation was the Battle of Antietam. This battle took place on September 17, 1862, near the town of Sharpsburg in Maryland. It was the first major battle of the Civil War to occur on Union soil and resulted in over 20,000 soldiers killed, wounded, or missing in just twelve hours.