Napoleon abdicated four days after the Battle of Waterloo. Waterloo was fought on 18 June 1815, and Napoleon formally gave up the throne on 22 June, ending his brief return to power during the Hundred Days.
After the defeat, Napoleon returned to Paris on 21 June hoping to rally political and military support. Instead, the Chamber of Representatives demanded that he step aside. Facing the threat of deposition and weakening public support, he abdicated in favour of his son, Napoleon II.
This was Napoleon’s second abdication. His first had followed the Allied capture of Paris in 1814, before his exile to Elba. The 1815 abdication did not immediately make his son an effective ruler: a provisional government soon took control, and Napoleon left France in July. He later surrendered to the British and was exiled to Saint Helena, where he died in 1821.