Napoleon abdicated in June, after his defeat at Waterloo. He lost the battle on 18 June 1815 and returned to Paris, where political support for his restored empire rapidly collapsed.
On 22 June, Napoleon formally abdicated for the second time, declaring that he was stepping down in favour of his young son, Napoleon II. The French legislature and a provisional government accepted the abdication, although Napoleon II never exercised real power.
A common mix-up is confusing this event with Napoleon’s first abdication, which occurred in April 1814 after the capture of Paris by the Sixth Coalition. The Waterloo defeat ended the Hundred Days, Napoleon’s brief return from exile on Elba. He later surrendered to the British and was sent to Saint Helena, where he died in 1821.