Which French emperor was defeated at the Battle of Waterloo?

Napoleon Bonaparte was defeated at Waterloo in June 1815, in what is now Belgium, ending the Hundred Days that followed his escape from exile on Elba. His plan was sound in principle: the Allied armies were separated, a British-led coalition force under Wellington and a Prussian army under Blucher, and he intended to beat each before they could join. He mauled the Prussians at Ligny but failed to destroy them, and the detachment sent to pursue them lost contact. At Waterloo, Wellington held a ridge through a day of costly French assaults, and the Prussians arrived on the French right in the afternoon, turning a hard-fought battle into a collapse. Napoleon abdicated days later and was exiled to Saint Helena in the South Atlantic, chosen for its remoteness, where he died. The victory shaped the European settlement that had been negotiated at the Congress of Vienna.

Napoleon's lasting legacy in France is less military than legal, in the civil code that still bears his name.