Which period of Napoleon's return from exile ended with the Battle of Waterloo?

The Hundred Days was the period of Napoleon’s return from exile that ended with the Battle of Waterloo. It began when he escaped Elba and returned to France in 1815, briefly reclaiming power from Louis XVIII.

Napoleon landed in southern France on 1 March and entered Paris on 20 March 1815, prompting Louis XVIII to flee. European powers meeting at the Congress of Vienna declared Napoleon an outlaw and formed the Seventh Coalition against him. He then tried to defeat the Allied armies before they could combine against France.

The Waterloo campaign included the battles of Ligny and Quatre Bras on 16 June, followed by Waterloo on 18 June. Napoleon’s defeat there ended his attempt to restore the French Empire. He abdicated for a second time on 22 June and was later sent to the remote island of Saint Helena.

The dates behind the name are not completely uniform. Some historians count from Napoleon’s landing to Waterloo, while the broader political definition runs from his return to Paris until the second restoration of Louis XVIII in July. Either way, Waterloo was the decisive military climax.