William II of Villehardouin

William of Villehardouin (Guillaume de Villehardouin; died 1 May 1278) was the last Villehardouin prince of Achaea (as William II) and ruled the principality at the height of its power and influence(1246 - 1278).

William was the son of Geoffrey I Villehardouin. In 1236 he aided the Latin Empire against the Byzantine Empire of Nicaea, and was rewarded with the overlordship of the Venetian Duchy of the Archipelago and other Venetian territories in the Aegean Sea. In 1239 he married the daughter of Narjot de Toucy and of Narjot's first wife (who was the daughter of the dowager empress Anna). William came to power in Achaea in 1246 when his brother Geoffrey II Villehardouin died.

As prince he conquered the remaining territory of the Peloponnese (known at the time as Morea) and built the fortress of Mistra near Sparta. In 1249 he captured Monemvasia with help from his Euboeote vassals, and later that year accompanied Louis IX of France on the Seventh Crusade, joining him in Cyprus with 400 knights and 28 ships. Louis also gave him a license to mint coins in the style of royal French money.

Under William's rule the Duchy of the Archipelago, the Duchy of Athens, and the Lombard lords ("triarchs") of Euboea recognized him as their lord. In 1255 his Venetian second wife Carintana dalle Carceri died, leading to a dispute over the inheritance of a fief in Euboea, and war broke out between Venice and Achaea (the War of the Euboeote Succession). William won the war and also defeated the Duke of Athens in 1258, reaffirming his influence over the duchy.

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