Following the Fourth Crusade, southern Greece had been divided among several Latin lordships, the most powerful of which was the Principality of Achaea, which controlled the entire Peloponnese peninsula. William II of Villehardouin, who in 1246 had succeeded his elder brother as prince, was a most energetic ruler, who aimed to expand and consolidate his rule over the other Latin states. Guy I de la Roche, the "Great Lord" of Athens and Thebes, was already his vassal for the fief of Argos and Nauplia, which lay in the Peloponnese, and William was also suzerain of the three Lombard baronies (terzieri, "thirds") of Negroponte (the medieval name of both the island of Euboea and its capital, modern Chalkis).