Founding of the Principality of Achaea

In 1205, following the Fourth Crusade, the French knights William of Champlitte and Geoffrey of Villehardouin conquered most of the Peloponnese, which the crusaders called the Morea. After defeating local Greek forces at the Battle of the Olive Grove of Kountouras, they established the Principality of Achaea, one of the most successful crusader states in Greece. William became its first prince, and Geoffrey and his descendants later took control. The principality was organized along feudal lines, with Frankish barons ruling over baronies from castles built across the Peloponnese, many of which still stand. Local Greek landowners kept much of their land and customs in return for loyalty. The principality reached its height under Prince William II of Villehardouin, who built the fortress of Mystras. Its court was famous across Europe for its chivalry. In 1259, however, William was captured by the Byzantines at the Battle of Pelagonia and had to hand over Mystras and other castles for his release. The principality gradually declined, and the Byzantines took its last territories in 1430.