William of Villehardouin

William of Villehardouin, born in 1211, was a prominent figure in Frankish Greece, serving as the fourth prince of Achaea from 1246 to 1278. As the younger son of Prince Geoffrey I, he initially held the Barony of Kalamata during the reign of his elder brother Geoffrey II. When Geoffrey embarked on military campaigns against the Greeks of Nicaea, William took on the role of regent, showcasing his leadership abilities.

Upon the death of his childless brother in the summer of 1246, William ascended to power and swiftly capitalized on the conflicts between Nicaea and Epirus. Within three years, he successfully completed the conquest of the Morea, capturing Monemvasia and constructing three new fortresses. His military prowess forced the autonomous tribes of the Tzakones and Melingoi into submission, solidifying his control over the region.

In the early 1250s, William emerged as the most powerful ruler in Frankish Greece, with neighboring rulers acknowledging his suzerainty. His ambitions led him to claim the northern terziere of the Lordship of Negroponte on the island of Euboea in 1255. However, this claim was contested by his vassals, leading to a destructive war of succession supported by Venice and other Frankish rulers. After a decisive victory in Attica in May 1258, William's authority was reaffirmed, although he showed clemency towards his disloyal vassal Guy I de la Roche.

In 1259, a succession crisis in Nicaea prompted William to ally with Michael II Komnenos Doukas of Epirus and Manfred of Sicily against their common enemy. However, the coalition faced challenges in cooperation, leading to a significant defeat at the hands of the Nicaeans. Captured and imprisoned, William remained in captivity during the fall of the Latin Empire in July 1261. He was eventually released by the Byzantine emperor Michael VIII Palaiologos in exchange for three southern Morean fortresses, which facilitated further Byzantine expansion.

In a bid to secure his position, William sought external support and swore fealty to Charles I, the Angevin king of Sicily, in the Treaty of Viterbo on May twenty-fourth, 1267. This alliance allowed him to resist Byzantine invasions during the final years of his reign, marking a significant chapter in the history of Achaea.