Principality of Achaea

Also known as Principality of Morea, Principatus Achaeae

The most successful and longest-lived of the Frankish states in mainland Greece — the Latin lordship of the Peloponnese (Morea), founded after the Fourth Crusade.

The Principality of Achaea was carved out of the Peloponnese by William of Champlitte and Geoffrey I of Villehardouin in 1205, in the chaotic aftermath of the Fourth Crusade and its dismemberment of the Byzantine Empire. The two knights had originally been sent south by Boniface of Montferrat, king of Thessalonica, to secure the southern flank; finding the Greek garrisons either weak or willing to negotiate, they conquered most of the peninsula in three campaigning seasons.

Under the Villehardouin dynasty (1205–1278), the principality became the most prosperous and culturally vivid of the Latin states in Greece. Its court at Andravida, and later at the spectacular hilltop palace of Mystras, drew visitors from across Latin Europe; the chivalric epic the Chronicle of the Morea preserves a vivid (if partisan) account of its history. Achaea was the dominant power in mainland Frankish Greece, holding overlordship at various times over the Duchy of Athens and the great Aegean lordships.

Decline set in after the loss of Mystras to the Byzantine Despotate of the Morea in 1262 and the Angevin takeover of the principality in 1278. By the late 14th century the Frankish baronage had been reduced to a few coastal strongholds, mostly in the Navarrese Company's hands, and in 1432 the Despotate of the Morea finally absorbed what remained. A small Frankish revival in 1453–54, in the chaos of the Ottoman conquest, was the last episode.

Read more on Wikipedia: English article