The Principality of Achaea or Principality of Morea was one of the vassal states of the Latin Empire, which replaced the Byzantine Empire after the capture of Constantinople during the Fourth Crusade. It became a vassal of the Kingdom of Thessalonica, along with the Duchy of Athens, until Thessalonica was captured by Theodore, the despot of Epirus, in 1224. After this, Achaea became the dominant power in Greece, lasting continuously for 227 years and cumulatively for 229.
William of Villehardouin was the fourth prince of Achaea in Frankish Greece, from 1246 to 1278. The younger son of Prince Geoffrey I, he held the Barony of Kalamata in fief during the reign of his elder brother Geoffrey II. William ruled Achaea as regent for his brother during Geoffrey's military campaigns against the Greeks of Nicaea, who were the principal enemies of his overlord, the Latin Emperor of Constantinople Baldwin II. William succeeded his childless brother in the summer of 1246. Conflicts between Nicaea and Epirus enabled him to complete the conquest of the Morea in about three years. He captured Monemvasia and built three new fortresses, forcing two previously autonomous tribes, the Tzakones and Melingoi, into submission. He participated in the unsuccessful Egyptian crusade of Louis IX of France, who rewarded him with the right to issue currency in the style of French royal coins.
The Prince of Achaea was the ruler of the Principality of Achaea, one of the crusader states founded in Greece in the aftermath of the Fourth Crusade (1202–1204). The principality witnessed various overlords during its more than two centuries of existence, initially, Achaea was a vassal state of the Kingdom of Thessalonica under Boniface I of house Montferrat, then of the Latin Empire of Constantinople under the houses of Flanders-Courtenay, which had supplanted the Byzantine Empire, and later of the Angevin Kingdom of Naples. During the Angevin period, the princes were often absent, represented in the Principality by their baillis, who governed in their name. After 1404 the principality became sovereign as the Genoese Centurione II Zaccaria bought from the Neapolitan crown the princely rights.
Michael I Komnenos Doukas, Latinized as Comnenus Ducas, and in modern sources often recorded as Michael I Angelos, a name he never used, was the founder and first ruler of the Despotate of Epirus from c. 1205 until his assassination in 1214/15.
Philip I, known as Philip of Savoy was the lord of Piedmont from 1282 until his death and prince of Achaea between 1301 and 1307. He was the son of Thomas III of Piedmont and Guyonne de Châlon.
Isabella of Villehardouin was reigning Princess of Achaea from 1289 to 1307. She was the elder daughter of Prince William II of Achaea and of his third wife, Anna Komnene Doukaina, the second daughter of Michael II Komnenos Doukas, the despot of Epiros.
Guy II de la Roche, also known as Guyot or Guidotto, was the Duke of Athens from 1287, the last duke of his family. He succeeded as a minor on the death of his father, William I, at a time when the duchy of Athens had exceeded the Principality of Achaea in wealth, power, and importance.
Nicholas III of Saint-Omer was one of the most powerful and influential lords of Frankish Greece. He was hereditary Marshal of the Principality of Achaea, lord of one third of Akova and of one half of Thebes. He also served on three occasions as bailli of the Principality of Achaea.
Nicholas II of Saint Omer was the lord of half of Thebes in Frankish Greece from 1258 to his death in 1294. From his two marriages he became one of the richest and most powerful barons of his time, building a splendid castle at Thebes as well as the Old Navarino castle. He also served as bailli of the Principality of Achaea on behalf of the Angevins of Naples between 1287 and 1289.
Matilda of Hainaut, also known as Maud and Mahaut, was Princess of Achaea from 1316 to 1321. She was the only child of Isabella of Villehardouin and Florent of Hainaut, co-rulers of Achaea 1289–1297. After Florent's death in 1297, Isabella continued to rule alone until she remarried to Philip of Savoy in 1300. Per arrangements made with King Charles II of Naples, Isabella was not allowed to marry without his consent and after Philip failed to adequately participate in the king's campaigns against Epirus, Charles in 1307 revoked their rights to Achaea. Matilda, just fourteen years old, tried to press her claim as their heir but was refused by the bailiff Nicholas III of Saint Omer, who instead chose to wait for orders from Naples. Shortly thereafter, Charles appointed his favorite son, Philip of Taranto as the new Prince of Achaea.
The War of the Euboeote Succession was fought in 1256–1258 between the Prince of Achaea, William of Villehardouin, and a broad coalition of other rulers from throughout Frankish Greece who felt threatened by William's aspirations. The war was sparked by Villehardouin's intervention in a succession dispute over the northern third of the island of Euboea, which was resisted by the local Lombard barons with the aid of the Republic of Venice. The Lord of Athens and Thebes, Guy I de la Roche, also entered the war against William, along with other barons of Central Greece. Their defeat at the Battle of Karydi in May/June 1258 effectively brought the war to an end in an Achaean victory, although a definite peace treaty was not concluded until 1262.
The Lordship of Salona, after 1318 the County of Salona, was a Crusader state established after the Fourth Crusade (1204) in Central Greece, around the town of Salona.
The Barony of Karytaina or of Skorta was a medieval Frankish fiefdom of the Principality of Achaea, located in the Peloponnese peninsula in Greece, centred on the town of Karytaina in the mountainous region known as Skorta.
The Barony of Arcadia was a medieval Frankish fiefdom of the Principality of Achaea, located on the western coast of the Peloponnese peninsula in Greece, and centred on the town of Arcadia, ancient and modern Kyparissia.
Geoffrey of Briel, in older literature Geoffrey of Bruyères, was a French knight and the third lord of the Barony of Karytaina in the Principality of Achaea, in Frankish Greece. He led a colourful and turbulent life, narrated in detail in the Chronicle of the Morea. Accounted the finest knight in the Principality, he fought in the wars against the Byzantine Greeks, was captured in the Battle of Pelagonia in 1259, and was sent back to Achaea bearing the Byzantine terms in 1261. Geoffrey was twice deprived of his barony, once for rebelling against his uncle, the Prince of Achaea William II of Villehardouin, and then for abandoning the Principality without leave in order to spend time with a mistress, the wife of one of his feudatories, in Italy. He was pardoned both times, but henceforth held his title as a gift of the Prince. He died childless in 1275, and the Barony of Karytaina was split up.
Anna Komnene Doukaina, known in French as Agnes, was princess-consort of the Principality of Achaea in 1258–1278 and regent between 1259–1262, during the captivity of her husband, Prince William II of Villehardouin, by the Byzantine emperor Michael VIII Palaiologos. After William II's death in 1278, she re-married to the powerful baron Nicholas II of Saint Omer.
William d'Autremencourt was a Lord of Salona from 1258 to 1294.
Hugh of Briel, in older literature Hugh of Bruyères, was a French knight and the second lord of the Barony of Karytaina in the Principality of Achaea, in Frankish Greece.
Renaud of Briel, in older literature Renaud of Bruyères, was a French knight and the first lord of the Barony of Karytaina in the Principality of Achaea, in Frankish Greece.
The Second Parliament of Ravennika was convened in May 1210 by Latin Emperor Henry of Flanders in the town of Ravennika in Central Greece in order to resolve the differences between the princes of Frankish Greece and the Roman Catholic clergy of their domains.
