Expansion and crusade . William built it to complete the conquest of southeastern Morea in 1249, but he had to cede it to the Byzantines in 1261. William came to power in Achaea when the childless Geoffrey II died in the summer of 1246. By the time of William's ascension, the relationship between Epirus and Nicaea had grown tense. In December 1246, Nicaean troops attacked and captured Thessalonica. William took advantage of the two Greek powers' conflict to complete the conquest of the southeastern Morea. He laid siege to Monemvasia with the support of a Venetian fleet and other Frankish rulers, including
Guy I de la Roche,
Lord of Athens (who owed allegiance to William for the Moreot fiefs of
Argos and Nauplia), and
Angelo Sanudo,
Duke of the Archipelago. The defenders suffered because of famine, but they capitulated only in 1248, after William promised to respect their property and liberty. He rewarded the town's leaders with estates and exempted them from feudal obligations. William's conquest of Monemvasia forced the
Tzakones of nearby Mount
Parnon into submission. To secure his gains, William ordered the construction of new fortresses. First, in late 1248 and early 1249, he personally directed the construction of
Mistra near the Mount
Taygetus; then the castle of
Grand Magne was built on the
Laconian Gulf. A third castle,
Beaufort, was constructed on the
Messenian Gulf. These castles secured the Frankish control of the Mount Taygetus, forcing the local Slavic tribe of the
Melingoi to acknowledge William as their ruler in return for the confirmation of their liberty.
Hugh IV, Duke of Burgundy spent the winter of 1248–49 in Achaea. He was on the way to
Cyprus where the participants of
Louis IX of France's
crusade against Egypt were assembling. William decided to join the crusade and mustered 400 knights and armed a fleet of 24 ships before he left for Cyprus together with Hugh in May 1249. On the way, he sent 100 knights to
Rhodes, an island that the
Genoese had recently conquered from the Nicaeans, to strengthen its defence. From Cyprus, William accompanied Louis to Egypt and remained with him until the end of the abortive military campaign. As a reward, Louis granted him the right to
mint coins in the style of the French . William returned to Achaea in May 1250. During the following five peaceful years, Achaea was the dominant power of Frankish Greece as most of the lesser Frankish rulers acknowledged William as their overlord.
War of the Euboeote Succession Carintana dalle Carceri was one ruler of Negroponte, sharing
Oreus and the island's northern triarchy, or third, with
Grapella of Verona. When she died in 1255, William wanted to seize her lordship, but Grapella laid claim to her inheritance. As the triarchs owed allegiance to both Achaea and Venice, Grapella could cite a 1216 ruling by the Venetian , or governor, of Negroponte, that stated a co-ruler of a triarchy was entitled to re-unite it if his or her partner died without issue. The lords of the island's two other triarchies,
Guglielmo I da Verona and
Narzotto dalle Carceri, supported Grapella's claim. The Venetian chronicler
Marino Sanudo writes that the conflict developed into a war after William had Guglielmo and Narzotto imprisoned, because their wives convinced the Venetian
Paolo Gradenigo to intervene and he seized the island's capital,
Chalcis. If the two triarchs were indeed incarcerated, they were held in captivity only for some months. William appointed his nephew
Geoffrey of Briel to lead an army to Negroponte. The Achaean troops laid waste to the island and expelled the Venetians. The
Doge of Venice,
Reniero Zeno, made
Marco Gradenigo the new . Gradenigo gained the support of William's vassal,
William de la Roche and his brother, Guy I of Athens. Guglielmo of Verona and Narzotto dalle Carceri met Gradenigo at Guy's seat in
Thebes on 14 June 1256. At the meeting, the two triarchs rejected Achaean overlordship and swore fealty to Venice for their lordships. Two other Frankish lords,
Thomas II d'Autremencourt,
Lord of Salona and
Ubertino Pallavicini,
Marquess of Bodonitsa, joined the anti-Achaean coalition, while William secured the support of
Othon de Cicon, Lord of Karystos in Negroponte and the
Genoese. Gradenigo attacked Chalcis, and the Venetian infantrymen routed the Achaean cavalry near the city. The war quickly spread to mainland Greece. When William made preparations for an invasion of Attica, Geoffrey of Briel, who was the son-in-law of Guy of Athens, deserted him. Before long, Chalcis surrendered to the Venetians. William assembled his army and invaded Athens across the
Isthmus of Corinth in the spring of 1258. Guy I of Athens and his allies tried to stop the invasion at Mount Karydi, but William inflicted a decisive defeat on them in May 1258. Guy and his allies fled to Thebes, and William pillaged
Attica and
Boeotia. William attacked Thebes, but the
city's archbishop persuaded him to abandon the siege. Guy pledged he would never fight against William and agreed to accept the decision of the
High Court of Achaea for his disloyalty. After hearing Guy at
Nikli, the Achaean aristocrats sitting at the High Court decided they could not judge the case because Guy owed fealty to William only for his Moreot domains, not for the Lordship of Athens. Instead of forfeiting Guy's Moreot fiefs, the High Court referred his case for judgement to King Louis IX. As Guy accepted this ruling, peace was restored between the two Frankish rulers. Louis IX received Guy in Paris in June 1259. The King and the French barons decided Guy had done adequate penance for breaking his oath of fealty by undertaking the arduous journey to France.
Defeat and captivity Doge Ranieri Zeno ordered the new of Negroponte,
Andrea Barozzi, to conduct peace negotiations with William early in 1259, but he became embroiled in a new conflict between Epirus and Nicaea before the negotiations began. The Nicaean emperor,
Theodore II Laskaris, was succeeded by an underage son,
John IV Lascaris, in August 1258. An ambitious Nicaean aristocrat overthrew the child emperor's guardians and had himself crowned co-emperor as
Michael VIII Palaiologos. The ruler of Epirus,
Michael II Komnenos Doukas, wanted to take advantage of the Nicaean power struggles by fostering a wide anti-Nicaean coalition. He offered the hands of his daughters
Helena and
Anna to the
Hohenstaufen ruler of Sicily,
Manfred, and William respectively. He promised a generous dowry to William—80,000 , the castle of Liconia and nearby lands in southern Thessaly. Since their possession could strengthen his hold on Oreus, William quickly accepted the offer. He married Anna in Patras late in the summer of 1258. Before the end of the year, he and his father-in-law met in Patras and concluded a formal alliance. According to the
Chronicle of the Morea, Michael acknowledged William's claim to a revived Kingdom of Thessalonica. Michael VIII dispatched his brother,
John Palaiologos, with fresh troops to Thessalonica. He sent envoys to Epirus, Sicily and Achaea to start peace negotiations, but Michael II, Manfred and William refused. Enforced by newly hired mercenary troops, John Palaiologos launched a full-scale invasion of Epirus. Unable to resist alone, Michael II called for his allies' assistance in the spring of 1259. William assembled the bulk of the Achaean army. The Aragonese version of the
Chronicle of the Morea, in this respect a source of dubious reliability, estimates that "eight thousand first-class men-at-arms and twelve thousand men on foot" gathered for the campaign. William led the Achaean army across the
Gulf of Corinth and joined his father-in-law at
Arta. They marched to southern Thessaly, where reinforcements from Athens, Salona, Negroponte, Naxos and other Aegean islands joined them. After the Frankish and Epirote commanders decided to fight a pitched battle instead of attacking fortified towns, the allies marched to Macedonia as far as the plain of
Pelagonia to meet the enemy force in June 1259. Although the combined number of the Epirote–Frankish soldiery outnumbered the Nicaean troops, their command remained divided. John Palaiologos avoided battle, but his
Cuman and
Turkish archers continuously harassed the enemy camp. As their constant attacks exhausted the Franks and Epirotes, Michael II entered into negotiations with John Palaiologos's envoys, who urged him to desert his Frankish allies. The Byzantine historian,
George Pachymeres, asserts that the Epirote–Frankish coalition split after Achaean knights disrespected the beautiful
Vlach wife of Michael II's bastard son,
John Doukas, because William refused to discipline them. Outraged by William's rude remarks about his illegitimate birth, John Doukas deserted to the Nicaeans and convinced his father to abandon the campaign. John's unexpected attack from the rear caused panic and the Franks' retreat quickly turned into a flight. Historian
Kenneth Setton considers this whole episode, not reported by the more contemporary
Akropolites, doubtful. Akropolites credits the allies' defeat to Michael II's inability to resist the archers' attack. After his flight from the battlefield, the Epirotes either followed his suit or deserted to the Nicaean. As the Nicaean victory seemed inevitable, William fled towards
Kastoria. Akropolites writes that William hid under a haystack, but a soldier recognized him by his large protruding teeth. He was shackled and sent to Nicaea together with Anseau of Toucy, Geoffrey of Briel and other Achaean aristocrats. Michael VIII demanded the entire Achaean principality for William's release. William refused, stating that Achaea was "a land acquired by force of arms, held by
right of conquest" by the conquerors' descendants, and that he could not surrender his vassals' territory. During his prolonged but comfortable captivity, Guy I of Athens assumed the regency for him in Achaea. The Nicaeans failed to conquer Thessaly and Epirus after
their victory at Pelagonia, but their hold of Thessalonica was secured. As the Latin Empire was in ruins and exhausted, Michael VIII decided to re-conquer Constantinople from the Latins. He concluded an
alliance with Genoa to secure naval support for the siege, but his general,
Alexios Strategopoulos,
seized Constantinople without Genoese assistance, taking advantage of the absence of the Latin garrison on 25 July 1261. Michael VIII was again crowned emperor in the
Hagia Sophia and quickly deposed his underage co-emperor, John IV. After the fall of the Latin Empire, new negotiations began between Michael VIII and William about the conditions of William's release. They reached a compromise when William agreed to cede Mistra, Grand Magne and Monemvasia. As they had been built or conquered by William, their transfer did not violate Achaean customary law, but he could not cede frontier castles "without the counsel and consent of his liegemen". To legalize the transfer of the three castles, William's wife convoked the imprisoned Achaean lords' wives to a parliament. Although Guy I opposed the proposal, the "parliament of dames" consented to it because the Achaean ladies wanted their husbands back. Before releasing William, Michael VIII extracted an oath of fealty from him and took two Achaean ladies,
Margaret of Passavant and an unnamed sister of
John Chauderon, as hostages to secure William's compliance with their agreement. William returned to Achaea late in 1261. After the Byzantines had taken possession of the three castles, the Tzakones and the Melingoi transferred their loyalty to Michael VIII.
Conflicts with the Byzantines Neither William nor Michael VIII believed the peace treaty would be lasting: the Byzantines could use their Moreot bridgeheads for further expansion, while William could hardly acquiesce to the territorial losses. As a consequence of the Byzantine expansion in the Morea, William could rarely offer fiefs to western European knights, which diminished his principality's military power. Yet the Byzantines refrained from launching major invasions against Achaea because the Frankish cavalry were still able to inflict severe defeats on them. Instead, they attacked poorly garrisoned fortresses and seized them with the support of the local Greeks and Slavs.
Pope Urban IV released William from the oath he had taken at Constantinople under duress, and William started peace negotiations with the Venetians. In May 1262, William abandoned his claim to rule parts of Negroponte directly in return for the recognition of his suzerainty over the island. The Venetians were to destroy their seaside fort at Chalcis, but their quarter in the city was expanded. The possession of the port of Monemvasia allowed the Byzantines to transfer troops to the Morea. By the end of 1262, they seized
Cape Maleas and took control of the nearby
Mani Peninsula. Pope Urban IV urged the Catholic bishops and abbots of Frankish Greece to support the Achaeans against the "
schismatic" Byzantines on 27 April 1263, but he soon realized he could achieve his principal goal, the unity of Christendom, only through negotiating with Michael VIII. Michael VIII sent a new army to Monemvasia in the summer of 1263. The Byzantines invaded Arcadia and seized small fortresses, but the Franks
routed them near William's capital at
Andravida. Another Byzantine army marched towards
Kalavryta and seized it with the support of the local population. Next year, the Byzantine commander
John Kantakouzenos launched a new invasion of Arcadia, but he perished in a skirmish near Andravida. As he had failed to pay off his Turkish mercenaries, they entered into William's service. With their support, William defeated the Greeks at Nikli and laid siege to Mistra, but he could not capture it. In response to the Byzantine offensive in the Morea, Urban IV proclaimed a crusade against Michael VIII, but he also appointed new delegates to start negotiations with him about the
church union. Manfred of Sicily was willing to support the Franks against the Byzantines by force, but Pope Urban, who regarded Manfred as the principal enemy of the Papacy, rejected the offer. Instead of promoting an anti-Byzantine coalition, the papal delegates mediated a reconciliation between Michael VIII and William before the Pope died in October 1264.
Angevin suzerainty . The 1267
Treaty of Viterbo established
Charles I of Anjou's suzerainty over Achaea and his claim to succeed William in the principality. Urban's successor,
Pope Clement IV, granted the
Kingdom of Sicily to King Louis IX's ambitious younger brother,
Charles I of Anjou in 1265. Charles invaded southern Italy, and Manfred died fighting against the invaders in the
Battle of Benevento on 26 February 1266. Charles took full control of Manfred's kingdom and revived his plans for an anti-Byzantine coalition. As negotiations on the church union had not yielded results, Pope Clement embraced Charles' idea. He summoned Charles, the titular Latin Emperor Baldwin II and William to
Viterbo in Italy to discuss the conditions of an invasion of the Byzantine Empire by Charles. Charles and William reached an agreement after lengthy discussions. William swore fealty to Charles and promised not to "make
enfeoffment which will remain in effect after" his death "beyond 14,000 of land". He consented to the marriage of his daughter,
Isabella, with Charles's younger son,
Philip. Although his wife was pregnant, William acknowledged Charles and Charles's descendants as his heirs even if Isabella and Philip had no children and Anna gave birth to a son, only stipulating their son's right to hold one-fifth of Achaea in fief of the Angevins. As historian Peter Lock emphasizes, William's concessions show "the straits to which the principality had been reduced by the Greek offensive". In return, Charles promised military support to recover the territory lost to the Byzantines, but the details of his assistance remained unclarified. Baldwin II confirmed the
treaty and ceremoniously ratified in the presence of the Pope, 14 cardinals and further ecclesiastic and secular dignitaries in the papal chamber in Viterbo on 24 May 1267. In a separate treaty, Baldwin II ceded all his suzerain rights over Achaea to Charles and his successors in return for Charles' promise to assist him to recover Constantinople within six or seven years. As Charles's loyal vassal, William led 400 knights to fight against Charles's opponent, the young Hohenstaufen prince
Conradin in the
Battle of Tagliacozzo on 23 August 1268. On his return to Achaea in January 1269, William captured
Valona to establish a secure bridgehead for Charles's troops on the eastern shore of the
Adriatic Sea. The Achaean barons formally recognized the Treaty of Viterbo in the presence of Charles's envoys in 1270. Next year, Charles appointed the Marshal of Sicily,
Dreux of Beaumont, to represent him as captain general in Achaea. At the same time, the adventurer
Licario had seized a sturdy fortress near Karystos in Euboea. He made an alliance with the Byzantines, and with their support, he undertook to conquer the entire island. William and Dreux launched a joint military campaign against Licario and recaptured the fortress La Cuppa at Avlonari from him. The Byzantines launched two major invasions against Achaea between 1270 and 1275, but William was able to repel them with the support of Angevin troops.
Walter of Rosières, who held the
Barony of Akova in Achaea, died childless and his heir, Margaret of Passova was still held as hostage for William in Constantinople. William claimed the barony
escheated to the crown because she failed to claim it personally within the customary period of a year and a day. After her return from Constantinople, Margaret revived her claim to Akova and took the influential aristocrat
John of Saint Omer as her husband to secure his support. Saint Omer convinced William to compensate Margaret, and he restored one-third of the barony to her in 1276. As William's son-in-law Philip died childless early in 1277, it was evident that Charles or Charles's offspring would inherit Achaea from William on his death. He died on 1 May 1278. With his death, the male line of the Villehardouin family became extinct. Charles succeeded him without opposition, but he allegedly never visited Achaea.
Galeran of Ivry represented Charles in the principality as
bailli and vicar-general. ==Legacy==