Triarchy of Negroponte The Triarchy of Negroponte was a crusader state established on the island of Euboea ( ) after the partition of the Byzantine Empire following the Fourth Crusade . Partitioned into three baronies ( " terzieri " , " thirds " ) run by a few interrelated Lombard families , the island soon fell under the influence of the Republic of Venice . From ca . 1390 , the island became a regular Venetian colony as the Kingdom of Negroponte ( " Regno di Negroponte " ) . History . Establishment . According to the division of Byzantine territory ( the " Partitio terrarum imperii Romaniae " ) , Euboea was awarded to Boniface of Montferrat , King of Thessalonica . Boniface in turn ceded the island as a fief to the Flemish noble Jacques d ' Avesnes , who fortified Chalkis . After his death in mid - 1205 however , the island was ceded to three Veronese barons : Ravano dalle Carceri , Giberto dalle Carceri and Pecoraro da Mercanuovo . They divided the island into three triarchies ( " terzieri " , " thirds " ) : the northern , based at Oreos ( ) , the southern , ruled from Karystos ( ) , and the central portion , ruled from Chalkis ( ) . The city of Chalkis or Negroponte ( " città de ' Lombardi " , " city of the Lombards " ) however was not under the latter ' s control , but served as overall capital of the island and joint residence of the Lombard rulers and their families . By 1209 however , Ravano had established himself as sole master of Euboea , styling himself as " dominus insulae Nigropontis " . Having allied himself with an unsuccessful Lombard rebellion against the Latin Emperor , Henry of Flanders , Ravano was eager to find a powerful protector . Thus , in March 1209 , he signed an alliance with Venice , which recognized Venetian overlordship and gave the Venetians significant commercial privileges . In May , however , in an act of political balancing , Ravano also acknowledged his vassalage to the Latin Empire . Succession disputes . However , already after the death of Ravano in 1216 , his heirs disagreed over the succession , allowing the Venetian bailli to intervene as a mediator . He partitioned the three baronies in two , creating thus six hexarchies ( " sestieri " ) . The northern triarchy of Oreos was divided between Ravano ' s nephews , Marino I and Rizzardo ; the southern triarchy of Karystos was divided between his widow , Isabella , and his daughter , Bertha ; and the central triarchy was divided between Giberto ' s heirs , Guglielmo I and Alberto . Provisions were also made that in the case someone among the " sestieri " died , his inheritor would be the other " sestiere " of the respective triarchy , and not his children . In fact , most " sestieri " were succeeded by their brothers , sons or nephews , keeping the baronies within the tight circle of the original Lombard families . In 1255 however , the death of Carintana dalle Carceri , hexarch of Oreos and wife to William II of Villehardouin , nominal overlord of Negroponte , led to the so - called " War of the Euboeote Succession " , which involved Achaea and Venice . William claimed for himself his wife ' s inheritance , while the Lombard barons were unwilling to concede it . On 14 June 1256 , Guglielmo of Verona and Narzotto dalle Carceri , the other two triarchs , repudiated their allegiance to William and pledged themselves to Venice . William responded by capturing Chalkis , which the Venetians retook in early 1258 . The war ended in the battle of Karydi in May / June 1258 , where William defeated the Duke of Athens , Guy I de la Roche , who had allied himself with the rebellious triarchs . Finally , in August 1259 , Doge Reniero Zeno negotiated a peace , followed by a treaty in 1262 , which recognized William ' s suzerainty over the island , but not his possession of the triarchy of Oreoi . Byzantine interlude . By that time , however , the Empire of Nicaea had established itself as the foremost power in the area of the former Byzantine Empire , reconquering several territories from the Latins . Its successes culminated in the recapture of Constantinople in 1261 and the reestablishment of the Byzantine Empire , whose energetic ruler , Michael VIII Palaeologus , sought to reconquer the remaining Latin principalities in southern Greece . To this end , he accepted the services of Licario , an Italian renegade , who had his base near Karystos . Under Licario ' s command , Byzantine troops soon conquered most of Euboea , except Chalkis . After the departure of Licario sometime after 1280 however , with Venetian aid , the island gradually returned to Latin control . By 1296 , Bonifazio da Verona had completely expelled the Byzantines from Euboea . Later history . In 1317 however , Karystos fell to the Catalan Don Alfonso Fadrique , vicar - general of the duchy of Athens and illegitimate son of Frederick III of Sicily . In 1319 , a peace treaty was signed between Venice and Don Alfonso , whereby he retained Karystos , which the Venetians acquired in 1365 . When the last triarchs , Niccolo III dalle Carceri and Giorgio III Ghisi , died in 1383 and 1390 respectively , they left their territories to Venice , which thus established complete predominance over the island . Nevertheless , the triarchic system was maintained , with Venetian families appointed to the positions of " terzieri " , while the Venetian podestà resided at Chalkis . Venice ' s rule lasted until 1470 , when , during the Ottoman – Venetian War of 1463 – 1479 , Sultan Mehmed II campaigned against Chalkis . With the fall of the city on 12 July , the whole island came under Ottoman control .