A marquisate in northwestern Italy, whose ruling family came to play a major role in the politics of the kingdom of Jerusalem and of Frankish Greece in the late twelfth and early thirteenth centuries.
The lands of Montferrat (mod. Monferrato, Italy) on the banks of the River Tanaro between Turin and Tortona were established as a marquisate around 1080 as a result of a partition of the lands of the Aleramid family. The marquises were generally allies of the Holy Roman Emperors against the increasingly powerful city of Lombardy. Marquis William V “the Old” (d. 1191), a kinsman of both Emperor Frederick I Barbarossa and King Louis VII of France, was a participant in the Second Crusade (1147-1149). His exalted connections were the main reason why his eldest son, William Longsword, was chosen as a husband for Sibyl, sister and heir to the leper king Baldwin IV of Jerusalem in 1176. However, Longsword died after a marriage of less than six months (June 1177), leaving a posthumous son, Baldwin V.
In the meantime the family’s political interests had turned against Frederick I. William the Old arranged a marriage between his youngest son, Ranier, and Maria the Porphyro- gennete, daughter of the Byzantine emperor Manuel I Komnenos, as part of a wide-ranging attempt by Byzantium to forge alliances involving Outremer and Western powers opposed to Frederick (1180). After Manuel’s death, Maria and Ranier, who had received the title Caesar, opposed the regency government installed for Maria’s half-brother, the young Alexios II. They eventually fell victim to a coup mounted by the usurper Andronikos Komnenos, who had them executed in 1183. In the same year the increasingly infirm Baldwin IV of Jerusalem had William Longsword’s son Baldwin V crowned as joint king. The young Baldwin succeeded as sole ruler on the death of the leper king in 1185, with Raymond III of Tripoli as regent.
William the Old came to the Holy Land in order to safeguard the interests of his grandson. He was given lands from the royal demesne and remained in the kingdom after the death of the young king (1186). William supported the new king, Sibyl’s second husband, Guy of Lusignan, and was taken prisoner by Saladin at the battle of Hattin (1187).
Shortly afterward William’s second son, Conrad, arrived at Tyre, after having spent several years in Byzantine service. He distinguished himself in directing the city’s resistance to Saladin and also secured his father’s release from captivity. Conrad’s success as a war leader during the efforts of the Third Crusade (1189-1192) to defend the kingdom of Jerusalem won him the support of those who were opposed to the continued rule of Guy of Lusignan after Sibyl’s death. With their encouragement Conrad married Isabella I, Sibyl’s half-sister (November 1190), and was eventually elected king. He was assassinated shortly after this settlement (1192). His daughter, known as Maria la Marquise, succeeded her mother on the throne of Jerusalem. Through Maria’s daughter Isabella II, who married Emperor Frederick II, the throne of Jerusalem passed from the Montferrat family to the Staufen dynasty.
Boniface I, the third son of William the Old, succeeded to the marquisate of Montferrat on the death of Conrad. As the chief leader of the Fourth Crusade (1202-1204), Boniface expected to be elected as Latin emperor of Constantinople after the crusade army overthrew the Byzantine emperor Alexios IV in 1204. When Baldwin of Flanders was elected instead, Boniface and his followers went off to conquer Thessalonica (mod. Thessaloniki, Greece) and central Greece. He married Margaret of Hungary, widow of the emperor Isaac II Komnenos, which brought him support from the Greek population. Boniface was killed in a Bulgarian ambush in 1207. He left his Greek lands to his young son by Margaret, Demetrius, who was recognized as king of Thessalonica by Emperor Henry in 1209. Demetrius’s kingdom was gradually overrun by the ruler of the Greek successor state of Epiros, Theodore Angelos Komnenos Doukas, and by 1222 he had fled to Italy to seek assistance. In 1224 Thessalonica itself fell to Theodore’s troops, and a crusade mounted by William VI of Montferrat (Boniface’s elder son) proved completely abortive.
Demetrius later assigned his claim over Thessalonica to Emperor Frederick II, who relinquished it in 1239. The descendants of William maintained their own claims until 1284, when the Byzantine emperor Andronikos II Palaiolo- gos married Irene, great-grandaughter of William VI. Their son, Theodore Palaiologos (1305-1338), thus became the founder of the second Montferrat dynasty.