William VII (c. 1240 – 6 February 1292), called the Great Marquis (), was the twelfth Marquis of Montferrat from 1253 to his death. He was also the titular King of Thessalonica. Biography Youth William was born in Trino, the eldest son of Boniface II and Margaret of Savoy. He was named his father's heir in a testament of 1253, the year of his father's death and his succession. He remained under his mother's regency until 1257. Upon attaining his majority, he married Isabella, daughter of Richard de Clare, 6th Earl of Hertford, by second wife Maud de Lacy, in 1258. William's mother was a first cousin of Eleanor of Provence, queen consort of England, and it was through the latter's influence that the marriage was arranged. Marriage and issue William married Isabelle de Clare, daughter of Richard de Clare, 6th Earl of Gloucester. They had: daughter Margaret, married Infante John Following Isabelle's death in 1271, William married Beatrice, daughter of Alfonso X of Castile and Violant of Aragon. a son (1272–1273), died young a son (1272–1273), died young and twin of previous Yolande (1274–1317), married Andronikos II Palaiologos and had issue John I (c. 1275–1305), succeeded his father as Marquis Alessina (died before 1305), married Poncello Orsini Piedmontese politics In his first years, William looked to exert his power in the southern Piedmont, as many of his predecessors had tried, fighting the independence of the communes of Alessandria and Asti. William sought alliance and support from the Kingdom of France and the Roman Catholic Church. However, his relationship and proximity to the Holy Roman Emperor left him at odds with the Ghibellines. His anti-imperial, pro-French, Guelph policy left him not insignificant problems concerning the imperial authority and his imperialist neighbours. His participation in Guelph politics and the planned invasion of Lombardy with Charles I of Naples, caused a war with Oberto Pelavicino, the chief Ghibelline commander in the region, in 1264. William resisted him with determination and effectiveness, occupying the fortresses of Acqui Terme, Tortona, and Novi Ligure, and affirming his hold on Nizza Monferrato. In 1265, French reinforcements arrived. Less than eight years from his accession, William had extended his power to Lanzo and the vicinity of Alessandria. War against Charles I of Naples Though aided immensely by the Angevins, the lords of Montferrat had never been known for loyalty to a cause or party and William was