After his father, Robert the Leper, was executed by the atabeg (or governor) of Toghtekin in 1119, William inherited Balatanos and Saone.
William was the son of Robert the Leper, who held important fiefs in the Principality of Antioch.
[5] Historian Thomas Asbridge says, William may have been one of the barons who persuaded the king to pursue an aggressive policy against the Muslims of Aleppo.
[6] Indeed, the 13th-century historian, Ibn al-Adim, mentioned that Baldwin II laid siege to Zardana "for William" in 1121.
[11] William and his brother supported her, but Fulk defeated her allies and appointed Rainald I Masoir to administer the principality.