Kayqubad I
Constantine of Baberon, the regent for Isabella of Cilicia, offered her hand to Bohemond's son, Philip, because he needed Bohemond's assistance against Kayqubad I, Sultan of Rum. Bohemond accepted the offer and his son married Isabella in June 1222. Bohemond and Philip repelled a Seldjuq attack against Cilicia. Philip's blatant favoritism towards his Frankish retainers enabled Constantine of Baberon to hatch a plot against him. Philip and his supporters were captured and imprisoned at the end of 1224. Bohemond tried to ensure his son's liberation through negotiations. He appealed to Pope Honorius III, but the pope confirmed his excommunication and forbade the Templars to assist him. Bohemond persuaded Kayqubad I to invade Cilicia. Although Bohemond's son had already been poisoned, Constantine of Baberon promised that Philip would be released if Bohemond come to Cilicia. Shortly after Bohemond's departure, Shihab ad-Din Toghril, atabeg of Aleppo, broke into the Principality of Antioch. After learning of his son's death and Toghril's invasion, Bohemond hurried back.