However, after the death of William in 1278, the seeds of a calamitous succession dispute were laid. In the normal course of events, Achaea would have passed to a cadet branch of the House of Anjou. However, his son-in-law Philip had died in 1277 without an heir, and a reversionary clause in the Treaty of Viterbo provided that the Principality would go to Charles of Anjou, rather than Isabelle, should this occur. Charles duly took possession of the Principality, which he ruled through a series of baillis; he would never personally visit it.