Second Lateran Council, there arguing the cause of Frederick against Otto. He travelled many subsequent times into Germany to speak to Frederick and during these absences, his enemies plotted against him. In their attempts to seize his lands, however, they were largely unsuccessful. During his times in Italy, William remained at war with Asti and Alessandria, but without result. Claims in Greece Following his father's death in 1207, his conquests in Greece, formed into the Kingdom of Thessalonica, passed into the hands of William's half-brother Demetrius. The succession was opposed by the Lombard nobles of the kingdom, led by the regent Oberto II of Biandrate, who preferred the crown to pass to William. William himself was reluctant to claim the throne, and with the support of Latin Emperor Henry of Flanders, the rebellion of the Lombard barons was overcome, and Demetrius was crowned king. During the exhausting years battling rebels and Guelphs, William at last resolved to travel to Greece to defend the conquests of his father. To this end he was urged by the churchmen of his realm and also by the troubadour Elias Cairel. When he finally decided to take the cross, aware of the insignificance of his contribution to the total effort, he decided to head by way of Egypt, at the suggestion of Pope Honorius III. But the arrival of Demetrius, fleeing the onslaught of the Greeks under Theodore Komnenos Doukas and the hostility of the Lombard barons, led by Biandrate, convinced him to go to Greece. Several times he prepared to head out, but each time was detained by the threats of his enemies in Piedmont or by economic restraints which compelled him to mortgage his marquisate to Frederick II. Finally, he cowed some cities into giving him aid in men. Nevertheless, he was present at Capua, Ferentino, and Sora with Frederick II in February 1223. Delayed again and again, he drank a toast at Brindisi to his setting off in 1224, but he fell ill at the last minute. His fleet remained in port until the spring of 1225, when, under urging from Honorius, it finally cast off. The delays had been fatal and William himself died at Almyros in September 1225. The rest of his army was hit by a dysentery epidemic and melted away. Marriages and children On 9 August 1202 William married Berta (1182–1224), daughter of Marquis Bonifacio di Clavesana, count