domains in mainland Albania which were still under Charles I's control, but they were landlocked and isolated from each other. They could communicate with each other only by sea but the Byzantine fleet based in Spinarizza and Butrint kept them under constant pressure. Charles also managed to keep the island of Corfu. Michael VIII also scored another important diplomatic victory on Charles I by agreeing to unite the two churches in the Second Council of Lyon in 1274. Enthusiastic from the results of the council, Pope Gregory X, forbade any attempt by Charles on Michael VIII's forces. Under these circumstances Charles of Anjou was forced to sign a truce with Michael VIII in 1276. Angevin counteroffensive The Byzantine presence in Butrint alarmed Nikephoros I Komnenos Doukas the Despot of Epirus. He contacted Charles of Anjou and his vassal William II of Villehardouin who was at that time the prince of Achaea. Nikephoros I promised to make an oath of homage to Charles of Anjou in return for some land property in Achaia. In 1278 Nikephoros I's troops captured the city of Butrint. In March 1279 Nikephoros I declared himself a vassal of Charles of Anjou and surrendered to him the castles of Sopot and Butrint. As a pledge, Nikephoros I delivered his own son to the Angevin castellan of Vlorë to be held as hostage. Ambassadors were exchanged in this occasion, but Charles did not wait for the formalities to end; instead he ordered his captain and vicar-general at Corfu to capture not only Butrint, but everything that once belonged to Manfred and now were under the Despotate of Epirus. At the same time Charles began creating a network of alliances in the area in the brick of the new offensive, which would have pointed first to Thessaloníki and later to Constantinople. He entered in alliance with the kings of Serbia and Bulgaria. He also tried to get the support of the local Albanian nobles. After continuous requests from other Albanian nobles, he liberated from Neapolitan prisons a number of Albanian nobles who were arrested before being accused of collaborating with Byzantine forces. Among them were Gjin Muzaka, Dhimitër Zogu and Guljem Blinishti. Gjin Muzaka especially was important to Charles' plans because the Muzaka family territories were around city of Berat. They were liberated, but were ordered to send their sons as hostages in Naples. On August 1279, Charles of