of their number, Konstantin Tih, although he was not related to the ruling Asen dynasty. Expansion Theodore's war against Bulgaria brought about a rapprochement between Epirus and Serbia. Michael II of Epirus made a formal alliance with Stefan Uroš I, King of Serbia. He also sent gifts to the Albanian chiefs who had acknowledged Nicaean suzerainty to gain their support. Theodore's daughter, Maria, and Michael II's son and heir, Nikephoros, had been engaged during Vatatzes' reign. After making peace with the Bulgarians, Theodore ordered Michael II to send Nikephoros to Thessalonica to wed Maria. Nikephoros was accompanied by his mother, Theodora Petraliphaina. Theodore took her into custody, only allowing her to return to Epirus after Michael II ceded Servia and Dyrrachium to him. The possession of the two towns secured the Nicaean control of the Via Egnatia, but Michael II remained hostile to Theodore. Theodore received the papal legate, Bishop Constantine of Orvieto, in Thessalonica. Their negotiations proved fruitless, because the legate's authorization was limited and Theodore was unwilling to make concessions for the church union. He also preserved the right to convoke the Orthodox bishops to a synod to discuss the conditions of the union. Theodore maintained a correspondence with the Holy See, but he did not initiate new negotiations with it. The Mongols invaded Asia Minor and defeated Kaykaus II on 14 October 1256. Theodore hurried back to Anatolia to oversee the preparations for the defense. Kaykaus sought asylum in Nicaea and the Mongols installed his brother, Kilij Arslan IV, as the new sultan of Rum. Theodore assembled his troops on the plains near Magnesia. The Mongol ruler of Persia, the Ilkhan Hülagü, sent a delegation to Theodore to begin negotiations about Kaykaus' future. Hülegü agreed to withdraw his army from Rum and ordered the division of the sultanate between Kaykaus and Kilij Arslan in the spring of 1257. Before leaving for Rum, Kaykaus ceded four fortresses in the valley of the river Lycus to Nicaea in return for a contingent of 300 auxiliary troops. His achievements made Theodore self-confident. He proudly stated that his empire included territories as far as Dyrrachium on the Adriatic Sea and Cape Karambis on the Black Sea. His success during the war against Bulgaria had convinced him he should recruit soldiers from among Anatolian peasants. In a letter to Blemmydes, he stated that the native "Hellenes" were more reliable than foreign mercenaries.