the Palaiologoi only being allowed to keep the south, including the despotate's nominal capital, Mystras, on the condition that they paid their annual tribute to the sultan. Almost as soon as Mehmed had left the Morea, the two brothers began quarreling with each other again. Mehmed's victory had only increased the antagonism between Thomas and Demetrios. Demetrios had shifted to becoming even more pro-Ottoman after Mehmed had promised the despot that he would marry his daughter Helena, whereas Thomas increasingly hoped for western aid as the regions of the Morea annexed by Mehmed had been almost the entire area ruled by Thomas, including his capital of Patras. In January 1459, Thomas rebelled against Demetrios and the Ottomans, joining with a number of Albanian lords. They seized the fortress of Kalavryta and much of the land in the central Morea and besieged Kalamata and Mantineia, fortresses held by Demetrios. Demetrios responded by seizing Leontari and called for aid from the Turkish governors in the northern Morea. There were many attempts made to broker peace between the two brothers, such as Mehmed ordering the Bishop of Lacedaemon to make the two swear to keep the peace, but any truce lasted only briefly. Many of the Byzantine nobles in the Morea could only look on in horror as the civil war raged on. Byzantine historian George Sphrantzes summed up the conflict with the following words:Although Demetrios had more soldiers and resources, Thomas and the Albanians were able to appeal to the West for aid. After a successful skirmish against the Ottomans, Thomas sent 16 captured Turkish soldiers, alongside some of his armed guards, to Rome to convince the Pope that he was engaging in a holy war against the Muslims. The scheme worked and the Pope sent 300 Italian soldiers under the Milanese condottieri Gianone da Cremona to aid Thomas. With these reinforcements, Thomas gained the upper hand and it looked as if Demetrios was about to be defeated, having retreated to the town of Monemvasia and having sent Matthew Palaiologos Asen to Adrianople to beg Mehmed for aid. Thomas's pleas to the west represented a real threat to the Ottomans, a threat made even greater through the support of the plan by the vocal Cardinal Bessarion, a Byzantine refugee who had escaped the empire years earlier. Pope Pius II convened a council in 1459 in Mantua and sent Bessarion and some others