defenses. In April 1442, Demetrios and the Ottomans began their attack, but they were repulsed and Demetrios was briefly imprisoned. In March 1443, Sphrantzes was made governor of Selymbria in Constantine's name. From Selymbria, Sphrantzes and Constantine would be able to keep a watchful eye on the activities of Demetrios. In November, Constantine gave over control of Selymbria to Theodore, who in turn abandoned his position as Despot of the Morea, making Constantine and Thomas the sole Despots of the Morea. Theodore died in June 1448 and on 31 October of the same year, Emperor John VIII passed away. The potential successors to the throne were Constantine, Demetrios and Thomas. John had not formally designated an heir, though everyone knew he favored Constantine and ultimately, the will of their mother, Helena Dragaš (who also preferred Constantine), prevailed. Both Thomas, who had no intention of claiming the throne, and Demetrios, who most certainly did, hurried to Constantinople and reached the capital before Constantine. Though Demetrios was favored by many due to his anti-unionist sentiment, Helena reserved her right to act as regent until her eldest son, Constantine arrived, stalling Demetrios's attempt at seizing the throne. Thomas accepted Constantine's appointment and Demetrios, who soon thereafter joined in proclaiming Constantine as his new emperor, was overruled. Soon thereafter, Sphrantzes informed Sultan Murad II, who also accepted the appointment. Despot of the Morea The Fall of Constantinople and early rule In order to remove Demetrios from the capital and its vicinity, Constantine made Demetrios Despot of the Morea, to rule the despotate together with Thomas. Demetrios was granted the despotate's nominal capital, Mystras, and primarily ruled the southern and eastern parts of the despotate, with Thomas ruling Corinthia and the north-west, variously using Patras or Leontari as his capital. During his tenure as despot, Demetrios made some efforts to expand the despotate, seizing the Venetian-held castle of Kastri. With him to the Morea, Demetrios brought a part of the ancient Asen family, which had once ruled the Second Bulgarian Empire. Demetrios married Theodora Asanina, daughter of Paul Asan. Theodora's brother Matthew Palaiologos Asen was appointed as governor of Corinth by Demetrios. Before his marriage to Theodora, Demetrios had been married either once or twice. His previous marriage(s) had not produced any children. His first wife was the daughter of Kantakouzenos Strabomytes, between 1430 and 1435. His second wife, possibly the same person as the