The Turks in less than a generation after the withdrawal of Timour recovered all their influence and territory. Manuel was compelled even as early as 1403 to recognise Bajazed’s successor, Suliman (to whom, indeed, he gave his granddaughter in marriage), as lord of a large portion of Thrace. Suliman, however, proved himself a weak and worthless leader of the Turks, and in 1409 the Janissaries, preferring his brother Mousa, arrested and killed him. He was succeeded by Mahomet, the first of that name in the Ottoman dynasty, who had been aided by Manuel and who in return gave back to the emperor the fortified places on the Marmora and Black Sea which had been in the occupation of the Turks: an almost solitary instance of this kind of generosity on the part of the Turks, who hold as a religious principle that they must only surrender territory to force. Mahomet had, however, given his promise to Manuel and, says Ducas, he faithfully kept it.[99] During the next few years and until the death of the sultan, Manuel’s relations with him were friendly. In 1415 the two sovereigns had an interview at Gallipoli. Although the Turks were pursuing their encroachments in Hungary and Dalmatia, Mahomet abstained from attacking the empire. When they carried off nearly two thousand captives into slavery from Euboea, its Venetian rulers were compelled to seek the mediation of Manuel in order to obtain peace. Five years afterwards, Mahomet in passing to his dominions in Asia Minor went by way of the capital, and Phrantzes testifies that, in spite of suggestions to seize him, Manuel refused to violate the right of hospitality. So great was the sultan’s trust in the emperor that Mahomet named Manuel as the guardian of his two younger sons. Murad, the eldest son and successor of Mahomet, who became sultan in 1420, proposed a renewal of the alliance with Manuel. The latter would probably have consented. He was overruled, however, by the senate, which was in favour of a policy of war and decided that John should be associated with his father. A demand was made to Murad to send his two younger brothers to Constantinople, and the grand vizier returned the answer which might have been expected, that the education of two Mussulmans could not be entrusted to the enemies of their faith--believers to be educated by infidels.[100] War followed, and the Greeks supported a pretender to the Turkish throne, who was soon defeated and hanged by Murad. [Sidenote: Siege of Constantinople by Murad, 1422.]