There were now many Ottoman princes, no longer one sultan. Souliman, who reigned at Adrianople, sought the protection of Manuel, gave him as a hostage one of his sisters, married a niece of the Emperor, restored part of Macedonia and Ionia, and yielded up Thessalonika, the greatest prize of all. When he was succeeded by his brother Mousa, there was an outbreak of hostilities; Thessalonika was again lost by the Greeks, but soon retaken, while a Turkish fleet was resisted by a fleet now manned by Greek sailors; for Manuel had taken care to provide for a navy, and was no longer dependent on the commercial cities of Italy. Mohammed was summoned by Manuel from Asia as an ally against Mousa, and the two succeeded in defeating him. On his capture he met death at Mohammed’s hands. For the next eight years (1413-1421) Mohammed was sole ruler of the Osmanlis, but internal difficulties hindered aggressive action on his part, so far as the Christian powers were concerned. His policy was decidedly philhellenic, Manuel receiving from his hands important territories on the Black Sea and the Propontis; but his main attention was directed to the Asiatic provinces, where, in addition to troubles with the emir of Karamania, there were disturbances, due to religious agitations in Islam. One of the chief agitators was a converted Jew, Torlak-Hin-Kemali, a preacher of the revolutionary doctrines of liberty and equality, who demanded a division of property. This communistic teaching stirred up the masses of the people, and excited the active sympathy of the dervish party. On the death of Mohammed, his son, Murad II, took up the succession. He was a prince of energy and ability, who devoted himself for thirty years to the restoration of the Empire. The Greek Emperor Manuel still carried on his policy of sowing dissension among the Turks, but with less success than in the preceding period. Mustafa, an uncle of the new Sultan, became the ally of the Greeks, and Gallipoli, the first place taken by the Turks in Europe, was besieged. Murad hastened personally to save the town from capture. His uncle was taken, beaten, and hanged. Murad undertook then to lay siege to Constantinople, this making the fourth time that the city had been threatened by Ottoman armies. (June, 1422.) The besiegers were a motley host; mixed with the soldiers were dervishes, marabouts (religious teachers), artisans, and peasants, all drawn together by the hope of sacking the rich capital.