As the lines of expansion in the East and in Africa had been closed by the remarkable achievements of Selim, Souliman’s hands were free to take up the traditional line of aggressive progress of Turkish power. Hungary was attacked on the ground that the payment of tribute was refused. In 1521, after two important battles, Belgrade was besieged by the Sultan; the fate of the city was decided by the defection of its Servian and Bulgarian allies. Twenty assaults were made, and there were only 400 able-bodied men in the garrison, when a mutiny among the inhabitants forced the town to capitulate on August 29, 1521. The conquest of Rhodes, the center of Christian resistance in the East, was now not long delayed. A large navy of 200 vessels appeared off the island with a summons to the grand master, Villiers de l’lsle Adam, to surrender. Souliman had collected an army of 100,000 men to undertake the siege, but the defenders were not terrified. Every assault made on the great bastions of the citadel caused enormous losses among the Turks; but their prolonged artillery fire and the new supplies of men, drawn constantly from Asia, showed the mere handful of defenders that their struggle could have only one outcome. In December, 1522, the island capitulated on terms that were favorable to the heroic defenders; even the Sultan appreciated the tragedy, for he is recorded to have said to his favorite Ibrahim, that he was loath to force this Christian commander, in his old age, to leave his house and his goods. [Illustration: SULEYMAN THE MAGNIFICENT (In Youth.)]