Mohammed II was only twenty years old when he took up the reins of government. He was ambitious, was endowed with great physical endurance, and, from reading the deeds of Julius Cæsar and Alexander, as they appeared in the folklore tales translated into Arabic, had conceived a strong desire to transform the tribal and loosely organized sovereignty of his people into an enduring political power with a systematic organization. His primary object was the capture of Constantinople, and to get a free hand for this undertaking, he adopted a most pacific policy in the first year of his reign. He renewed the treaties with Genoa and Venice, with the princes of Servia and Wallachia, and with Hunyadi, Scanderbeg, and the Knights of Rhodes. [Illustration: MEDAL OF MOHAMMED II.] He opened hostilities with the Greeks by building, in an extraordinarily short space of time, a fortification on the narrow seas, near the imperial city, which enabled him to collect dues from all the vessels entering the harbor, and served as a point from which issued armed expeditions that captured nearly all the Greek territory outside the city walls. Meanwhile, some slight acts of aggression in the Morea failed to reveal to the West the real purposes of the new Sultan. Those who had seen him spoke of him as a mild and learned young man, not at all the kind of ruler who would walk in footsteps different from his father’s. The Western Emperor, Frederick III, thought it was sufficient to write the Sultan a letter, warning him not to attack Constantinople. Those who were nearer understood his temper better, knowing that, when Constantine sent a delegation to protest against the erection of the fortification that had lately been built on the European shore of the Bosphorus, the Greek emissaries had been beheaded. In the doomed city itself dissensions reigned supreme. Ecclesiastics had come from Rome to look over the religious situation in Constantinople with the purpose of reporting the prospects for carrying out the terms of union, drawn up lately at the Council of Florence. Their appearance in the city disgusted the common people, who called their new Emperor a traitor to the Eastern Church, and an irreligious usurper, who was, after all, they said, not a real emperor, because he had not been crowned. The Venetians were busy looking after their own interests on the Adriatic coast or in continental Greece. They were busy arranging terms with the Sultan, as to the export of grain from Asia, and were so pleased with their commercial success in this bargain that they only resolved to allow artillerymen to be hired among the subjects of Venice by Constantine, not to aid him officially.