The Sultan Murad II., who had so long looked with indulgent eye on the remnant of the Byzantine Empire, died in 1451. His son and successor, Mohammed II., was a young man of twenty-one years: a very able, highly cultivated and extremely ambitious young prince. To him the existence of this Christian island, the city of Constantinople, in the ocean of Mohammedan conquest was an intolerable anomaly. The Turks had long since carried the crescent over what we now call Turkey in Europe, and it was only by sea that Constantinople could communicate directly with the other Christian powers. To put an end to this Christian avenue into the heart of his dominion and make the great city the capital of the Mohammedan world was the early ambition of Mohammed II. Probably every sultan for a hundred years or more had desired this, but their siege machinery had hitherto proved incapable of shattering the stout old walls of that city. Constantine XI. underrated the young Sultan, and very soon gave him a pretext for an attack. Mohammed had signed a truce with the Hungarians, and gone to settle certain disturbances in his Asiatic dominions, when he received a most insolent and offensive message from Constantinople. He must at once increase the pension of Prince Orkhan (the nephew of Suleiman, then living in retirement at Constantinople), or else the Greeks will consider Orkhan’s claim to the Turkish throne. It was the last blunder of the Paleologi. Mohammed courteously heard and dismissed the legates, and proceeded to pacify his Asiatic province. Constantine had grossly failed to appreciate the young Sultan’s character. After his coronation at Adrianople his Christian vassals--the Emperors of Trebizond and Constantinople, the Duke of Athens, etc.--had hastened to do homage, and had seen only an accomplished, amiable and, in private life, vicious young man, from whom they had little to fear. Shortly afterwards the Court at Constantinople was alarmed to hear that a large army of Turkish workmen had arrived at a spot on the Asiatic coast only five miles from the city, and were, with great rapidity, building a powerful fort which would command the entrance to the Black Sea. Constantine sent a protest; Mohammed disdainfully replied that he would do as he liked in his own dominions. In time the Turkish soldiers of the district fell to quarrels with Constantine’s subjects, and the Emperor, ordering the gates of the city to be closed, demanded some recompense. Mohammed at once declared war, and went to Adrianople to concentrate his forces and gather a more powerful armament than his predecessors had used. The value of powder was now realized, and, although they were crude objects of only moderate effectiveness, immense cannons, which could throw stone balls weighing more than a hundred pounds, were associated with the old rams and slings and towers.