I make no threats against your city. By assuring the safety of my country I am not infringing any treaty. Have you forgotten the extremity to which my father was reduced when your Emperor, in league with the Hungarians, endeavoured to prevent his crossing to Europe by closing the Straits against him? Murad was compelled to ask for the assistance of the Genoese. I was at Adrianople at the time and was very young. The Mussulmans were in great alarm and you Greeks insulted them. My father took an oath at the battle of Varna to erect a fort on the European side. This oath I will fulfil. Have you the right or the power to prevent my doing what I wish on my own territory? The two sides of the Straits are mine—that of Asia Minor because it is peopled by Ottomans, that of Europe because you are unable to defend it. Tell your master that the Sultan who now reigns in no way resembles his predecessors. My power goes beyond their vows. I permit you now to withdraw, but in the future I will have flayed alive those who bring me such messages.[14] No more envoys were sent to him after this by the Greeks. Their Emperor, Constantine—the last of his line—had succeeded his brother three years before the accession of Mahomet. He was a brave and conscientious prince, who gave lustre to the last days of the Empire. But he was most unwise and provocative in his conduct to the new Sultan, evidently under the belief that he had to deal with the inexperienced youth who had been displaced by Murad six years previously. He threatened to let loose, as a rival claimant to the Ottoman throne, Orkhan, a grandson of Bayezid, who was under his charge, if a larger allowance was not given for his maintenance. Mahomet contemptuously rejected the claim. The Grand Vizier, Khalil, who was suspected of being in the pay of the Greeks, warned the Emperor of his extreme folly. “Your madness,” he said to the Greek ambassador, “will put Constantinople in the hands of the Sultan. Proclaim Orkhan Sultan in Europe, call in the Hungarians to your aid, retake what provinces you can, and you will speedily see the end of the Greek Empire.” The new fortress was completed in the autumn of 1452. It was then seen that, in combination with the fortress on the opposite shore, it gave complete command of the Straits to the Ottomans. Venetian vessels which attempted to pass were captured and their crews were sawn in halves. Mahomet then declared his intention to attack Constantinople. In an address to his principal pashas, after describing the conquests made by his predecessors in Europe and Asia, he pointed out that the great barrier to further progress was this city and the army of the Emperor.