Whilst the war was being carried on in Hungary, the king of Persia sent an embassy to the emperor of Germany and the princes of the West, to persuade them to form an alliance with him against the Turks. The Persian ambassadors repaired to the court of the sovereign pontiff, and to those of several Christian powers, conjuring them to declare war against the Ottomans. This embassy of the king of Persia, and the exploits of the French on the Danube, created great uneasiness in the Divan, and an ambassador was sent to the king of France, as the most to be feared of the Christian princes. The letters of credit of the Turkish envoy bore this title: “To the most glorious, magnanimous, and greatest lord of the faith of Jesus, pacificator of the differences which arise among Christian princes, lord of greatness, majesty, and riches, and glorious guide of the greatest, Henry IV., emperor of France.” The sultan of the Turks conjured the French monarch, in his letter, to bring about a truce between the Porte and the emperor of Germany, and to recall from Hungary the duke of Mercœur, whose valour and skill brought victory to the banners of the Germans. Henry IV. interrogated the Ottoman ambassador, and asked him why the Turks dreaded the duke of Mercœur so much. The ambassador replied, that a prophecy, credited by the Turks, declared that the sword of the French would drive them from Europe, and overthrow their empire. Henry IV. did not recall the duke of Mercœur: this able captain continued to beat the Ottomans, and having covered himself with glory in the war against the infidels, he was seized, whilst on his return to France, by a purple fever, “which,” says Mezerai, “sent him to triumph in heaven.” In their wars against the Christians, the Turks often found themselves on the defensive, which was for them a sign of decline. History remarks that at no period did their reverses cause them more alarm, or their victories more surprise and joy. Their defeats were almost always a signal for sedition and revolt, which the decline of power rendered bold. And yet the Ottoman empire still carried on war, and advanced like a storm ready to burst. In the middle of the seventeenth century, the isle of Chio, which had belonged to the Genoese, was added to its maritime possessions, and the Turks directed their victorious arms towards Candia, an important colony of the Venetians. At the same time an Ottoman army entered Transylvania, and greatly alarmed Austria. Pope Alexander VII., pressed by the emperor Leopold I. and by the Venetian senate, endeavoured to form a league among the princes and states of Christendom, and addressed the king of Poland, the king of Spain, and more particularly the king of France, to implore their succour against the Turks.