Charles, after the treaty of Cambray was signed, visited Italy with all the pomp of a conqueror. At Genoa, he honored Doria with many marks of distinction, and bestowed upon the republic new privileges. He settled all his difficulties with Milan, Venice, and Florence, and reestablished the authority of the Medici. He was then crowned by the pope, whom he had trampled on, as King of Lombardy and Emperor of the Romans, and hastened into Germany, which imperatively required his presence, both on account of dissensions among the princes, which the reformation caused, and the invasion of Austria by three hundred thousand Turks. He resolved to recover the old prerogatives of the emperor of Germany, and crush those opinions which were undermining his authority, as well as the power of Rome, with which his own was identified. [Sidenote: Diet of Spires.] A Diet of the empire was accordingly summoned at Spires, in order to take into consideration the state of religion, the main cause of all the disturbances in Germany. It met on the 15th of March, 1529, and the greatest address was required to prevent a civil war. All that Charles could obtain from the assembled princes was, the promise to prevent any further innovations. A decree to that effect was passed, against which, however, the followers of Luther protested, the most powerful of whom were the Elector of Saxony, the Marquis of Brandenburg, the Landgrave of Hesse, the Duke of Lunenburg, the Prince of Anhalt, and the deputies of fourteen imperial cities. This protest gave to them the name of _Protestants_--a name ever since retained. Soon after, the diet assembled at Augsburg, when the articles of faith among the Protestants were read,--known as the Confession of Augsburg,--which, however, the emperor opposed. In consequence of his decree, the Protestant princes entered into a league at Smalcalde, (December 22, 1530,) to support one another, and defend their religion. Circumstances continually occurred to convince Charles, that the extirpation of heresy by the sword was impossible in Germany, and moreover, he saw it was for his interest--to which his eye was peculiarly open--to unite all the German provinces in a vigorous confederation. Accordingly after many difficulties, and with great reluctance, terms of pacification were agreed upon at Nuremburg, (1531,) and ratified in the diet at Ratisbon, shortly after, by which it was agreed that no person should be molested in his religion, and that the Protestants, on their part, should assist the emperor in resisting the invasion of the Turks. The Germans, with their customary good faith, furnished all the assistance they promised, and one of the best armies ever raised in Germany, amounting to ninety thousand foot, and thirty thousand horse, took the field, commanded by the emperor in person. But the campaign ended without any memorable event, both parties having erred from excessive caution. [Sidenote: Hostilities between Charles and Francis.]