There he received tidings which tended to encourage him still more. Charles III., Duke of Savoy, although he was the maternal uncle of François I., had followed the counsel of his new wife, Beatrice, daughter of Emmanuel of Portugal, and had abandoned the party of the King of France; so that when François, by virtue of his former treaties with Charles III., called upon him to receive his troops, the Duke of Savoy answered by refusing to do so, and François was reduced to the unenviable necessity of forcing the passage of the Alps, which he had hoped to find open to him by favor of his ally and kinsman. But Charles X. was awakened from his feeling of security by a veritable thunder-clap. The king marched an army into Savoy so promptly that the duke found his province actually under occupation by the French troops before he suspected that it was invaded. Biron, who was in command of the army, seized Chambéry, appeared upon the Alpine passes, and threatened Piedmont just as Francesco Sforza, terror-stricken doubtless by the news of Biron's success, died suddenly, leaving the Duchy of Milan without an heir, and thereby not only making its conquest an easy matter for François, but giving him a strong claim to it as well. Biron marched down into Italy, and seized Turin. There he halted, pitched his camp on the banks of the Sesia, and awaited developments. Charles V. meanwhile had left Naples for Rome. The victory he had won over the long time enemies of Christ procured him the honor of a triumphal entry into the capital of Christendom. This entry intoxicated the Emperor to such a point, that, contrary to his custom, he went beyond all bounds, and in full consistory accused François I. of heresy, basing the accusation upon the protection he accorded the Protestants, and upon his alliance with the Turks. Having recapitulated all their former causes of disagreement, wherein, according to his view, François was always the first at fault, he swore to wage a war of extermination against his brother-in-law. His disasters in the past had made François as prudent as he formerly was reckless. And so, as soon as he found himself threatened at one time by the forces of Spain and of the Empire, he left D'Annebaut to guard Turin, and called Biron back to France, with orders to devote himself entirely to protecting the frontiers. Those who were familiar with the chivalrous and enterprising character of François were at a loss to understand this retrograde movement, and supposed from his taking one backward step that he considered himself whipped in advance. This belief still further exalted the pride of Charles V.; he took command of his army in person, and resolved upon invading France from the south.