On the whole, Charles, in alliance with Henry VIII, was successful against Francis I and the Turk. Their chief battlefield was North Italy; the generalship was dull on both sides; their advances and retreats depended mainly on the arrival of reinforcements. The German army invaded France, failed to take Marseilles, fell back into Italy, lost Milan, and was besieged in Pavia. Francis I made a long and unsuccessful siege of Pavia, was caught by fresh German forces, defeated, wounded and taken prisoner. But thereupon the Pope and Henry VIII, still haunted by the fear of his attaining excessive power, turned against Charles. The German troops in Milan, under the Constable of Bourbon, being unpaid, forced rather than followed their commander into a raid upon Rome. They stormed the city and pillaged it (1527). The Pope took refuge in the Castle of St. Angelo while the looting and slaughter went on. He bought off the German troops at last by the payment of four hundred thousand ducats. Ten years of such confused fighting impoverished all Europe. At last the Emperor found himself triumphant in Italy. In 1530, he was crowned by the Pope—he was the last German Emperor to be so crowned—at Bologna. Meanwhile the Turks were making great headway in Hungary. They had defeated and killed the king of Hungary in 1526, they held Buda-Pesth, and in 1529 Suleiman the Magnificent very nearly took Vienna. The Emperor was greatly concerned by these advances, and did his utmost to drive back the Turks, but he found the greatest difficulty in getting the German princes to unite even with this formidable enemy upon their very borders. Francis I remained implacable for a time, and there was a new French war; but in 1538 Charles won his rival over to a more friendly attitude after ravaging the south of France. Francis and Charles then formed an alliance against the Turk. But the Protestant princes, the German princes who were resolved to break away from Rome, had formed a league, the Schmalkaldic League, against the Emperor, and in the place of a great campaign to recover Hungary for Christendom Charles had to turn his mind to the gathering internal struggle in Germany. Of that struggle he saw only the opening war. It was a struggle, a sanguinary irrational bickering of princes, for ascendancy, now flaming into war and destruction, now sinking back to intrigues and diplomacies; it was a snake’s sack of princely policies that was to go on writhing incurably right into the nineteenth century and to waste and desolate Central Europe again and again.