the Staufen Philip of Swabia who emerged as the preferred German candidate. When Philip was killed, Innocent revived his support of Otto in exchange for guarantees of papal independence, and when Otto showed total disregard of these guarantees and began a menacing foray into Italy the pope turned to the only remaining option, Frederick, supporting him through to victory over Otto in Germany. Frederick thus added Germany to Sicily despite the best efforts of the pope. All Innocent had gained was temporary control over Sicily, where Constance had made Frederick his ward, in a period of civil war, and perhaps more significantly promises, first made by Otto and confirmed by Frederick, of the independent territory in central Italy that was to become the papal state.
The new emperor returned to Italy, which became his base, in 1220, and within a few years the papacy's worst fears were realized. Frederick's initial efforts were directed towards bringing order to Sicily (the kingdom consisted of not just the island but also much of the boot of Italy from Naples downwards). Soon, however, he turned to the northern Italian towns, and summoned a diet, at Cremona, for 1226, with the purpose of restoring imperial rights in the area. The challenge galvanized the towns back into the concerted opposition which had developed, in the form of the Lombard League, in resistance to his grandfather Frederick Barbarossa. A majority of them defied Frederick, who backed down. By now he was forced to fulfil his promise to go on crusade, but when he returned he found himself up against not only the towns but also a new pope, Gregory IX, a nephew of Innocent III and an implacable opponent, who had used Frederick's period of absence to weaken his hold over Sicily as well as to consolidate opposition in the north of the peninsula. For the rest of his life Frederick was almost constantly locked in conflict in northern and central Italy. The death of Gregory IX saw Frederick menacing Rome, attempting to influence the choice of his successor. There followed two years without a pope, but the eventual choice, Innocent IV, was if possible even more uncompromising than Gregory. The new pope soon fled to Lyons, claiming that Frederick's pressure on Rome made it unsafe, and summoned
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