A graver problem, in the solution of which his character is often obscured, was presented by the struggle of Ghibellines (or followers of Philip of Swabia) and Guelphs (supporters of Otto of Brunswick) for the imperial crown. Frederic, the son and heir of Henry, being still a boy of tender years, his uncle Duke Philip of Swabia desired to keep the crown securely in the Hohenstauffen family by wearing it himself. Otto of Brunswick also made a fantastic claim to it, got himself proclaimed Emperor at Cologne in 1198, and sought the support of the Pope. Innocent undoubtedly favoured from the start the baseless claim of Otto. The Papacy had come to regard the Hohenstauffens almost as hereditary foes, and Philip actually lay under sentence of excommunication for holding the territory bequeathed by Mathilda to the Papacy; while Otto flattered the Pope by professions of loyalty and docility. But Philip had the better prospect, if there was an appeal to the sword, and Innocent refused for some years to commit himself. He summoned Philip to surrender the Italian prisoners and the Papal provinces taken by Henry, and sent the Bishop of Sutri to absolve him if he complied. To his extreme annoyance the not very clear-headed Bishop gave Philip an unconditional absolution--for which Innocent promptly imprisoned the Bishop for life in a monastery--and thus surrendered the Pope's chance of profiting by the situation. The rivals appealed to the sword, and Innocent bitterly complained that Philip did not ask his arbitration.[242] He alone, he declared to the princes and prelates of Germany, was the judge of such high causes: to which the princes and prelates replied, in very firm and dignified language, that they would have no Papal interference in the secular concerns of Germany.[243] As the war proceeded, Innocent made it clear that he favoured Otto. He warned the German prelates not to choose an Emperor on whom he could not bestow the crown, and in a letter to the Eastern Emperor he afterwards boasted that he alone kept Philip from the throne. But the war went in favour of Philip, and even when, in 1200, both men sent representatives to Rome, Innocent would not commit himself to more than an eloquent proof that priests were exalted above kings.[244] At the beginning of the following year, however, he declared openly for Otto. He sent Cardinal Pierleone to Germany with the Bull _Interest Apostolicæ Sedis_, in which he drew up a violent and unjust indictment of Philip and awarded the crown to the loyal and virtuous Otto. The Bull is painfully casuistic, and would have been better if it had stopped at the bold declaration that the Papacy had created the Empire and could bestow it according to its pleasure. While, for instance, it charges Philip with treachery to the interests of his young nephew, it exonerates all others from the oath of fidelity to Henry's son on the ground that an oath to an unbaptized infant was