Despite his vigor and his authority, Innocent's constant interference with the internal concerns of every country in Europe did not pass unchallenged. Even the kings who invoked his intercession were constantly in conflict with him. Besides his great quarrels in Germany, France, and England, Innocent had many minor wars to wage against the princes of Europe. For five years the kingdom of Leon lay under interdict because its king Alfonso had married his cousin, Berengaria of Castile, in the hope of securing the peace between the two realms. It was only after the lady had borne five children to Alfonso that she voluntarily terminated the obnoxious union, and Innocent found it prudent, as in France, to legitimize the offspring of a marriage which he had denounced as incestuous. Not one of the princes of the peninsula was spared. Sancho of Navarre incurred interdict by reason of suspected dealings with the Saracens, while the marriage of his sister with Peter of Aragon, the vassal of the Pope, involved both kings in a contest with Innocent. Not only did the monarchs of Europe resent, so far as they were able, the Pope's haughty policy; for the first time the peoples of their realms began to make common cause with them against the political aggressions of the papacy. The nobles of Aragon protested against King Peter's submission to the papacy, declared that his surrender of their kingdom was invalid, and prevented the payment of the promised tribute. When John of England procured his Roman overlord's condemnation of Magna Charta, the support of Rome was of no avail to prevent his indignant subjects combining to drive him from the throne, and did not even hinder Louis of France, the son of the papalist Philip II, from accepting their invitation to become English king in his stead. It was only by a repudiation of this policy, and by an acceptance of the Great Charter, that the papacy could secure the English throne for John's young son, Henry III, and thus continue for a time its precarious overlordship over England. For the moment Innocent's iron policy crushed opposition, but in adding the new hostility of the national kings and the rising nations of Europe to the old hostility of the declining empire, Innocent was entering into a perilous course of conduct, which, within a century, was to prove fatal to one of the strongest of his successors. The more political the papal authority became, the more difficult it was to uphold its prestige as the source of law, of morality, of religion. Innocent himself did not lose sight of the higher ideal because he strove so firmly after more earthly aims. His successors were not always so able or so high-minded. And it was as the protectors of the people, not as the enemies of their political rights, that the great popes of the eleventh and twelfth centuries had obtained their wonderful ascendency over the best minds of Europe.