The House of Guise claimed descent from Charlemagne and harbored pretensions to the French crown. In the reign of Francis II they attained supreme power, and sought to convert it to true kingship by eradicating the House of Bourbon, the legal successors to the throne of France. The leading Bourbon princes, Antoine, King of Navarre and Louis, Prince of Condé, were Protestants. To oppose the Bourbons, the Guises made themselves champions of the Catholic faith and allied themselves with Philip II of Spain.