Notwithstanding that he owed his crown to a popular revolution, Louis Philippe attached the highest importance to the natural alliances of the Bourbons. The maintenance of relations with Spain on the footing of consanguinity was, in consequence, the constant aim of his policy. In the pursuit of this object he found a ready instrument in his Foreign Minister. By upholding the principle that Isabella's husband must be a descendant of Philip V., M. Guizot purposed to disprove the reproach of his opponents that this foreign policy was weak and subservient to England.[873] His motives are perfectly comprehensible. But the reasons which induced the King to break the compact of Eu, by consenting to allow his son's marriage to take place at the same time as that of the Queen, have never been satisfactorily explained. Louis Philippe was very angry upon learning, on July 20, 1846, that M. Bresson, in order to overcome Christina's repugnance to the Duke of Cadiz, had held out to her the inducement that Montpensier's marriage with the Infanta might be concluded simultaneously. Turning a deaf ear to the timid remonstrances of M. Guizot, he insisted upon the necessity of acquainting the Queen-Mother that his ambassador had greatly exceeded his instructions. His private correspondence, discovered at the Tuileries after the Revolution of '48, makes his sentiments upon that point absolutely clear.[874] Nevertheless, in the course of the next three weeks all his scruples vanished, and he allowed M. Bresson to be furnished with the powers necessary for the conclusion of the double marriage.