The Duke of Northumberland, who had scrambled into power on the shoulders of the Catholic party, deserted his former allies, and went over completely to the party of Cranmer, Ridley, and Hooper. Taking advantage of England's peaceful relations with France and Scotland and of the difficulties of the Emperor in Germany, he had risked everything to make England a Protestant nation. He had removed the bishops whose influence he feared, and had packed the episcopal bench with his own nominees. He had destroyed the altars and burned the missals to show his contempt for the Mass, and his firm resolve to uproot the religious beliefs of the English people. So determined were he and his friends to enforce the new religious service that even the Princess Mary was forbidden to have Mass celebrated in her presence, and her chaplains were prosecuted for disobeying the king's law. Once indeed the Emperor felt it necessary to intervene in defence of his kinswoman, and to warn the council that if any attempt were made to prevent her from worshipping as she pleased, he would feel it necessary to recall his ambassador and to declare war (1551). The situation was decidedly embarrassing, and the council resolved to seek the advice of Cranmer, Ridley, and Hooper. The bishops replied that though to give licence to sin was sinful Mary's disobedience might be winked at for the time.[68] The suggestion was followed by the council, but later on when the Emperor's hands were tied by the troubles in Germany, the attempt to overawe the princess was renewed. Mary, however, showed the true Tudor spirit of independence, and, as it would have been dangerous to imprison her or to behead her, she was not pushed to extremes.