The triumph of Lutheranism in the Scandinavian countries has been traced largely to political and economic causes. When Martin Luther broke with the Catholic Church, Christian II (1513-1523) was reigning as elected king over Denmark and Norway and had recently conquered Sweden by force of arms. The king encountered political difficulties with the Church although he maintained Catholic worship and doctrine and apparently recognized the spiritual supremacy of the pope. But Christian II had trouble with most of his subjects, especially the Swedes, who were conscious of separate nationality and desirous of political independence; and the king eventually lost his throne in a general uprising. The definite separation of Sweden from Denmark and Norway followed immediately. The Swedes chose the celebrated Gustavus Vasa (1523-1560) as their king, while the Danish and Norwegian crowns passed to the uncle of Christian II, who assumed the title of Frederick I (1523-1533). [Sidenote: Denmark] In Denmark, King Frederick was very desirous of increasing the royal power, and the subservient ecclesiastical organization which Martin Luther was advocating seemed to him for his purposes infinitely preferable to the ancient self-willed Church. But Frederick realized that the Catholic Church was deeply rooted in the affections of his people and that changes would have to be effected slowly and cautiously. He therefore collected around him Lutheran teachers from Germany and made his court the center of the propaganda of the new doctrine, and so well was the work of the new teachers done that the king was able in 1527 to put the two religions on an equal footing before the law. Upon Frederick's death in 1533, the Catholics made a determined effort to prevent the accession of his son, Christian III, who was not only an avowed Lutheran but was known to stand for absolutist principles in government.