Norway, which was united with Denmark at this period, was forced into submission to the new creed by the violence of the Danish kings, aided as they were by the greedy nobles anxious to share in the plunder of the Church. Similarly Iceland, which was subject to Denmark, was separated from Rome, though at first the people offered the strongest resistance to the reformers. The execution, however, of their bishop, John Aresen, the example of Denmark and Norway, and the want of capable religious leaders produced their effects, and in the end Iceland was induced to accept the new religion (1551). For a considerable time Catholicism retained its hold on a large percentage of the people both in Norway and Iceland, but the severe measures taken by the government to ensure the complete extirpation of the Catholic hierarchy and priesthood led almost of necessity to the triumph of Lutheranism. By the Union of Kalmar (1397) Sweden, Norway, and Denmark were united under the rule of the King of Denmark. The Union did not, however, bring about peace. The people of Sweden disliked the rule of a foreigner, and more than once they rose in rebellion against Denmark. In the absence of a strong central authority the clergy and nobles became the dominant factors in the state, especially as they took the lead in the national agitations against King Erik and his successors. As in most other countries at the time, the Church was exceedingly wealthy, the bishoprics and abbacies being endowed very generously, but unfortunately, as elsewhere, the progress of religion was not in proportion to the worldly possessions of its ministers. Endowment had destroyed the liberty of election so essential for good administration, with the result that the bishops and other ecclesiastical dignitaries were selected without much regard for their qualifications as spiritual guides. Yet it must be said that in general the administrators of the ecclesiastical property were not hard task-masters when compared with their lay contemporaries, nor was there anything like a strong popular feeling against the Church. Still the immense wealth of the religious institutions, the prevalence of abuses, and the failure of the clergy to instruct the people in the real doctrines of their faith were a constant source of menace to the Church in Sweden, and left it open to a crushing attack by a leader who knew how to win the masses to his side by proclaiming himself the champion of national independence and of religious reform.