According to the new rules of succession the oldest legitimate son, if qualified for the office, should inherit the throne. The oldest might be passed over, however, in favor of a younger legitimate son, or even in favor of an illegitimate descendant, if the bishops should find such a procedure expedient. See Gjerset, _History of the Norwegian People_, I, 364. The new arrangement did not long remain unchallenged. In 1177 the opposition to the ecclesiastical faction found a leader in Sverre, called Sigurdsson, an adventurer from the Faroe Islands, who pretended to be a grandson of Harold Gilchrist, though the probabilities are that his father was one Unas, a native of the Faroes.[87] Sverre’s followers were known as Birchshanks, because they had been reduced to such straits that they had to bind birch bark around their legs. The faction in control of the government was called the Croziermen and was composed of the higher clergy with an important following among the aristocracy. Sverre’s fight was, therefore, not against King Magnus alone but against the Guelph party of Norway. For half a century there was intermittent civil warfare between the supporters of an independent and vigorous kingship on the one side and the partisans of clerical control on the other. King Sverre’s great service to Norway was that he broke the chain of ecclesiastical domination. The conflict was long and bitter and the great king died while it was still on; but when it ended the cause of the Croziermen was lost. The church attained to great power in the Norwegian state, but it never gained complete domination. Footnote 87: While it seems probable that Sverre was not of royal blood he was not necessarily an impostor; he may have believed his mother’s assertions. For a discussion of the problem see _ibid._, 376-377. Sverre was a man of great intellectual strength; he was a born leader of men, a capable warrior, and a resourceful captain. When it began to look as if victory would crown his efforts, the archbishop fled to England and from his refuge in Saint Edmundsbury excommunicated the king. But exile is irksome to an ambitious man, and after a time the fiery prelate returned to Norway and was reconciled to the strenuous ruler. Eystein’s successor, however, took up the fight once more; and when Sverre made Norway too uncomfortable for him, he fled to Denmark and excommunicated his royal opponent. A few years later, Innocent III, who had just ascended the papal throne, also excommunicated Sverre, and threatened the kingdom with an interdict.[88] But the papal weapons had little effect in the far North; the king forced priests and prelates to remain loyal and to continue in their duties. No doubt they obeyed the excommunicated ruler with great reluctance and much misgiving; but no other course was possible, for the nation was with the king. Footnote 88: