power of the north. But although the Swedes gradually extended their sway over Dalecarlia and Finland, their further extension was prevented by the advance of the Russians of Novgorod to the shores of the Gulf of Finland; and thus the peoples of the north were once more thrown back upon themselves.
After several unsuccessful attempts at dynastic union, the three kingdoms were at length united. In 1363 Valdemar III (Atterdag) of Denmark had given his daughter Margaret in marriage to Hakon of Norway. On his death in 1375 Margaret's son Olaf became King of Denmark. Five years later, on the death of his own father, Olaf succeeded to the crown of Norway; and Margaret became the real ruler of both realms in the name of her son. About the same time she laid claim to the crown of Sweden in right of her late husband Hakon; and, although the claim was at first very shadowy, it became formidable when the Swedish nobles espoused her cause. The King, Albert of Mecklenburg, was defeated and made prisoner at the battle of Falköping; and the Treaty of Lindholm (1393) left her undisputed mistress of Sweden. Thus the three realms were united under Queen Margaret, for her son Olaf had died in 1387. The personal union before long became a constitutional one. In 1397 Margaret caused her grand-nephew Erik to be crowned King at Kalmar; and on that occasion there was concluded, by nobles representing the three kingdoms, the famous Union of Kalmar, by which Sweden, Norway, and Denmark were declared to be for ever united under one King, each retaining its own laws and customs. But the Union was not regularly promulgated or made widely known, its terms were vague and indefinite, and they opened up more questions than they solved. It was provided that a son of the reigning King should be chosen if possible; but nothing was said as to the method by which the three kingdoms were to participate in the election. It was provided that all should take up arms against the general enemy; but no reference was made to the carrying out of projects which concerned one of the three only. It is plain that nothing but pressing common interests or a strong ruler could render such an agreement permanent, and this was precisely what was wanting. On the one hand, Erik and his successors really ruled in the interests of Denmark; on the other, the condition of Sweden, practically one of anarchy, made any settled government well-nigh impossible. Revolts were of frequent occurrence, and before long the Danish governors were driven out, and Karl Knudson, the leader of the higher nobility, became administrator (Riksfœrestandare) of Sweden. On the accession of the House of Oldenburg to the throne of Denmark in 1448, Karl Knudson was proclaimed King of Sweden, and soon afterwards of Norway also. Christian I soon regained his hold over the latter realm; but from this time forward the Danish Kings were seldom able to make good their claims over Sweden, which continued to be ruled by Swedish administrators until
