This dynastic revolution strengthened Sweden by making her religion the symbol and the test of her liberty. Lutheranism became the political as well as the religious faith of the country. It weakened her by adding another to the number of her hereditary foes. If Denmark could not forget that she had once been the ruler of Sweden, neither could Poland forget, at any rate during the life of Sigismund, that her king had by law no less right to rule at Stockholm than at Warsaw. If, however, Charles IX. increased the external he diminished the internal difficulties of his country. Nobles and king had united together against foreign influence, and when raised to the throne, Charles succeeded by his wise administration in making the bond still closer and was able to hand on to his son, the young Gustavus Adolphus, the government of a united and prosperous nation. Nevertheless, patriotic and religious as Sweden was on the accession of Gustavus Adolphus in 1611, she had not yet passed through that crisis common to the infancy of nations, when extension of territory and influence becomes essential to the preservation of national-life. Since she had become an independent nation her mineral wealth had been much developed by her kings. Education and civilisation had made great strides. Since she had become Protestant, she had naturally been drawn into political and commercial relations with the English and the Dutch, who were rapidly establishing their commercial supremacy in the northern seas, and especially in the Baltic, on the ruins of the Hansa. [Sidenote: =Weakness of Sweden.=] But as yet Denmark held the southern provinces of the Swedish peninsula. Only in one place, at the mouth of the river Gota, where the fortress of Elfsborg stood and the houses and wharves of Gottenburg were beginning to rise, did Sweden touch the outer sea. For all practical purposes her trade was a purely Baltic trade, and could only reach the outside world by the permission, and subject to the regulations, of Denmark, who held the Sound and imposed tolls on all ships which passed through. [Sidenote: =Policy of Gustavus Adolphus.=]