Kalmar War, (1611–13), the war between Denmark and Sweden for control of the northern Norwegian coast and hinterland, which resulted in Sweden’s acceptance of Denmark-Norway’s sovereignty over the area.
Denmark’s king Christian IV declared war on Sweden in April 1611 after the Swedish king Charles IX claimed sovereignty over the old Finnmark region, a strategic point along the Atlantic–White Sea trade route that had long provided the Danish-Norwegian kings with fish and furs. Growing Swedish power in the eastern Baltic and the development of the Swedish port of Gothenburg beyond the Danish Sound (Øresund) were additional reasons for Christian’s action. The war was named for the Swedish port of Kalmar, which fell to the Danes in the summer of 1611. Swedish fortunes continued to ebb as their troops were forced out of Finnmark by the Norwegians, and the port of Älvsborg fell to the Danes in May 1612. The war ended with the signing of the Peace of Knäred in January 1613. By this treaty, Danish-Norwegian sovereignty over Finnmark was recognized, and Älvsborg was to be held by the Danes pending payment of a Swedish tribute, which was paid four years later.