The Dano-Swedish War of 1658–1660 was a war between Denmark–Norway and Sweden, with the former backed by the Dutch Republic and Poland. It is known in Denmark as the Second Karl Gustav War (Danish: Anden Karl Gustav-krig), in Norway as Bjelkes Feud (Norwegian: Bjelkefeiden) in Sweden as Karl Gustav's Second Danish War (Swedish: Karl Gustavs andra danska krig), and in the Netherlands as the Swedish-Dutch War (Dutch: Zweeds-Nederlandse Oorlog).
It was a continuation of an earlier conflict between the two belligerents which had ended just months earlier, after Sweden and Denmark brokered a peace agreement in Roskilde in 1658. In the aftermath of that conflict, the Swedish king Charles X Gustav desired to add the province of Royal Prussia in Poland to the Swedish realm, but his position in the region was not strong enough with the opposition of Brandenburg and Austria. However, the Danes stalled and prolonged the fulfillment of some provisions of the earlier peace; the Swedish king decided to use this as a pretext to attack with an ambitious goal: to vanquish Denmark as a sovereign state and raze the capital of Copenhagen. A quick and decisive defeat of Denmark was however only seen as a means to a greater end. The long-term goal was to wage war in Europe without fearing Danish interference.
