The Dano-Swedish War of 1658–60 is a war between Denmark–Norway and Sweden.

It is a continuation of an earlier conflict between the two belligerents that 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 desires to add the province of Royal Prussia in Poland to the Swedish realm, but his position in the region is not strong enough with the opposition of Brandenburg and Austria.

However, the Danes stall and prolong the fulfillment of some provisions of the earlier peace; the Swedish king decides 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 is however only seen as a means to a greater end.

The long-term goal is to wage war in Europe without fearing Danish interference.The Swedish army surrounds Copenhagen, hoping to starve it into submission.

This fails when the Dutch Republic joins the conflict on the Danish side and a reinforcing fleet manages to smash its way through the Swedish naval forces in Øresund.

Charles then tries a decisive assault on the city, hoping to conquer it and win the war; this plan likewise fails.

Brandenburg, Poland and Austria now also join the war against the Swedes.Charles X falls ill in early 1660 and dies in February of that year.

With the death of the Swedish king, one of the major obstacles to peace is gone and the Treaty of Oliva is signed with the Allies (the Poland, Austria and Brandenburg).

However, the Danes are not keen on peace after their recent successes and witnessing the weakness of the Swedish efforts.

The Dutch retrace their blockade, but are soon convinced by the Danes to support them again.

The French and English intervene for the Swedish and the situation is again teetering on the edge of a major conflict.

However, the Danish statesman Hannibal Sehested negotiates a peace treaty without any direct involvement by foreign powers and the conflict is resolved with the Treaty of Copenhagen, where Sweden is forced to return Bornholm to Denmark and Trøndelag to Norway.

The treaty of 1660 establishes political borders between Denmark, Sweden and Norway which have lasted to the present day.