The Treaty of Roskilde, signed in February 1658, heralded the end of Swedish King Charles X Gustav’s first Danish war. The king, however, was not satisfied. He wanted to crush Denmark and expand the Swedish empire with its neighbouring country to the west. The king’s second war against Denmark began in August of that year. Kronborg Castle in Helsingør was captured and the Swedes began to besiege Copenhagen.
The Swedes were expanding and planned to take control of the Danish sound Oresund, the strait that separates Denmark from Sweden. This worried the Dutch, prompting them to send a large Dutch fleet to anchor up at the lightship station Lappen in October 1658, north of Kronborg Castle. The Swedes were aware of the Dutch fleet’s presence, but over the course of several days had been able to mobilise an equivalent fleet under the command of Carl Gustav Wrangel, who would prevent the Dutch ships from freeing Kronborg and Copenhagen.
On 29 October, the Dutch fleet eased its anchors and sailed into the Sound. To avoid fire from the cannons at Kronborg Castle, the Dutch ships sailed near the Swedish coast. Shortly afterwards, a number of fierce duels were fought among the largest and strongest ships. Admiral Wrangel’s ship, the Victoria, was blown apart by the Dutch ships Brederode and Eendracht and forced to withdraw from the fray. The Swedish ship Draken, together with some other Swedish ships, then managed to sink the Brederode. The Swedish ships Morgonstjerna and Leopard went down, and the Dutch came closer to Copenhagen.
After 7 or 8 hours of persistent fighting, the Swedes could not keep up and instead retreated to Landskrona harbour. The Dutch thus succeeded in rescuing the Danish capital.
The outcome of the Battle of the Sound was considered a major loss for Sweden. One of the consequences was that Charles X Gustav was forced to relinquish the idea of incorporating Denmark into the Swedish Empire.