The Dutch rescue the Danes from the Swedes:

"The naval Battle of the Sound took place on 8 November 1658 (29 October O.S.) during the Second Northern War, near the Sound or Oresund, just north of the Danish capital, Copenhagen. Sweden had defeated Denmark and an army under Charles X of Sweden had Copenhagen itself under siege. The Dutch fleet was sent to prevent Sweden from gaining control of both sides of the Sound and thereby controlling access to the Baltic Sea as well as of its trade.

The Dutch, under the command of Lieutenant-Admiral Jacob van Wassenaer Obdam with Egbert Bartholomeusz Kortenaer as his flag captain, who had sailed to the Baltic in support of Denmark, had 41 ships with 1413 guns while the Swedes, under Lord High Admiral Carl Gustaf Wrangel, had 45 ships with 1838 guns. The Dutch were grouped into three squadrons, while the Swedes separated their ships into four. The seven Danish ships with about 280 guns were unable to assist their Dutch allies because of adverse northern winds and could only watch. Obdam, who first received very complicated written instructions from the Grand Pensionary, Johan de Witt, and went so far as to request them again "in three words", summed up his mission in a single sentence: "Save Copenhagen and punch anyone in the face who tries to prevent it". This was a direct reference to the English, whose powerful fleet had recently defeated the Dutch in the First Anglo-Dutch War; in the event, however, the English did not intervene. The Swedes attacked aggressively, but failed to gain the upper hand, primarily due to the fact that the approaching Dutch had the weather gage. The Dutch forced the Swedish fleet to end the blockade of the Danish capital, enabling it's resupply by Dutch armed transport ships, which eventually forced Charles to abandon the siege entirely.

The Swedes lost five ships in the action compared to one Dutch ship, however, remaining allied ships were more damaged. Also, considering the slightly fewer losses of men in the Swedish army; 1,200 compared to 1,400 (439 killed, 269 captured and slightly more than 650 wounded allies), the battle is considered a tactical draw. Strategically, however, it was a major allied victory."

Taken from: http://en.wikipedia.org/wiki/Battle_of_the_Sound

Eric