The battle of Femern was a naval victory for the Danes in the later phase of the Great Northern War (1700-1721). In April 1715 a Swedish fleet under Schoutbynacht Wachtmeister had been sent into the western Baltic, where it had raided Femern and captured a Danish frigate. Wachtmeister had a fleet of six ships – four battleships and two frigates and was expecting reinforcements.
The Danes responded by dispatching a larger fleet under Schoutbynacht Gabel to find and defeat the Swedes. Gabel had eleven warships, including eight battleships with fifty guns or more. The two fleets came together early on 24 April, east of the island of Femern. The Swedes were about seven miles north of the Danes.
Despite being outnumbered by two to one, Wachtmeister was willing to risk a battle. During the morning of 24 April there was little or no wind, but a breeze came up at about noon, and the battle began at four in the afternoon. The Swedes made two attempts to break the Danish line, failing both times. During the second attempt the Swedish ship Södermanland was badly damaged, loosing her captain and pulled out of the battle.
The battle had been inconclusive, but the aftermath handed the victory to the Danes. Overnight the two fleets were anchored between the islands of Femern and Langeland. During the night the Swedish fleet slipped away, and attempted to escape into the Great Belt, but was forced instead to turn south and run towards Kiel. At the mouth of the Kiel Fjord the Swedish fleet ran aground, possibly deliberately. Efforts began to make the ships unusable.
Before they could complete the job they were discovered by two of the Danish ships and forced to surrender. All but one of the Swedish ships were repaired and entered Danish service. Close to 2,000 Swedish sailors were taken prisoner. The total destruction of the Swedish fleet in the western Baltic allowed Gabel to disperse his fleet. The repaired Swedish ships were sent to Copenhagen. Three of his battleships were sent to support the main allied fleet in the Baltic, under Admiral Raben. Finally, Gabel with the rest of his fleet sailed north to blockage the important Swedish port of Gothenburg, from where Swedish fleets had been able to disrupt communications between Denmark and Norway.