Battle of Bomarsund
1854 CE.
Shown on the map at 60.212°, 20.238°.
The Battle of Bomarsund, in August 1854, took place during the Åland War, which was part of the Crimean War, when an Anglo-French expeditionary force besieged, captured, and subsequently destroyed a Russian fortress. It was the only major action of the war to take place at Bomarsund in the Baltic Sea.
Text from the Wikipedia article Battle of Bomarsund, licensed CC BY-SA 4.0.