Battle of Hafrsfjord
872 CE.
Shown on the map at 58.941°, 5.671°.
The Battle of Hafrsfjord (Norwegian: Slaget i Hafrsfjord) was a naval battle fought in Hafrsfjord sometime between 872 and 900 that resulted in the unification of Norway, later known as the Kingdom of Norway. After the battle, the victorious Viking chief Harald Fairhair proclaimed himself the first king of the Norwegians, merging several petty kingdoms under a single monarch for the first time.
Text from the Wikipedia article Battle of Hafrsfjord, licensed CC BY-SA 4.0.