Battle of Grathe Heath
1157 CE.
Shown on the map at 56.239°, 9.290°.
The Battle of Grathe Heath was fought in 1157 between the Danish armies of Valdemar I and his rival for the Danish throne, Sweyn III. Valdemar's forces won the battle, and Sweyn III was slain while attempting to flee.
Text from the Wikipedia article Battle of Grathe Heath, licensed CC BY-SA 4.0.