Battle of Lyrskov Heath
1043 CE.
Shown on the map at 54.550°, 9.467°.
The Battle of Lyrskov Heath (or Hede) was fought on September 28, 1043, at Lyrskov, between a Dano-Norwegian army led by Magnus the Good and an army of Wends. It was a great victory for Magnus' forces; the Wendish army was crushed and up to 15,000 were killed. Lyrskov (German: Lürschau) is today the name of a German municipality in the Schleswig-Flensburg district, and of a small town northwest of Schleswig in the same municipality.
Text from the Wikipedia article Battle of Lyrskov Heath, licensed CC BY-SA 4.0.