Battle of Sankelmark
1864 CE.
Shown on the map at 54.718°, 9.444°.
The Battle of Sankelmark (or Battle of Oeversee) was a minor battle during the Second Schleswig War. It took place on 6 February 1864 between Sankelmark and Oeversee, on the road between Schleswig and Flensburg, during the Danish retreat from the Danevirke.
Text from the Wikipedia article Battle of Sankelmark, licensed CC BY-SA 4.0.