Battle of Gumbinnen
1914 CE.
Shown on the map at 54.600°, 22.200°.
The Battle of Gumbinnen, initiated by forces of the German Empire on 20 August 1914, was a German offensive on the Eastern Front during the First World War. Because of the hastiness of the German attack, the Russian Army emerged victorious.
Text from the Wikipedia article Battle of Gumbinnen, licensed CC BY-SA 4.0.