Battle of Vindonissa
298 CE.
Shown on the map at 47.467°, 8.217°.
The Battle of Vindonissa was fought in 298 or 302 between the Imperial Roman army, led by Emperor Constantius Chlorus, and the Alemanni. The Romans won the battle, fought in Vindonissa, strengthening Rome's defenses along the Rhine.
Text from the Wikipedia article Battle of Vindonissa, licensed CC BY-SA 4.0.