Battle of the Arar
57 BCE.
Shown on the map at 45.727°, 4.818°.
The Battle of the Arar was fought between the migrating tribes of the Helvetii and six Roman legions under the command of Gaius Julius Caesar in 58 BC. It was the first major battle of the Gallic Wars and ended in a tactical victory for the outnumbered Roman army.
Text from the Wikipedia article Battle of the Arar, licensed CC BY-SA 4.0.