Siege of Autun
356 CE.
Shown on the map at 46.950°, 4.300°.
The siege of Autun was a conflict fought between the Roman Empire and the invading barbarian Alamanni tribe, who were ravaging Gaul, in 356 AD. The Romans successfully defended the city, and the barbarians retreated on the approach of reinforcements.
Text from the Wikipedia article Siege of Autun (356), licensed CC BY-SA 4.0.