Battle of Thermopylae 279 BCE
278 BCE.
Shown on the map at 38.805°, 22.563°.
The Battle of Thermopylae was fought in 279 BC between invading Gallic armies and a combined Greek army of Aetolians, Boeotians, Athenians, Phocians and Locrians at Thermopylae. The Gauls under Brennus were victorious, and advanced further into the Greek peninsula where they attempted to sack Delphi but were completely defeated.
Text from the Wikipedia article Battle of Thermopylae (279 BC), licensed CC BY-SA 4.0.