Battle of Byzantium
316 BCE.
Shown on the map at 40.200°, 26.400°.
The Battle of Byzantium (Byzantion) was a 317 BC engagement between the generals Antigonus Monopthalmus and Cleitus the White, during the Second War of the Diadochi. Fought over the course of two days, near Byzantium at the Hellespont, it resulted in a stunning Antigonid victory.
Text from the Wikipedia article Battle of Byzantium, licensed CC BY-SA 4.0.