Battle of Nicaea
193 CE.
Shown on the map at 40.429°, 29.719°.
The Battle of Nicaea was fought in 193 between the forces of Septimius Severus and his eastern rival, Pescennius Niger. It took place at Nicaea in Asia Minor. Severus defeated his rival, and ended his bid for the Roman Empire the next year at Issus.
Text from the Wikipedia article Battle of Nicaea, licensed CC BY-SA 4.0.