Battle of Adrianople
1254 CE.
Shown on the map at 41.667°, 26.567°.
The Battle of Adrianople was fought in 1254 between the Byzantine Greek Empire of Nicaea and the Second Bulgarian Empire. Michael Asen I of Bulgaria attempted to conquer land taken by the Empire of Nicaea, but the advance of Theodore II Lascaris caught the Bulgarians unprepared. The Byzantines were victorious.
Text from the Wikipedia article Battle of Adrianople (1254), licensed CC BY-SA 4.0.