Battle of Anchialus
763 CE.
Shown on the map at 42.550°, 27.650°.
The battle of Anchialus (Bulgarian: Битката при Анхиало) occurred in 763, near the town of Pomorie on the Bulgarian Black Sea Coast. The result was a Byzantine victory.
Text from the Wikipedia article Battle of Anchialus (763), licensed CC BY-SA 4.0.