Battle of the Rishki Pass
759 CE.
Shown on the map at 42.937°, 26.939°.
The Battle of the Rishki Pass (Bulgarian: Битката при Ришкия проход) or Battle of Veregava took place in the pass of the same name, in Stara Planina, Bulgaria in 759. It was fought between the Bulgarian Empire and the Byzantine Empire. The result was a Bulgarian victory.
Text from the Wikipedia article Battle of the Rishki Pass, licensed CC BY-SA 4.0.