Battle of Marcellae
756 CE.
Shown on the map at 42.638°, 26.896°.
The Battle of Marcellae (Bulgarian: Битката при Маркели, Greek: Μάχη των Μαρκελλών) took place in 756 between the armies of the First Bulgarian Empire and the Byzantine Empire at Markeli, near the town of Karnobat in south eastern Bulgaria. The result was a Byzantine victory.
Text from the Wikipedia article Battle of Marcellae (756), licensed CC BY-SA 4.0.