Battle of Prinitza
1263 CE.
Shown on the map at 37.670°, 21.500°.
The Battle of Prinitza was fought in 1263 between the forces of the Byzantine Empire, marching to capture Andravida, the capital of the Latin Principality of Achaea, and a small Achaean force. The Achaeans launched a surprise attack on the greatly superior and overconfident Byzantine force, defeated and scattered it, saving the principality from conquest.
Text from the Wikipedia article Battle of Prinitza, licensed CC BY-SA 4.0.