Battle of Anzen
838 CE.
Shown on the map at 40.390°, 36.090°.
The Battle of Anzen or Dazimon was fought on 22 July 838 at Anzen or Dazimon (now Dazmana (Akçatarla), Turkey) between the Byzantine Empire and the forces of the Abbasid Caliphate. The Abbasids had launched a massive expedition with two separate armies in retaliation for the Byzantine emperor Theophilos's successes the previous year, and aimed to sack Amorion, one of Byzantium's largest cities. Theophilos with his army confronted the smaller Muslim army, under the Iranian vassal prince Afshin, at Dazimon. The numerically superior Byzantine army was initially successful, but when Theophilos resolved to lead an attack in person, his absence from his usual post caused panic among the Byzantine troops, who feared that he had been killed. Coupled with a counterattack by Afshin's Turkish horse-archers, the Byzantine army broke and fled. Theophilos and his guard were surrounded on a hill, but managed to escape. The defeat opened the way for the sack of Amorion a few weeks later, one of the most serious blows Byzantium suffered in the centuries-long Arab–Byzantine wars.
Text from the Wikipedia article Battle of Anzen, licensed CC BY-SA 4.0.