Battle of Anzen: The Byzantine emperor Theophilos suffers a heavy defeat by the Abbasids.
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 huge 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 fierce counterattack by Afshin's Turkish horse-archers, the Byzantine army broke and fled. Theophilos and his guard were besieged for a while on a hill, before making good their escape. The defeat opened the way for the brutal sack of Amorion a few weeks later, one of the most serious blows Byzantium suffered in the centuries-long Arab–Byzantine Wars.