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.

An ambitious man and a convinced iconoclast, Theophilos sought to bolster his regime and gain support for his religious policies by military success against the Abbasid Caliphate, Byzantium's major antagonist.

The latter was probably the largest city in Anatolia at the time, as well as the birthplace of the reigning Amorian dynasty and consequently of particular symbolic importance; according to the chronicles, al-Mu'tasim's soldiers painted the word "Amorion" on their shields and banners.

[2][6][8] Afshin's force included, according to John Skylitzes, the entire army of the vassal Armenian princes, and numbered an estimated 20,000 (Haldon) to 30,000 men (Treadgold), among whom were some 10,000 Turkish horse-archers.

His army included the men from the Anatolian and possibly also the European themes, the elite tagmata regiments, as well as a contingent of Persian and Kurdish Khurramites.

Under their leader Nasr (converted to Christianity and baptized as Theophobos), these people had fled religious persecution in the caliphate, deserted to the empire in the previous years, and formed the so-called "Persian tourma".

[1][2] In mid-June, Afshin crossed the Anti-Taurus Mountains and encamped at the fort of Dazimon (Greek: Δαζιμῶν, modern Dazmana), between Amaseia and Tokat, a strategically important location which served as a concentration point (aplekton) for the Byzantines.

Near noon, Theophilos resolved to reinforce the other wing and detached 2,000 Byzantines and the Kurdish contingent to do so, abandoning his post and passing behind his own army's lines.

[3][10] At this point, however, Afshin launched his Turkish horse-archers in a counter-attack which halted the Byzantine advance and allowed the Arab forces to regroup.

The Arabs proceeded to surround the hill, but the Byzantines were saved by a sudden rain, which loosened the strings of the Turkish bows, rendering them useless.

[14][13] Though initially appearing decisive, the defeat at Anzen and the subsequent sack of Amorion were militarily of no long-term importance to the Byzantine Empire, since the Abbasids failed to follow up on their success.

It is also remarkable for being the first confrontation of the middle Byzantine army with the Turkic nomads from Central Asia, whose descendants, the Seljuq Turks, would emerge as Byzantium's major antagonists from the mid-11th century on.