Battle of Kopidnadon The Battle of Kopidnadon or Kopidnados took place in September 788 between the armies of the Abbasid Caliphate and the Byzantine Empire . The Abbasid army launched an invasion of Byzantine Asia Minor , and was confronted by a Byzantine force at Kopidnadon . The resulting battle was an Abbasid victory . Among the Byzantine losses was a certain Diogenes , who is identified by some scholars with the probable original source for the literary hero Digenes Akritas . Background . Ever since the failure of the last Arab attempt to conquer the Byzantine capital Constantinople , regular , almost annual raids were undertaken by the Caliphate ' s forces into Byzantine Asia Minor . In 782 , a major invasion , led by the Abbasid heir apparent , the future Harun al - Rashid ( r . 786 – 809 ) , resulted in a humiliating settlement for Byzantium , which was forced to sue for a truce in exchange for an annual payment of 160 , 000 gold " nomismata " . In 785 , Empress - regent Irene of Athens resolved to cease the payment of the tribute , and warfare recommenced . The Arabs raided the Armeniac Theme , but in early 786 the Byzantines retaliated by sacking and razing to the ground the fortress town of Hadath in Cilicia , which the Abbasids had spent the last five years turning into a major stronghold and military base for their cross - border expeditions against Byzantium . Battle . With Harun al - Rashid ' s accession in 786 , the raids launched over the next two years were relatively minor affairs ; the first great invasion of the new reign occurred in 788 , when a large expeditionary force crossed the Cilician Gates into the Anatolic Theme . Although the raid is not mentioned in Arabic sources , its description by the Byzantine chronicler Theophanes the Confessor points to a major invasion , as it was confronted by the forces of the two most powerful Byzantine thema tic armies , those of the Anatolic Theme itself and of the Opsician Theme . The site of the battle is called " Kopidnadon " in Theophanes , a name otherwise unattested . Modern scholars , beginning with Henri Grégoire in 1932 , have identified it with the town of Podandos , on the western exit of the Cilician Gates . According to the brief account of Theophanes , the battle ended in a bloody defeat for the Byzantines , who lost many men and officers , including members of the " tagma " of the " Scholai " who had been banished to the provinces by Irene in 786 for their continued support of Iconoclasm . Theophanes also singles out the loss of the capable officer Diogenes , a " tourmarches " ( division commander ) of the Anatolics . Impact . The immediate impact of the Byzantine defeat seems to have been negligible ; losses were heavy but not unbearable , and the level of devastation of the region seems to have been minimal . In material terms , there is therefore little to distinguish the defeat at Kopidnadon from the " typical " Arab raid . It marks , however , a recommencement of large - scale border warfare after the relative lull since 782 , which continued unabated until Harun ' s death in 809 and the subsequent Abbasid civil war . Perhaps the most long - term consequence of the battle was the death of the " tourmarches " Diogenes : by virtue of his unusual prominence in Theophanes ' s account , Henri Grégoire identified this Diogenes with the original archetype for the later epic hero Digenes Akritas .