Battle of Bathys Ryax The Battle of Bathys Ryax was fought in 872 or 878 between the Byzantine Empire and the Paulicians . The Paulicians were a Christian sect which — persecuted by the Byzantine state — had established a separate principality at Tephrike on Byzantium ' s eastern border and collaborated with the Muslim emirates of the " Thughur " , the Abbasid Caliphate ' s borderlands , against the Empire . The battle was a decisive Byzantine victory , resulting in the rout of the Paulician army and the death of its leader , Chrysocheir . This event destroyed the power of the Paulician state and removed a major threat to Byzantium , heralding the fall of Tephrike itself and the annexation of the Paulician principality shortly after . Background . The Paulicians were a Christian sect whose precise origins and beliefs are somewhat obscure : Byzantine sources portray them as dualists , while Armenian sources maintain that they were an adoptionist sect . The Paulicians were fiercely iconoclastic , adhered to a very distinct Christology and rejected the authority and practices of the official Byzantine Church , following their own leaders . Consequently , they were persecuted by the Byzantine state as early as 813 , despite the emperors ' official support for iconoclasm . After the definitive end of Byzantine Iconoclasm in 843 , that persecution was intensified : in an attempt , unique in Byzantine history , to eradicate an entire " heretical " sect , orders were sent out to kill anyone who would not recant . According to the chroniclers , up to 100 , 000 Paulicians were massacred , while the remnants fled from their strongholds in east - central Anatolia , and found refuge among the Empire ' s Muslim enemies , the Arab emirates of the " Thughur " , the Arab – Byzantine frontier zone along the Taurus – Antitaurus mountain ranges . With support from the emir of Melitene , Umar al - Aqta , the Paulician leader Karbeas founded a separate principality at Tephrike , and for the next decades , the Paulicians campaigned alongside the Arabs against Byzantium . The Arabs and Paulicians suffered a critical blow in 863 with the defeat and death of Umar at the Battle of Lalakaon and the death of Karbeas in the same year , but under their new leader , Chrysocheir , the Paulicians resumed their raids deep into Byzantine Anatolia , raiding as far as Nicaea and sacking Ephesus in 869 / 970 . The new Byzantine emperor , Basil I the Macedonian ( r . 867 – 886 ) , sent an embassy for negotiations to Tephrike . After the talks failed , Basil led a campaign against the Paulician state in the spring of 871 , but was defeated and only narrowly managed to escape himself . Battle . Encouraged by this success , Chrysocheir then staged another deep raid into Anatolia , reaching Ancyra and ravaging southern Galatia . Basil reacted by sending his relative , the Domestic of the Schools Christopher , against them . The Paulicians managed to avoid a clash , and as the campaigning season drew to a close , they began retiring towards their own territory . They encamped at Agranai ( modern Muşalem Kalesı ) in the theme of Charsianon , with the shadowing Byzantine army making their camp at nearby Siboron ( Σίβορον , modern Karamadara ) to the west . From there , the Paulicians marched northeast to the pass of Bathys Ryax or Bathyryax ( Βαθυρύαξ , " Deep Stream " , modern Kalınırmak pass west of Sivas in Turkey ) , a location of strategic importance , as indicated by the fact that it served as a fortified assembly point ( " aplekton " ) for Byzantine expeditions to the East . Christopher sent the " strategoi " of the themes of Armeniakon and Charsianon ahead with some four to five thousand men , to make contact with the Paulician army , shadow it as far as the pass and report on its intentions , i . e . whether it intended to double back westwards to resume raiding Byzantine territory or whether it headed back to Tephrike , in which case they would have to rejoin the Domestic ' s forces . When the two generals with their men reached the pass , night had fallen , and the Paulicians , apparently unaware that they were being followed , had made camp in the valley of the pass . The Byzantines took up position in a wooded hill called Zogoloenos that overlooked the Paulician encampment , which further concealed them from their enemy . At this point , the sources record that a dispute broke out between the men of the two thematic corps as to who was the bravest ; the two generals decided to take advantage of their troops ' high morale and impetuousness to attack , despite their orders . A picked detachment of 600 men from both divisions launched a surprise attack at dawn , while the rest of the army remained behind and made loud clamour with trumpets and drums , so as to suggest the imminent arrival of the entire Byzantine field army under Christopher . The ruse worked perfectly : the Paulicians , taken by surprise , panicked and dispersed without offering any serious resistance . The Paulician rout was completed as they fell upon the main Byzantine army while fleeing . Their remnants were pursued by the victorious Byzantines up to a distance of 50 km . Chrysocheir himself managed to escape with a small detachment of bodyguards , but he was brought at bay at Konstantinou Bounos ( probably modern Yildiz Dagı ) . In the ensuing engagement , he was wounded by Poulades , a Byzantine soldier who had been formerly a captive of the Paulicians , and fell from his horse . He was then captured and beheaded by the advancing Byzantines , and his head was sent to Emperor Basil in Constantinople . Aftermath . The defeat at Bathys Ryax signalled the end of the Paulicians as a military power and a threat to Byzantium . Basil followed this success by a series of campaigns in the East against the Paulician strongholds and the Arab emirates . Tephrike itself was taken in 878 and razed to the ground . The remaining Paulicians were resettled in the Balkans , while a large contingent was shipped off to Southern Italy to fight for the Empire under Nikephoros Phokas the Elder . Questions of chronology . The chronology and sequence of events regarding the battle and the fall of the Paulician state is unclear , since the Byzantine sources are contradictory : a number of scholars place the battle in 872 , others in 878 , in both cases either before or after the capture and razing of Tephrike itself by the Byzantines . Thus Alexander Vasiliev proposed a first victorious battle for the Byzantines , followed by the sack of Tephrike and the final Paulician defeat at Bathys Ryax , all in 872 . Most recent historians place the battle before the sack of the city , but disagree in the dates of the two events . Some , like Nina Garsoïan or John Haldon , place both events in 878 ; the French Byzantinist Paul Lemerle , followed by other scholars like Mark Whittow and Warren Treadgold , placed the battle in 872 and the final subjugation of Tephrike years later , in 878 ( Treadgold in 879 ) .