Battle of Marcellae The Battle of Marcellae ( , ) took place in 792 at Markeli , near the modern town of Karnobat in south eastern Bulgaria . It is not to be confused with the earlier battle at the same place . Prelude . In the eith quarter of the 8th century Bulgaria overcame the internal political crisis after the end of the rule of the Dulo . The khans Telerig and Kardam managed to consolidate the central authority and put an end of the quarrels among the nobility . The Bulgarians finally had the opportunity to intensify their campaigns in Macedonia and annex the region and its Slavic population to their state . In 789 they penetrated deep into the valley of the Struma river and heavily defeated the Byzantines , killing the " strategos " of Thrace Filites . In order to distract the Bulgarian attention from Macedonia , the Byzantine emperor Constantine VI started a campaign in northern Thrace in April 791 . The armies met near the fortress of Provat ( 20 km east of Odrin ) and the Byzantines were forced to retreat but their defeat was not decisive and in the following year the campaign was renewed . Battle . In the summer of the next year Constantine VI led his army north and on 20 July was confronted by the Bulgarians under Kardam near the border castle Marcelae . The Bulgarians had built ramparts blocking the roads to the Rish Pass and the capital Pliska . For several days the emperor did not dare to attack but by the end of July he was convinced by " false astrologists " ( according to the Byzantine chronicler Theophanes the Confessor ) that the stars boded victory and attacked . Before the beginning of the battle , while awaiting the Byzantine assault , the Bulgarian ruler secretly placed part of his cavalry behind the hills surrounding the battlefield . Due to the rugged terrain the advancing Byzantine army broke its order . Taking advantage of that mistake , Kardam ordered a counterattack which brought the Bulgarians a great success . The Bulgarian cavalry went round the Byzantines and cut their way back to their fortified camp and the fortress of Marcellae . The Bulgarians took the supplies , the treasury and the tent of the emperor . Thet chased Constantine VI to Constantinople killing a great number of soldiers . Many Byzantine commanders and officers perished in the battle . A weapon called " arkani " was used by the Bulgarians in this battle : the " arkani " consisted of a long pole with an attachment similar to a lasso at one end . It was an excellent weapon against cavalry as the rider could easily be pulled out of the saddle by a skilled warrior , armed with the " arkani " . Aftermath . After the defeat Constantine VI had to conclude peace with Kardam and had to pay tribute . Four years later ( in 796 ) the emperor stopped the paying leading to a new war in Thrace which ended without a decisive battle . The hostilities between Bulgaria and Byzantium continued under Kardam ' s successor Krum . The victory had great political significance . The decades of crisis were finally overcome , the Byzantines were forced once again to pay tribute to the Khans . Bulgaria entered the 9th century consolidated , stronger and united which was an important factor for the string of victories scored by Krum against the Byzantines .