In the age-old war between the Byzantines and Persians and because of its strategic position, Callinicus was fortified by the Byzantine emperor Leo I 457 475, who changed its name to Leontopolis. About sixty years later 531, the Byzantine armies led by Belisarius were defeated on the plain of Callinicus by the Persians, who razed the city to the ground in 542. The clashes between Byzantines and Persians continued even after the truce concluded between Justinian and Chosroes 545; only a few years later Callinicus was the theater of another battle between the two armies 583. Congo, Democratic Republic Map With the Arab invasion of 639 the city changed the ancient name to Raqqa. By the will of the emperor and for the purpose of settling the disputes between Chalcedonian Christians and monophysites, in 567 the city hosted a meeting of bishops of the two groups, which resolved absolutely nothing. At this time there were numerous recluses living near the city; also nearby was the Monastery of Mar Mattai, famous for theological studies. In his chronicle the historian Michael the Syrian reports the names of 20 monophysite bishops who succeeded one another at Callinicus from the mid-8th to the end of the 12th c. DHGE 11, 412-414; R. Mouterde – A. Poidebard, Le limes de Chalcis, I, Paris 1945, 127-129; R. Devreesse, Le patriarcat d’Antioche depuis la paix de l’‰glise jusqu’ la conquªte arabe, Paris 1945, 295; L. Padovese, Guida alla Siria, Casale Monf. 1994, 61-63; M. Al-Khalaf – K. Kohlmeyer, Untersuchungen zu ar-Raqqa – Nikephorion Callinicum: Mitt. des deutschen arch¤ol. Instituts, Damaskus 2 1985 133-162; H. Savon, Ambroise de Milan, Paris 1997, 251-264; Fedalto 2, 809.