Constantine V was Byzantine emperor from 741 to 775. His reign saw a consolidation of Byzantine security from external threats. As an able military leader, Constantine took advantage of civil war in the Muslim world to make limited offensives on the Arab frontier. With this eastern frontier secure, he undertook repeated campaigns against the Bulgars in the Balkans. His military activity, and policy of settling Christian populations from the Arab frontier in Thrace, made Byzantium's hold on its Balkan territories more secure. He was also responsible for important military and administrative innovations and reforms. 718 – September 18, 775; died at about 57. Alive at the same time as Li Bai, Abū Ḥanīfa, Charlemagne, Abu Nuwas, and Du Fu. Wiki link