Editing Constantine V (section)

=== Campaigns against the Arabs ===
{{Further|Byzantine–Arab wars (780–1180)|Arab–Byzantine wars#Stabilization of the frontier, 718–863}}
In 746, profiting by the [[Third Fitna|unstable conditions]] in the Umayyad Caliphate, which was falling apart under [[Marwan II]], Constantine invaded Syria, captured [[Kahramanmaraş|Germanikeia]] (his father's birthplace) and recaptured the island of [[Cyprus]]. He organised the resettlement of part of the local Christian population to imperial territory in [[Thrace]], strengthening the empire's control of this region. In 747 his fleet destroyed the Arab fleet off Cyprus. The same year saw a serious outbreak of plague in Constantinople, which caused a pause in Byzantine military operations. Constantine retired to [[Bithynia]] to avoid the disease and, after it had run its course, resettled people from mainland Greece and the Aegean islands in Constantinople to replace those who had perished.<ref>Treadgold (1997), pp. 359–360</ref>

In 751 he led an invasion into the new [[Abbasid Caliphate]] under [[As-Saffah]]. Constantine captured  [[Erzurum|Theodosiopolis]] and [[Malatya|Melitene]], which he demolished, and again resettled some of the population in the [[Balkans]]. The eastern campaigns failed to secure concrete territorial gains, as there was no serious attempt to retain control of the captured cities, except [[Camachus|Camachum]] (modern [[Kemah, Erzincan|Kemah]]), which was garrisoned. However, under Constantine the Empire had gone on the offensive against the Arabs after over a century of largely defensive warfare. Constantine's major goal in his eastern campaigns seems to have been to forcibly gather up local Christian populations from beyond his borders in order to resettle Thrace. Additionally, the deliberate depopulation of the region beyond the eastern borders created a no-man's land where the concentration and provisioning of Arab armies was made more difficult. This in turn increased the security of Byzantine Anatolia. His military reputation was such that, in 757, the mere rumour of his presence caused an Arab army to retreat. In the same year he agreed a truce and an exchange of prisoners with the Arabs, freeing his army for offensive campaigning in the Balkans.<ref>Bury, p. 10</ref><ref>Ostrogorsky, p. 167</ref><ref>Treadgold (1997), pp. 360, 362</ref><ref>Bonner, p. 107</ref>