Turkey / Byzantium: Leo III (685-741) and Constantine V (718-775); Byzantine emperors; from the book Icones imperatorvm romanorvm (Icons of Roman Emperors); Antwerp; c. 1645. Leo III served under Emperor Justinian II when the emperor was attempting to reclaim his throne. After Justinian's victory; Leo was sent to fight against the Umayyad Caliphate; and was appointed as overall commander by Emperor Anastasius II. Leo became ambitious; and he conspired to overthrow the new Emperor Theodosius III. Entering Constantinople in 717 he forced Theodosius to abdicate. He was succeeded by his son and heir; Constantine V; also known as Constantine the Dung-named.