 The defeat and captivity of emperor Valerian at the hands of the Persian Sassanian monarch Shapur I in 260 left the eastern Roman provinces largely at the mercy of the Persians . Odaenathus stayed on the side of Rome ; assuming the title of king , he led the Palmyrene army and fell upon the Persians before they could cross the Euphrates to the eastern bank , and inflicted upon them a considerable defeat . Then , Odaenathus took the side of emperor Gallienus , the son and successor of Valerian , who was facing the <unk> of Fulvius Macrianus . The rebel declared his sons emperors , leaving one in Syria and taking the other with him to Europe . Odaenathus attacked the remaining <unk> and <unk> the rebellion . He was rewarded many exceptional titles by the emperor who formalized his self @-@ established position in the East . In reality , the emperor could have done little but to accept the declared nominal loyalty of Odaenathus . 
