1911 Encyclopædia Britannica/Osroes
OSROES (also Osdroes or Chosroes), the Greek form of the Persian name Khosrau (see Chosroes). The form Osroes is generally used for a Parthian king who from his coins appears to have reigned from about A.D. 106–129, as successor of his brother Pacorus. But during all this time another king, Vologaeses II. (77–147) maintained himself in a part of the kingdom. Osroes occupied Armenia, and placed Exedares, a son of Pacorus, and afterwards his brother Parthamasiris on the throne. This encroachment on the Roman sphere led to the Parthian war of Trajan. In 114 Parthamasiris surrendered to Trajan and was killed. In Mesopotamia a brother of Osroes, Meherdates (Mithradates IV.), and his son Sanatruces II. took the diadem and tried to withstand the Romans. Against them Trajan united with Parthamaspates, whom he placed on the throne, when he had advanced to Ctesiphon (116). But after the death of Trajan (117) Hadrian acknowledged Osroes and made Parthamaspates king of Edessa (Osroene); he also gave back to Osroes his daughter who had been taken prisoner by Trajan (Dio Cass. 68, 17, 22. 33, Malalas, p. 270 ff.; Spartian, Vita Hadr. 5. 13; Pausan. v. 12, 6). But meanwhile Vologaeses II. had regained a dominant position; his coins begin again in 122 and go on to 146, whereas after 121 we have no coins of Osroes except in 128.
By Procopius, Pers. i. 17, 24, the name of the territory of Osroene is derived from a dynast Osroes, but this is a false etymology (see Osroene). (Ed. M.)