"Vologases III (Parthian: 𐭅𐭋𐭂𐭔 Walagash) was king of the Parthian Empire from 110 to 147. He was the son and successor of Pacorus II (r. 78–110).
Vologases III's ...
reign was marked by civil strife and warfare. At his ascension, he had to deal with the usurper Osroes I (r. 109–129), who managed to seize the western part of the empire, which left Vologases III in control of its eastern parts. After Osroes I violated the Treaty of Rhandeia with the Romans by appointing Parthamasiris as the king of Armenia in 113, the Roman emperor Trajan (r. 98–117) invaded the Parthian lands, briefly seizing the Parthian cities of Seleucia and Ctesiphon and reaching as far as the Persian Gulf. These gains were short-lived; all the Roman gains had been lost after Trajan's death in 117. Vologases III, whose eastern domains were untouched, took advantage of the weakened state of Osroes I to regain lost territory, and finally defeated him in 129. Another contender named Mithridates V shortly appeared afterwards, but was also defeated by Vologases III, in 140." - (en.wikipedia.org 11.08.2021)
