Vologases I ( Walagash) was the King of Kings of the Parthian Empire from 51 to 78. He was the son and successor of Vonones II (r. 51). He was succeeded by his younger son Pacorus II, who continued his policies. Name Vologases is the Greek and Latin form of the Parthian Walagaš (). The name is also attested in New Persian as Balāsh and Middle Persian as Wardākhsh (also spelled Walākhsh). The etymology of the name is unclear, although Ferdinand Justi proposes that Walagaš, the first form of the name, is a compound of words "strength" (varəda), and "handsome" (gaš or geš in Modern Persian). Background Vologases was a son of Vonones II, a Parthian prince who ruled the northern Iranian kingdom of Media Atropatene, and possibly subsequently the whole Parthian Empire for a few months. Vologases' mother was a Greek concubine of the Parthian harem. The name of the Arsacid branch established by Vologases I has been coined by the modern historian Marek Jan Olbrycht as the "Vologasids" or the "House of Vologases I", which ruled the Parthian Empire from 51 till its fall in 224. Reign Invasion of Armenia Vologases became the new Parthian king in 51. He sought to continue the policies of the prominent former Parthian king Artabanus II (), and thus, one of his first objectives was to strengthen and bolster the Parthian position in strategically and politically unstable regions which had served for decades as the source of war with the Romans. He gave the kingship of Media Atropatene to his elder brother Pacorus, while the even more politically important kingship of Armenia was given to Vologases' younger brother Tiridates after a Parthian invasion of the country in 53. Vologases felt his invasion was justified due to the recent usurpation of the Armenian throne by the Iberian prince Rhadamistus, which he saw as a violation of the former settlement made between the Parthians and Romans regarding Armenia. Lack of resources and a winter epidemic forced Vologases to withdraw his troops from Armenia, allowing Rhadamistus to come back and punish locals as traitors; they shortly revolted and helped Tiridates restore his authority. Rhadamistus himself returned to Iberia and was soon put to death by his father Pharasmanes I for having plotted against the royal power in order to prove his loyalty to Rome. War with the Romans Unhappy with the Parthian reconquest of Armenia,