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 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 's invasion and conquest of Armenia Unhappy with the Parthian reconquest of Armenia, in 54 the newly ascended Roman emperor
Nero sent his general,
Corbulo to restore Roman authority in the country. Vologases was unable to aid his brother, due to the rebellion of his son
Vardanes II and subsequently a revolt in the eastern Parthian province of
Hyrcania. Supported by Vologases, Tiridates sent
flying columns to raid the Romans far and wide in 58. Corbulo responded by using the same tactics. He also emboldened the Roman client-kings
Antiochus IV of Commagene, Pharasmanes I, and the
Moschi tribes to attack outlying areas of Armenia. The loyalty of the Armenian population was split up between the Parthians and Romans, although overall they preferred Parthian rule, due to it being more tolerant, and also due to the similarity between Parthian and Armenian culture. Corbulo conquered the Armenian capital of
Artaxata, which he had destroyed. The following year (59) he conquered
Tigranocerta in southern Armenia, where he wintered. Tiridates took advantage of this situation to return to northern Armenia from Atropatene. However, by the spring of 60, he was forced to withdraw by the Roman forces once more. Nero appointed a Cappadocian prince named
Tigranes on the Armenian throne. The new ruler, protected by a strong Roman force, became bold and started in 61 attacking the border areas of
Adiabene, a vassal kingdom of the Parthians. The Adiabenian king,
Monobazos, including Tiridates, protested in front of the entire Parthian court, complaining that Vologases did not do enough to protect his subjects. This situation was important and endangered the relations between Vologases and his subjects. During a public feast, Vologases supported Tiridates' appeals, and placed the royal
diadem on his head. He also appointed a certain nobleman named Monaeses as the commander of a Parthian force that included contingents from Adiabene. Monaeses was sent into Armenia, where he besieged Tigranocerta in 62. The city was strongly fortified, and had been further reinforced by two
legions. The Parthians attempts to scale the city proved fruitless, with the Adiabenian contingents suffering heavy losses. At this point, Corbulo sent an envoy to Vologases, who had encamped with his court at
Nisibis, near Tigranocerta and the Roman–Parthian border. The failed siege and a shortage of fodder for his cavalry forced Vologases to agree to withdraw Monaeses from Armenia. At the same time, however, the Romans also left Armenia, which, according to the contemporary Roman historian
Tacitus, raised suspicions as to Corbulo's motives: some whispered that he had reached an agreement of mutual withdrawal with the Parthians, and that he was unwilling to risk his reputation by renewing hostilities against them. At any rate, a truce was arranged and a Parthian embassy was dispatched to Rome. The negotiations failed to reach an agreement, and war was resumed in the spring of 62. The Roman government then sent
Lucius Caesennius Paetus, governor of Cappadocia, to settle the question by bringing Armenia under direct Roman administration. Paetus was an incapable commander and suffered a humiliating defeat at the
Battle of Rhandeia in 62, losing the legions of
XII Fulminata commanded by Calvisius Sabinus and
IIII Scythica commanded by
Lucius Funisulanus Vettonianus. The command of the troops was returned to Corbulo, who, the following year, led a strong army into
Melitene and beyond into Armenia, eliminating all of the regional governors he suspected were pro-Parthian. Finally in Rhandeia, Corbulo and Tiridates I met to make a peace agreement. The location of Rhandeia suited both Tiridates I and Corbulo. It appealed to Tiridates I because that is where his army had beaten the Romans and sent them away under a capitulation; on the other hand, it appealed to Corbulo because he was about to wipe out the ill repute earned before in the same location. When Tiridates I arrived at the Roman camp he took off his royal diadem and placed it on the ground near a statue of Nero. Tiridates I was recognized as the vassal king of Armenia; a Roman garrison would remain in the country permanently, in Sophene while Artaxata would be reconstructed. Corbulo left his son-in-law
Lucius Annius Vinicianus to accompany Tiridates I to Rome in order to attest his own fidelity to Nero. == Later life and death ==