Roman–Parthian War of 58–63

Armenia had been a Roman client state since the days of Emperor Augustus, but in 52/53, the Parthians succeeded in installing their own candidate, Tiridates, on the Armenian throne.

The war, which was the only major foreign campaign of his reign, began with rapid success for the Roman forces, led by the able general Gnaeus Domitius Corbulo.

As soon as these had been dealt with, however, the Parthians turned their attention to Armenia, and after a couple of years of inconclusive campaigning, inflicted a heavy defeat on the Romans in the Battle of Rhandeia.

The conflict ended soon after, in an effective stalemate and a formal compromise: a Parthian prince of the Arsacid line would henceforth sit on the Armenian throne, but his nomination had to be approved by the Roman emperor.

[5] Ever since the expanding Roman Republic and the Parthian Empire had come into contact in the mid-1st century BC, there had been friction between the two great powers of the Near East over the control of the various states lying between them.

[9] Nero reacted vigorously, appointing Gnaeus Domitius Corbulo, a general who had distinguished himself in Germania and now served as governor of Asia, to supreme command in the East.

[12] Initially, the Romans hoped to resolve the situation by diplomatic means: Corbulo and Ummidius Quadratus, the governor of Syria, both sent embassies to Vologases, proposing that he give up hostages, as was customary during negotiations, to ensure good faith.

[15] According to Tacitus, Corbulo discharged all who were old or in ill health, kept the entire army under canvas in the harsh winters of the Anatolian plateau to acclimatize them to the snows of Armenia, and enforced a strict discipline, punishing deserters by death.

He had three legions at his disposal (III Gallica and VI Ferrata from Syria and IV Scythica),[19] to which were added a large number of auxiliaries and allied contingents from Eastern client kings like Aristobulus of Lesser Armenia and Polemon II of Pontus.

The situation was furthermore favorable to the Romans: Vologases faced a serious revolt by the Hyrcanians in the region of the Caspian Sea as well as incursions of Dahae and Sacae nomads from Central Asia, and was unable to support his brother.

Given that Tiridates avoided confrontation in a pitched battle, Corbulo divided his force, so that they could attack several places simultaneously, and instructed his allies, Kings Antiochus IV of Commagene and Pharasmanes I of Iberia, to raid Armenia from their own territories.

[21] Tiridates then resorted to a tactic that had worked well a century earlier against Mark Antony: he sent forces to raid the Roman army's supply route, which stretched over the mountains back to Trapezus in the Black Sea.

Not only were they instrumental in controlling the surrounding country and sources of revenue and soldiers, but in addition, a threat to them might force Tiridates to risk a pitched battle, since, in the words of historian A. Goldsworthy, "a king who could not defend communities loyal to him [...] lost prestige.

"[23] Corbulo and his subordinates successfully stormed three of these forts, including Volandum (possibly modern Iğdır),[24] "the strongest of all in that province" according to Tacitus, within a day with minimal casualties, and massacred their garrisons.

The Roman soldiers were under strict orders not to break formation, and despite repeated probing attacks and feigned retreats by the Parthian horse archers, they held together until nightfall.

[25] During the night, Tiridates withdrew his army, abandoning his capital; its inhabitants promptly surrendered and were allowed to leave unmolested, but the city was torched, since the Romans could not spare sufficient men for garrisoning it.

[27] In the harsh, dry terrain of northern Mesopotamia, the army suffered from lack of provisions, especially water, until they reached the more fertile areas near Tigranocerta.

In order to reinstall his brother on the Armenian throne, the Parthian king assembled a force of picked cavalry under Monaeses, complemented by infantry from Adiabene.

[37] At the same time, however, the Romans also left Armenia, which, according to 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.

[41] Paetus nonetheless appeared confident of victory, and followed the Parthian declaration of war and capture of Tigranocerta with his own invasion of Armenia,[42] while Corbulo remained at Syria, further strengthening the fortifications in the Euphrates frontier.

Paetus sent his wife and son to safety in the fortress of Arsamosata, and tried to block the Parthian advance by occupying the passes of the Taurus mountains with detachments from his army.

[45] Corbulo in the meantime had been aware of the danger faced by his colleague, and put part of his forces on standby, but he did not march to join Paetus, and some accused him of delaying in order to reap more glory from rescuing him.

[47] The subsequent treaty was humiliating: not only would the Romans leave Armenia and surrender all forts they held, but they also agreed to build a bridge over the nearby Arsanias river over which Vologases could pass in triumph, sitting atop an elephant.

[49] The two Roman forces met on the banks of the Euphrates near Melitene, amidst scenes of mutual grief;[50] while Corbulo lamented the undoing of his achievements, Paetus tried to convince him to attempt to reverse the situation by invading Armenia.

Their demands, and the subsequent interrogation of the centurion who accompanied them, revealed to Nero and the Senate the true extent of the disaster, which Paetus had concealed in his dispatches.

[53] Corbulo reordered his forces, withdrawing the defeated and demoralized IV Scythica and XII Fulminata legions to Syria, leaving X Fretensis to guard Cappadocia, and leading his veteran III Gallica and VI Ferrata to Melitene, where the invasion army was to be assembled.

To these he also added V Macedonica, which had remained in Pontus throughout the previous year and not been tainted by the defeat, the newly arrived XV Apollinaris, and large numbers of auxiliaries and contingents of the client kings.

[56] Once there, Corbulo put Paetus' son, who served under him as a legate, in charge of a party that was to gather the remains of the Roman soldiers and ensure them a proper burial.

Tiridates approached the Roman camp, where a statue of the Emperor Nero had been erected upon a raised platform, and placed his royal diadem at its feet in submission.

[68] Direct Roman control was extended to the entire line of the Euphrates, marking the beginning of the Eastern limes that would survive until the Muslim conquests of the 7th century.