The Parthian Empire vs the Roman Empire: 160s CE

“The Parthians alone of mankind have sustained against the Roman people the role of enemy…” This was the assessment of Marcus Cornelius Fronto, the tutor and famous correspondent of the emperors Marcus Aurelius and Lucius Verus. A grammarian, rhetorician, and writer, the above assessment of the Parthian Empire is taken from the preamble to a now-lost history (the principia historia). The piece was, it appears, considered by contemporaries to have been not much more than a puff-piece in praise of the emperor Lucius Verus and more worthy of ridicule than celebration.

However, its subject was much more serious. Fronto’s history was going to be an account of a great war between the Roman and Parthian Empires. In the mid-second century CE, the two vast states had clashed once more. The two vast, dominant powers in the ancient Mediterranean world had fought previously throughout the centuries as they vied for dominance and influence in the Near East and beyond.

In Book 1 of Virgil’s Aeneid — a poem inflated with pro-Augustan propaganda — Jupiter, the lord of the gods, foretells of the Roman Empire’s greatness: “to them, I have given empire without end”. As much as Augustus may have liked to imagine this was true, it seems that Rome’s first emperor was acutely aware of the limits of his empire. In the east, the Parthian Empire had long acted as a counterbalance to Rome’s imperial pretensions. At its greatest extent, the Parthian Empire had stretched from the Euphrates River’s northern banks in central Turkey to the western edges of Afghanistan and Pakistan.

It was also responsible for some of Rome’s most chastening defeats. Crassus, triumvir with Pompey and Caesar, suffered death and ignominy in waging war against the Parthians. Defeated in battle in 53 BCE, Crassus’ army was crushed and their standards snatched; it was a defeat which shamed the Roman military. Caesar was assassinated before he could mount a retaliation, and Mark Antony’s own efforts at restoring Roman pride ended in a harried retreat from Parthian territory. In fact, some semblance of pride was not restored until Augustus’ own reign, when a diplomatic — rather than military success — led to the return of the lost Parthian standards. Symbols of his imperial reach, they were displayed in the Temple of Mars Ultor (Avenging Mars) in the new Forum of Augustus.

2. Origins: Antoninus Pius and the Loss of Armenia

The diplomatic successes of Augustus helped ensure a cessation of direct violence between the two great empires of the ancient Mediterranean world for several decades. Where conflict did arise, it was typically over the question of primacy in one of the proxy states that the empires both sought to control. Armenia was often a point of tension, and the question of control over this buffer state led to war in 58 CE during the reign of Nero. The war ended in something of a stalemate in 63 CE. The next major conflict was the emperor Trajan’s Parthian War from 115-117 CE. Having already asserted his credentials as a general par excellence with the conquest of Dacia, the emperor turned his attention against Rome’s great imperial rival. Initial Roman successes were brought to an abrupt halt by Trajan’s death. His successor, Hadrian, gave up territory seized by Trajan, and returned the empire to its original frontiers.

Hadrian’s successor was Antoninus Pius. Typically, his reign is not one that many associate with conflict (despite some hints that not all was rosy). What’s more, the emperor never even left Rome! In the later biography of the emperor recorded in the Historia Augusta, while describing the final days of the emperor’s life, the biographer describes that Antonius inveighed against certain foreign kings who had wronged him. One of these was likely Vologases IV, the Parthian King. Late in 161 CE, after Antoninus Pius had passed, Vologases made his move and marched into Armenia.

He expelled the Roman client king and installed his own, called Pacorus. The attempt at retaliation led by the Roman governor, Marucs Sedatius Severianus, was a disaster. His army was trapped in the town of Elegeia on the Cappadocian frontier. Realizing that his desperate situation, Severianus killed himself, leaving his army to be massacred. Worse still, there were pressures elsewhere in the empire. There was unrest in Britain and on the Germanic frontier tribes were massing and crossing into Roman territory. It was shaping up to be a baptism of fire for Antoninius’ successors.

When he died in 161 CE, Antoninus Pius had no sons. Instead, the empire passed into the authority of two adopted successors: Marcus Aurelius and Lucius Verus. A quirk of biology ensured that from Nerva until Marcus Aurelius himself, no reigning emperor had a male heir who could succeed their father to rule. Instead, successors were adopted. The shared rule of Marcus and Verus was a novelty in the empire’s history (although power sharing would emerge as a political policy in later centuries). Ostensibly, power was shared between the two men. However, in practice, Marcus was the more senior partner. He had been consul in 140, 145, and 161 which ensured he was vastly more politically experienced than his adopted brother.

In the east, Parthia was ruled by Vologases IV, the son of Mithridates V. He was a member of the Arsacid dynasty. Despite being the son of the Parthian King-of-Kings, Vologases’ early years were marked by contests between rivals for power. This presents a striking contrast to the comparative stability found in Rome, despite the absence at this time of an explicitly dynastic/hereditary system of succession. After succeeding to the throne, Vologases set about asserting his supremacy. First, he subjected the Characenes to his authority. This was an ostensibly autonomous kingdom located in Iraq (near the Persian Gulf), which nevertheless frequently found itself under the control of the Parthians. Much as he would attempt with Armenia later, Vologases marched into Characene, deposed the King Meredates and appointed his own ruler. His choice, Orabazes II, was likely a relative. This would have allowed the Parthians to exert greater control over the kingdom.

Although he was the senior partner, it was decided that Lucius Verus would be dispatched to lead the Parthian campaign in person. Although Marcus would, in time, be compelled to lead the Roman forces on the Germanic frontiers (and successfully), it was clear to many observers that Verus was healthier and stronger and therefore more suited to the rigors of campaigning. This, at least, is what Cassius Dio suggests. According to the Historia Augusta — which is often littered with inaccuracies and inventions — Verus was dispatched to the east in an effort to bring him to heel by exposing him to the vigors of rule.

The war, it was hoped, would either allow Verus to conduct his debaucheries away from the prying eyes of Rome’s populace or inculcate him with the virtues needed to be emperor. Accompanied by a party of well-respected and experienced governors and soldiers, Verus departed for the east in the summer of 162 CE. His journey took him to Greece, and the cities of Corinth and Athens. In the latter, Verus stayed with Herodes Atticus, the fabulously wealthy Roman senator and leading citizen of the mid-second century CE, and he also was initiated into the Eleusinian Mysteries.

From Greece, the journey east continued via Asia Minor. If the campaign was meant to lead Verus away from the finer things in life, it doesn’t appear to have met with much early success. After stopping at Ephesus, the retinue continued to (and lingered at) the famed luxury resorts on the Aegean coast of Asia Minor.

They arrived in Antioch, perhaps in early 163 CE. This city, one of the most important in Roman Asia Minor, was to be the base from which Lucius Verus conducted the Parthian campaign (as well as taking up a reputedly beautiful mistress, Panthea). To Verus’ credit, the scale of the task facing him was considerable and he set to work. The Syrian army needed extensive training to bring it up to readiness. From Antioch, Verus also traveled north to Ephesus once again, in late 163/164 CE. There, he married Lucilla, Marcus Aurelius’ daughter. The marriage consolidated the connection between the two emperors.

The Roman retaliation against the Parthian Empire began in 163 CE. They enjoyed some considerable successes to begin with. The Roman legions, led by Marcus Statius Priscus, advanced deep into Armenian territory, driving out the Parthian forces. The Armenian capital, Artaxata, was recaptured in 163 CE following a bloody battle. Despite not leading the forces, Lucius Verus was awarded the honorific title Armeniacus (meaning ‘conqueror of Armenia’). The title featured on Verus’ coinage. The reconquest of the Armenian kingdom allowed the Romans to remodel the territory along lines that they found favorable. The Parthian client king was expelled and replaced by C. Iulius Sohaemus. A senator of Arsacid heritage, he became the ruler of the kingdom, which was also given a new capital, Kaine Polis (‘New City’).

This was not the end of the war, however. While Priscus was in Armenia, the Parthian Empire launched a counter-offensive. This was directed against Osroene, another Roman client kingdom in Mesopotamia. Much as they had done in Armenia, the Parthians deposed the Roman’s chosen king and replaced him with their own choice. The Romans had no choice but to march again…

6. The Limits of War: Sackings and Sickness

The Romans dispatched two armies against the Parthians in Mesopotamia. By 165 CE, the first — perhaps led by Martius Verus — had re-occupied the Osroene capital of Edessa and overseen the re-installation of the former king. A second Roman force led by Avidius Cassius — who would blunder badly later and rebel against Marcus Aurelius — advanced down the Euphrates river. At Dura-Europos, Cassius and the legio III Gallica engaged the Parthians in a bloody battle. The Romans continued to push into Parthian territory, and by the end of 165 CE, Cassius’ forces had reached two of the grandest cities in Mesopotamia: Seleucia (on the right bank of the Tigris River) and Ctesiphon (on the left bank). The city of Ctesiphon was sacked, the royal palace torched; keen to avoid a similar fate, the citizens of Seleucia opened their gates to the Romans. It did little good, and the city was sacked.

If the Romans were celebrating their successes, this should have been short-lived. Having advanced so far into Mesopotamia, Cassius’ army was beginning to feel the depredations of war. Amid the privations of a lack of supplies, the Roman forces were soon struck by a devastating pestilence. This was the first sign of the so-called Antonine Plague (also sometimes called the Plague of Galen, after the ancient physician who documented its effects). Scholarly consensus holds that the disease in question was smallpox. Originating with Verus’ forces in the east, the pestilence traveled back with these soldiers and wrought devastation upon the empire.

In all, perhaps as many as 10 million inhabitants of the Roman Empire perished as a result of the plague, which lingered in the empire for decades. Commenting upon a later outbreak of the pestilence in around 189 CE (during the reign of Marcus’ son, Commodus), the historian Cassius Dio — an eyewitness to events — described how as many as two thousand people could die from the disease in Rome in a single day!

Ultimately, the Romans were victorious in the Parthian War of 161-167 CE. After the sacking of Ctesiphon and Seleucia, Lucius Verus took the title Parthicus Maximus. As a feature of his imperial titulature, the epithet conveyed his military might and power. But the question remains: to what extent can the Roman victory over the Parthian Empire be attributed to Verus?

Indeed, much of the successes the Romans enjoyed in this eastern war surely belong to the supremely able retinue of generals and administrators who were with Verus at the time. Regardless, upon his return from the campaign, Verus was awarded a triumph, the traditional celebration of Roman military conquest that had been used since the Republican era. This was to be the high point of Verus’ imperial story, however. In 169 CE, as he was journeying back from the Danubian frontier — where he had been fighting in the Marcomannic wars with Marcus Aurelius — Verus suddenly fell ill and died. It is highly probable, according to historians, that Verus was a victim of the pestilence that his soldiers had carried back to the empire with them from the Parthian War.

Brought back to Rome and mourned by his colleague in power, Verus was deified as Divus Verus. As for Parthia, the empire was chastened, but it endured. The Roman territorial acquisitions — much as they always had been in the east — proved not much more than ephemeral, although some cities (like Dura-Europos) remained in the Roman sphere of influence.

The plague that the Roman army had contracted in the east also likely ensured that the empire would not intervene in the east for several decades after Verus’ campaign. It wasn’t until the very last years of the second century, during the reign of Septimius Severus, that the Parthians again faced Roman aggression. Although he, like Verus, took the title Parthicus Maximus, his conquests proved similarly fleeting, as did the botched campaign of Severus’ son, Caracalla. In fact, Caracalla’s delusions of Parthian conquest resulted in the bellicose emperor’s death, murdered by disaffected staff on a dusty roadside near Carrhae.

The constant warfare had damaged the Parthian state, however. Riven by internal political strife, the Parthian royal line was overthrown. In their place would rise the Sassanian Empire. Equally as formidable, the early Sassanians were fuelled by stung pride and a sense of historical destiny. They viewed themselves as the successors to the great Persian Empires of the past. In the centuries to come, they would be responsible for some of Rome’s most damaging defeats.