Parthian Empire

The Parthian Empire was Rome’s greatest rival in the East. For almost three centuries, the two powers competed for influence over the Near East, frequently clashing over buffer states such as Armenia. Neither side achieved lasting dominance. The Parthians inflicted one of Rome’s greatest military disasters at the Battle of Carrhae in 53 BCE, while the Romans later captured and sacked the Parthian capital of Ctesiphon on several occasions, most notably under Septimius Severus in 197 CE.

The Rise of the Parthian Empire

The Parthian Empire was founded by Arsaces I in 247 BCE and lasted until it was overthrown by the Sasanian Empire in 224 CE. Arsaces rebelled against Andragoras, the former Seleucid satrap of Parthia, who had declared his independence during the weakening of the Seleucid Empire.

For several decades, the new kingdom expanded slowly. Its greatest early gains came under Mithridates I (r. 165–132 BCE), who conquered Media and Mesopotamia from the Seleucids and transformed Parthia into a major imperial power. At its greatest extent, the empire stretched from the Euphrates River in the west to regions bordering modern Afghanistan and Pakistan in the east.

Early Contact with Rome

One of the earliest recorded diplomatic contacts between Rome and Parthia occurred in the late second century BCE, when the Roman commander Sulla met the Parthian king Mithridates II. Although the negotiations achieved little, they marked the beginning of relations between the two expanding powers.

Contact resumed in the mid-first century BCE during Rome’s campaigns against Tigranes II of Armenia. Roman commanders Lucius Licinius Lucullus and Pompey fought a long campaign against Tigranes, while the Parthian king Phraates III became involved after being encouraged by Tigranes’ rebellious son, Tigranes the Younger. Although Rome and Parthia briefly found themselves on the same side, mutual distrust prevented any lasting cooperation.

Armenia soon became the main source of conflict between the two empires. Both Rome and Parthia sought to place friendly rulers on the Armenian throne, creating a long-running struggle for influence that repeatedly brought the two powers into conflict.

The Battle of Carrhae

The first major war between Rome and Parthia began in 53 BC, when Marcus Licinius Crassus invaded Mesopotamia in search of military glory.

Crassus led approximately 42,000 men, including seven legions, through the Syrian desert instead of advancing through Armenia, despite the Armenian king offering support and a safer route. He also dismissed peace envoys sent by the Parthian king Orodes II, determined to win a decisive Roman victory.

Orodes entrusted the defense of the kingdom to his brilliant general Surena, who confronted the Roman army near Carrhae.

Ignoring the advice of his officers, Crassus formed his army into a hollow square, sacrificing mobility for defence. The Parthian horse archers stayed beyond the range of Roman javelins, showering the legions with arrows. Forced into the defensive testudo formation, the Romans became vulnerable to repeated charges by heavily armoured cataphracts. Whenever Roman troops attempted to counterattack, the cataphracts withdrew, allowing the horse archers to cut down the advancing soldiers.

Crassus hoped the Parthians would eventually exhaust their supply of arrows, but Surena had anticipated this by using camel caravans to continually resupply his archers. Roman morale steadily collapsed.

In a desperate attempt to break the deadlock, Crassus sent his son Publius with the Gallic cavalry and supporting troops to drive off the horse archers. Instead, they were lured away from the main army, surrounded, and destroyed. Publius was killed.

After learning of his son’s death, Crassus withdrew to Carrhae under the cover of darkness. The following day Surena offered negotiations, but during the meeting violence broke out and Crassus, along with several senior officers, was killed.

According to Plutarch, around 20,000 Romans died and another 10,000 were taken prisoner. Carrhae remains one of the greatest defeats in Roman military history.

Renewed Conflict

The Parthians remained largely neutral during the civil war between Pompey and Julius Caesar. Although Caesar planned an invasion of Parthia following his victory, his assassination in 44 BCE ended those ambitions.

The Parthians supported the Liberators during the subsequent civil wars. After their defeat, they allied with Quintus Labienus and overran much of Rome’s eastern provinces before Mark Antony drove them back. Antony later launched his own invasion of Parthian territory in 36 BCE, but the campaign ended in failure.

Augustus and the Return of the Standards

Rather than launching another invasion, Augustus pursued diplomacy.

In 20 BCE he negotiated the return of the legionary standards captured at Carrhae, along with surviving Roman prisoners. Although no territory changed hands, the recovery of the standards was celebrated throughout the Roman world as a major diplomatic triumph.

The event is depicted on the cuirass of the famous statue known as the Augustus of Prima Porta, while the recovered standards were housed in the Temple of Mars Ultor in the Forum of Augustus.

Trajan’s Eastern Campaign

Conflict resumed during Nero’s reign over control of Armenia between 58 and 63 CE, ending in a compromise that left Armenia under a Parthian prince accepted by Rome.

The next major war came under Emperor Trajan. Between 114 and 117 CE he annexed Armenia and Mesopotamia before advancing deep into Parthian territory. He captured the capital, Ctesiphon, and even reached the Persian Gulf.

Trajan unsuccessfully besieged the fortress city of Hatra, while widespread rebellions broke out behind his lines in Mesopotamia. Before he could fully restore Roman control and continue the campaign, he died in AD 117.

His successor, Hadrian, abandoned Trajan’s eastern conquests and restored the Euphrates as the frontier between the two empires.

Lucius Verus and Septimius Severus

War erupted again during the reign of Marcus Aurelius in the early 160’s CE. Although Lucius Verus travelled east to oversee the campaign, much of the fighting was conducted by his generals, who successfully invaded Mesopotamia and captured both Seleucia and Ctesiphon. Despite taking little direct part in the fighting, Verus celebrated the victory by adopting the titles Armeniacus, Parthicus, and Medicus.

The final major Roman victories over the Parthians came under Septimius Severus between 195 and 197 CE. Severus captured Seleucia, occupied Babylon, and sacked Ctesiphon. These successes are commemorated on the Arch of Septimius Severus in the Roman Forum.

His son Caracalla renewed the war in 216 CE, sacking Arbela before being assassinated the following year. His successor, Macrinus, suffered defeat at the Battle of Nisibis and was forced to pay a large indemnity to the Parthians.

The End of the Parthian Empire

The Parthian Empire survived for only a few more years. In AD 224, Ardashir I defeated the last Parthian king, Artabanus IV, and founded the Sasanian Empire. Within the following years he captured Ctesiphon, bringing nearly five centuries of Parthian rule to an end.

The rivalry between Rome and Parthia was immediately inherited by Rome and the new Sasanian Empire, beginning a new chapter in the long struggle between the Mediterranean and Persian worlds.

Bibliography:

Goldsworthy, Adrian. Rome and Persia: The Seven Hundred Year Rivalry. Basic Books, 2023.

Isaac, Benjamin. The Limits of Empire: The Roman Army in the East. Rev. ed. Oxford: Oxford University Press, 1992.

Millar, Fergus. The Roman Near East, 31 BC–AD 337. Cambridge, MA: Harvard University Press, 1993.

Ellerbrock, Uwe. The Parthians: The Forgotten Empire. London: Routledge, 2021.