Parthians at Philippi
The Parthian empire had once been an ally of Rome. Parthians and Romans had fought together to finish off the Seleucid Empire in 63 BC, and enjoyed peaceful relations after. This all changed in 54 BC, when the ambitious Roman Marcus Licinius Crassus launched an unprovoked invasion of Parthian Syria with the intent to march on Seleucia and conquer the Parthian empire. Instead, his army was annihilated in the Syrian desert at the Battle of Carrhae. Of Crassus’ 38,000 men, only 8,000 or so made it back to Roman territory. 20,000 Romans were killed, and 10,000 were prisoners in Parthia.
The immediate result of the campaign was a Parthian invasion of Roman Syria under the command of a general named Osaces and Pacorus, the son of the Parthian ruler Shah Orodes II. The death of Crassus and many of his officers left Gaius Cassius Longinus as the ranking Roman commander in Syria. While the Parthians besieged Antioch, Pacorus was recalled to Parthia by his father. Cassius rallied the remaining Roman troops in the area and broke the siege, then defeated the Parthians again at Antigonea. In this battle, Osaces was killed and his troops dispersed.
The first round of Roman-Parthian conflict thus ended in a status quo ante bellum. As a result, like the United States and USSR 2000 years later, the two superpowers of the ancient Near East in the 1st century BC saw continued direct war as too risky and destructive when compared to its potential benefits. Therefore, the struggle between them for regional supremacy turned from confrontation to war by proxy. Struggle between armies was replaced by each side meddling in each other’s internal struggles, supporting rebel factions and fighting proxy battles with client states.
The first shot of the proxy war came from Cassius’ replacement as governor of Syria. Marcus Calpurnius Bibulus arrived in 51 BC to take control of the province from Cassius. He sought to divide the Parthians against each other so as to preclude further invasions of Roman territory. Bibulus befriended a Parthian satrap named Ornodapates, who carried an old grudge against Orodes. Using Ornodapates as a go-between, Bibulus constructed a plot to stage a coup d’etat, overthrow Orodes and install his son Pacorus on the throne in his stead. The plot failed, but the resulting strife temporarily distracted Parthia from any westward expansion.
While the Parthians were otherwise preoccupied, the political situation in Rome was spiraling out of control. Once allies, Julius Caesar and Ganeus Pompey were now enemies. In 49 BC, their rivalry and refusal to disband their armies spilled over into open civil war. Julius Caesar rapidly marched on Rome, forcing Pompey to withdraw to Greece without a fight. Pompey spent the winter of 49-48 BC regrouping in Greece and preparing for a decisive showdown against Caesar.
The Parthians had been allies with Pompey during Pompey’s campaigns against Pontus and the Seleucid Empire, and Orodes was also saw Caesar as an ally of Crassus and was worried that he would continue the pattern of destructive foreign conquest which he had carried out in Gaul. What’s more, Crassus’ surviving son was an officer in Caesar’s forces. As a result, Orodes sided with Pompey, although the extent of the support he provided is not clear.
Caesar defeated Pompey at Pharsalus in 48 BC. Pompey fled to Egypt, where he was assassinated. Caesar continued to campaign against Pompey’s supporters in Egypt, Spain and North Africa until he emerged victorious in 45 BC. After consolidating his political position in Rome, Caesar began planning even more breathtaking conquests. At this point, Plutarch wrote, Caesar’s success only gave him an appetite for further conquest, fueling an “emulation of himself, as if he had been another man, and a sort of rivalry between what he had done and what he purposed to do.” Caesar planned to invade Parthia and conquer and subdue their entire empire. But his plans did not stop there, he also planned to circumnavigate the shores of the Caspian Sea with his army, subdue the Scythians, and then conquer Germany. This would make Rome master of most of the known world.
Some supporters of Caesar in Rome began to spread a rumor that the Sibylline Books prophesied that Parthia would only be conquered by a king, so Caesar should declare himself king to ensure that his expedition was successful. Fear of Caesar’s increasingly monarchist and dictatorial tendencies were confirmed in February of 44 BC when he had the Senate declare him Dictator for Life. By this time, plots were already being made against him. There is no evidence that the Parthians had a hand in the plot to kill Caesar. However, Caesar intended to leave Rome on March 18 to organize the east for the coming invasion of Parthia, and this forced the conspirators to act quickly.
Caesar’s assassination ended his threat to Parthia and touched off a new round of Roman civil wars. Marcus Junius Brutus and Gaius Cassius Longinus fled to the east in the wake of the killing. In the wake of their flight, the Senate was supposed to give them governorships in Syria and Macedonia, but they were instead given the much less wealthy provinces of Cyrene and Crete. Syria and Macedonia were instead given to Caesarian supporters Dolabella and Mark Antony. Octavian, the posthumously adopted son of Caesar, then convinced the Senate to outlaw Antony and attacked his forces at the city of Mutina. As a result, the Senate stripped Antony and Dolabella of their governorships and returned them to Brutus and Cassius.
Cassius entered Syria and took control of the legions stationed there. In the meantime, a renegade Roman general named Caecilius Bassus staged an attempt to carve out a minor kingdom of his own. With one legion, Bassus revolted against Caesar’s commanders who had been preparing for the invasion of Parthia and with Parthian support held a city while besieged by 6 legions. Cassius arrived as the siege was in progress and mediated a solution whereby he took command of all 7 legions. Orodes had sent a small contingent of Parthian soldiers to aid Bassus, and these men joined Cassius’ command.
Cassius gained more troops when 4 legions that had been stationed in nominally independent Egypt marched north and surrendered. He also began to recruit Parthian horse archers into his army. Cassius had faced the Parthians at Carrhae ten years earlier, and he knew how effective their archers could be against infantry in open terrain. On the other hand, Cassius’s skill at withdrawing his command from the disaster at Carrhae, and his subsequent defeat of the Parthians at Antioch earned him the respect of the Parthians that he commanded. It is not clear if these Parthians were recruited as mercenaries or were sent by Orodes II to support Cassius.
Cassius then turned his attention to defeating Dolabella, who still considered himself governor of Syria and had holed himself up in Laodicea. After defeating Dolabella and taking control of his legions, Cassius sent his Parthian horse archers back to the court of Orodes with gifts. The Parthians were accompanied by Quintius Labienus, whose job was to seek Orodes’ support for Brutus and Cassius’ army and ask for significant troop support from the Parthian monarch. Orodes entertained Labienus in his court and dispatched a small force, but no large Parthian army was forthcoming.
In the meantime, Antony and Octavian had reconciled and formed an alliance. They began murdering their political enemies in Rome and confiscating their property in order to fund their armies. At the same time, Brutus began to put together his own army in Asia Minor and Macedonia. After securing their rear by subduing Lycia and Rhodes, Brutus and Cassius crossed over into Thrace and marched to Greece, primed for a showdown with Antony and Octavian.
Brutus’ command had 8 legions, plus 4,000 Gallic and Lusitanian cavalrymen, and 2,000 cavalrymen from Thrace, Illyria, Thessaly and Parthia. Cassius had 11 legions, 2,000 Spanish and Gallic cavalrymen, and 4,000 horse archers from Parthia and its subject regions (Media and the Arab kingdoms). All but two of their legions were understrength, giving a combined total of 80,000 foot soldiers and 12,000 cavalry. This total does not include the foot soldiers and 5,000 cavalrymen supplied by Roman client states in Galatia.
Brutus and Cassius marched their force into northern Greece and encamped them at the Plains of Philippi. Antony and Octavian opposed them with 19 legions. In addition, Octavian had 20,000 cavalry, while Antony had 13,000. Antony and Octavian’s legions were at full strength, giving them 89,680 combat infantrymen and an almost 2-1 edge in cavalry. They also held the advantage that most of their troops were from Italy and all spoke the same language, while Brutus and Cassius had auxilaries and cavalrymen from a dozen nationalities who spoke widely varying languages.
The Battle of Philippi was really two battles, separated by a 20-day standoff. Brutus and Cassius held the high ground, had better supply lines and their navy stood ready to interdict Antony and Octavian’s supply lines from Italy. Antony and Octavian were already low on supplies and had over 30,000 more mouths to feed than Brutus and Cassius. Brutus and Cassius were therefore content to hold the high ground and let Antony and Octavian’s men starve in the plains below.
At this stage in the battle, cavalry from both sides skirmished in front of the armies. Brutus and Cassius’ Parthians likely performed well in these skirmishes and scouting expeditions. Brutus and Cassius’ cavalrymen generally came out on top in these engagements despite their numerical inferiority. This allowed each side to get a feel for their strength. In the meantime, Antony wanted to force a general engagement before his army starved. His men began building a causeway through a swamp on Cassius’ left flank in an attempt to turn his position. Cassius responded by building his own causeway to cut off Antony’s. This trench warfare continued for a few days until Antony lost patience and ordered a frontal attack on Cassius’ positions.
Thus, on October 3, 42 BC the first stage of the battle began (click for map). Antony’s men stormed Cassius’ fortifications, forced the gates and overran Cassius’ camp. On the opposite side of the battlefield, Brutus charged and overran Octavian’s lines, capturing his camp and scattering his forces. But, Cassius did not know this, and thinking the day was entirely lost he had his slave kill him to avoid being captured.
Both sides then fell back to their previous positions. The result of the first day of battle was a draw, with Octavian and Antony losing 16,000 men and Brutus and Cassius losing 8,000. Octavian and Antony attempted to bring reinforcements in by sea, but their convoy was attacked at sea and annihilated with few survivors. As a result, Antony and Octavian’s supply position worsened. Brutus on the other hand had to deal with discontent within his own ranks. Some of his men wanted to settle the matter with a decisive battle, others began to desert. With concerns about the loyalty of Caesar’s former soldiers in his army, Brutus succumbed to the pressure of his officers and launched a second attack on October 23 (click for map). This time, his forces were routed and scattered. Brutus committed suicide to avoid capture.
The defeat of Brutus and Cassius left Quintius Labienus adrift in the Parthian court. Antony, Octavian and Marcus Lepidus divided the empire between them. Orodes took this as an opportunity to seize territory from a weak and divided Rome. Labienus offered to lead a Parthian army, and in 40 BC he crossed the Euphrates and invaded Roman Syria. He was accompanied by Pacorus, who had reconciled with his father after his attempted coup 10 years earlier. They conquered territory as far as Ionia while Antony was distracted by fighting in Italy with Octavian. The Roman commander in the region, Decidius Saxa, was killed battle and the Parthians captured the cities of Apamea and Antioch.
Pacorus then split off from Labienus and marched to Judea. Hyrcanus II, son of Salome Alexandra was the current ruler and a client of Antony. His nephew Antigonus promised Pacorus 1000 talents of gold and 500 Jewish women if he would overthrow Hyrcanus and install Antigonus as the ruler and High Priest. Pacorus invaded Judea from the north, capturing Jerusalem with the help of Antigonus’ supporters. Antigonus was placed on the throne, and he had Hyrcanus’ face mutilated so he would not be eligible to hold the office of high priest. Antigonus never actually paid his price to Pacorus, but remained a Parthian client.
Antony was not content to let Parthia steal his client kingdoms and conquer his territory. He sent Publius Ventidius Bassus to take command of the shattered Roman forces in Asia Minor in 39 BC. Ventidius defeated a Parthian army at the Battle of the Cilician Gates, captured Labienus and executed him. He then drove the Parthians back across the Euphrates. In 38 BC, Pacorus led an attempted counterattack, but was killed in action at Cyrrhestica and his army defeated. Antony and Ventidius then turned to reducing Parthia’s client states. The Arab kingdom of Commagene was attacked, besieged, and placed under tribute. Antony also gave money to Herod to support his attempt to wrest the throne of Judea from Antigonus. With Antony’s backing, Herod raised an army, overthrew Antigonus in 37 BC and installed himself as king. This ended the Hasmonean dynasty, and put Judea back in the pro-Roman camp.
The death of his eldest son Pacorus seems to have greatly affected Orodes, for in 37 BC he abdicated the throne in favor of his son Phraates IV. The Parthian kings all had many wives, and many sons, thereby virtually guaranteeing dynastic struggles. Phraates decided to shortcut this process by executing all of his brothers. His father objected and was executed as well. Many nobles fled the Parthian court in fear.
With Parthia on its heels and torn by internal strife, Antony decided this would be an excellent time to invade the county, conquer their territory and avenge Crassus’ defeat. A Parthian defector named Monaeses fled to Antony and advised him on the invasion. Phraates officially forgave Monaeses and invited him back to Parthia, and Antony allowed him to return, telling him that the Romans only wanted the return of the legion standards and prisoners taken from Crassus in 53 BC. This was simply a ruse designed to make the Parthians complacent. In the summer 36 BC, Antony invaded Parthia with an army of 16 legions and 30,000 auxiliaries. He made a treaty with Artavasdes of Armenia against the Parthians as well, gaining 6,000 Armenian cavalry and 7,000 infantry.
He was delayed in leaving Syria, and his plan to march through Armenia and attack Parthia from the north ran out of time to be effectively executed. His forces were drawn out and attacked, with the more mobile Parthian forces confounding Antony. Artavasdes took his forces and abandoned the failing enterprise. Forced to retreat, Antony’s men were forced to endure 19 days of constant Parthian attacks before making it back to friendly territory. Antony’s Parthian disaster cost him 24,000 men killed, about half in combat and half by disease. These men were sorely needed for the coming struggle with Octavian for supremacy in the Mediterranean world. Antony tried to recover by invading Armenia and punishing Artavasdes for his treachery in 33 BC, and encouraging the Medes to revolt against Parthian rule.
Further Parthian strife occurred in 33 BC, when the Parthian noble Tiridates revolted against Phraates. He seized the Parthian capital and forced Phraates to flee. Phrates returned and overthrew Tiridates in 30 BC. Tiridates fled to Rome and was given shelter there. By this time, Antony had been defeated by Octavian and committed suicide. Octavian, now known as Augustus, sought to secure Rome’s borders and consolidate Roman control throughout the empire rather than continue expansion. Phraates sought the return of Tiridates from Rome to face punishment, but Octavian refused. The two sides came to a peace agreement to end 34 years of on-again, off-again warfare in 20 BC. The Parthians agreed to release the remaining prisoners taken from Antony and Crassus’ armies, and return the legion standards captured from their armies. The return of these standards was highly celebrated in Rome.
The result was a period of peace between Rome and Parthia as each of them recognized that they both stood to benefit from stability in the region. Throughout their 34 year struggle, each side sought to gain an advantage over the other without committing enough force to risk losing a decisive battle (Caesar’s planned invasion and Antony’s invasion were the exceptions). Instead, they fought primarily through intrigue, supporting each other’s internal factions, and fighting through client states. This was occasionally punctuated by events such as Labienus’ invasion of Asia Minor and Antony’s Parthian Campaign. Such limited war carried far less risk than a general confrontation of the type Julius Caesar planned, but the potential payoff was also far less. As a result, both sides were stalemated. In 54 BC, the boundary between Rome and Parthia was the Euphrates River. In 20 BC, the boundary was still the Euphrates River. No significant territory changed hands due to the conflict. What they did do was successfully defeat each other’s expansionist ambitions. Thus, the Parthian-Roman conflict ended a strategic stalemate, which is why both sides were able to end the conflict through negotiation without giving up any territory.
 Justin, Epitome of the Philippic History of Pompeius Trogus, Corpus Scriptorum Latinorum, trans. by John Selby Watson. 1853, http://www.forumromanum.org/literature/justin/english/index.html (accessed July 15, 2011), 40.5; Cassius Dio, Roman History, LacusCurtius, trans. by Earnest Cary. 1914, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Cassius_Dio/home.html (accessed July 15, 2011), 40.25, 28-30.
 Justin, Epitome of the Philippic History of Pompeius Trogus, 40.4; Cassius Dio, Roman History, 40.30.
 Justin, Epitome of the Philippic History of Pompeius Trogus, 40.4.
 Plutarch, Life of Caesar, LacusCurtius, trans. by Bernadotte Perin, 1919, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Lives/Caesar*.html (accessed November 16, 2011), 58.4-7.
 Plutarch, Life of Caesar, 60.1-2; Ramon L. Jiménez, Caesar Against Rome: The Great Roman Civil War (New York: Praeger, 2000), 234-235.
 Appian, Civil Wars, LacusCurtius, trans. by Horace White, 1913, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Appian/Civil_Wars/4*.html (accessed November 16, 2011), 4.57-58.
 Appian, Civil Wars, 4.58; Sir Percy Molesworth Sykes, A History of Persia, Vol. 1 (London: McMillan & Co., 1915), 384.
 Appian, Civil Wars, 4.59.
 Appian, Civil Wars, 4.63; Sykes, A History of Persia, Vol. 1, 384.
 Appian, Civil Wars, 4.88.
 Appian, Civil Wars, 4.108, 137.
 Appian, Civil Wars, 4.108-109; Plutarch, Life of Brutus, LacusCurtius, trans. by Bernadotte Perin, 1919, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Lives/Brutus*.html (accessed November 17, 2011), 39.8.
19 full-strength legions would contain 89,680 combat troops and 101,080 total men.
 Appian, Civil Wars, 4.108-137; Plutarch, Life of Brutus, 39-52.
 Plutarch, Life of Antony, LacusCurtius, trans. by Bernadotte Perin, 1919, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Lives/Antony*.html (accessed November 17, 2011), 29, 32; Sykes, A History of Persia, Vol. 1, 384-385.
 Josephus, Antiquities of the Jews, trans. by William Whiston, 1737 from http://sacred-texts.com/jud/josephus/index.htm#aoj (accessed November 17, 2011), 14.13.3-10.
 Sykes, A History of Persia, Vol. 1, 385-386; Plutarch, Life of Antony, 33.1-34.6; Josephus, Antiquities of the Jews, 14.14.1-14.16.4.
 Sykes, A History of Persia, Vol. 1, 386-387; Plutarch, Life of Antony, 37.1.
 Plutarch, Life of Antony, 37.1-51.1; Sykes, A History of Persia, Vol. 1, 387-390.
 Sykes, A History of Persia, Vol. 1, 387-390; Justin, Epitome of the Philippic History of Pompeius Trogus, 40.5.
Image Sources: (Header) http://commons.wikimedia.org/wiki/File:Philippi_plain_acropolis.jpg; http://www.saudiaramcoworld.com/issue/198804/main.street.of.eurasia.htm; (Body) http://commons.wikimedia.org/wiki/File:CaesarTusculum.jpg; http://en.wikipedia.org/wiki/File:Coin_of_Orodes_II_of_Parthia.jpg; http://en.wikipedia.org/wiki/File:CaesarTusculum.jpg; Map based on free educational map from the Maps for Students Page at the Ancient World Mapping Center; Map modified from http://en.wikipedia.org/wiki/File:1stMithritadicwar89BC.png; http://en.wikipedia.org/wiki/File:MarkAntony1.jpg.
Article © Christopher Jones 2011.