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date: 29 September 2023

Parthian-Roman Warsfree

Parthian-Roman Warsfree

  • Jason M. Schlude


Founded and ruled by the Arsacid royal family, the Parthian empire (c. 250 bce–227 ce) was the native Iranian empire that filled the power vacuum in the Middle East in the midst of Seleucid decline. Arsacid interaction with the Roman empire began in the mid-90s bce, eventually established the Euphrates river as a shared border, and was peaceful in nature till 54 bce. In that year, the first of four cycles of Parthian-Roman wars began. Since the Romans carried out the initial large-scale mobilization of troops that introduced most of these wars, it is appropriate to associate these four cycles with the various Romans who coordinated the Roman military efforts: (a) Crassus to Antony (54–30 bce); (b) Nero (57–63 ce); (c) Trajan (114–117 ce); and (d) Lucius Verus to Macrinus (161–217 ce). The fundamental causes for these conflicts were Roman imperialism, which was well ingrained by the 1st century bce, and Parthian imperialism, which accelerated in the 2nd century bce, probably accompanied by the Arsacids’ attempts to present themselves as successors to the Achaemenid dynasty. These traditions led the Romans and Parthians to expand their spheres of power such that they came to meet in Armenia and Mesopotamia, over which regions they fought at different points for the three-century period of their empires’ coexistence. Even so, Rome and Parthia enjoyed lengthy periods of peace. Conflict was neither inevitable nor constant. In many cases (particularly in the late 1st century bce and 1st century ce), Romans and Parthians alike preferred peace and succeeded in maintaining it; but they presented diplomatic negotiations and limited military actions in ways that proclaimed hostility and martial victory (real and imagined). In this way, however, the persistent image of conflict conditioned the Roman people, especially, to accept and even expect such war. This aggressive anti-Parthian rhetoric, for example, enabled Emperor Trajan to break with years of peace and invade Mesopotamia (114–117 ce). In this way, the image of Parthian-Roman war was made a reality.


  • Near East
  • Roman History and Historiography

Peace before War

The Parthian and Roman empires were often in conflict—an understandable development since both Rome and Parthia strove to expand their hegemony in the Levant and Mesopotamia in the 1st century bce. This conflict arose in the mid and late 1st century bce, when the Arsacid dynasty faced Roman governors and generals in Syria who exercised significant independent authority, and it continued in the 1st through early 3rd centuries ce, when emperors dominated Rome.

Yet to assume the relationship between Parthia and Rome was one unbroken chain of relentless conflict is problematic. In fact, this relationship began with an interest in peace. In the mid-90s bce (probably 96/95 bce), Mithridates II of Parthia (r. 123–88/87 bce) sent his envoy Orobazus to the banks of the Euphrates to meet with Sulla and request “alliance and friendship” (συμμαχίαςκαὶφιλίας‎) of the Romans (Plut., Sull. 5.4; cf. Livy, Per. 70). The meeting proved controversial, with Sulla arranging a public audience in which he took center stage as powerbroker of the Near East. As a result, Mithridates later had Orobazus executed (Plut., Sull. 5.5), and one hears of no subsequent endorsement of a Roman-Parthian treaty by the Roman senate. Yet, later authors like Festus indicate the Arsacids obtained the desired friendship (amicitias) (Brev. 15), and Orosius even speaks of a Parthian foedus (“treaty”) struck with Sulla (1.46.4). Such assertions are questionable, but their existence is a clear indication that Roman-Parthian relations following 96/95 bce were peaceful in practice. That general pattern seems not to have changed for over 30 years.

Rome’s three wars with Mithridates VI of Pontus (r. 120–63 bce) in 89–85, 83–81, and 74/73–63 bce brought the Parthians and Romans into contact many times. The extant evidence specifically documents their exchanges during the Third Mithridatic War. The circumstances were tense: the Arsacids were called upon for assistance, by Mithridates VI and his ally Tigranes II of Armenia (r. 95–56 bce) and by the Roman generals Lucullus and Pompey. And they remained tense when Rome defeated Mithridates VI and Tigranes and dismantled the Armenian empire, producing a power vacuum in which Rome and Parthia saw opportunities for expansion.

Yet they avoided war. Around 72/71 bce the Arsacid Sinatruces (r. 76/75–70/69 bce) refused Mithridates VI’s first request for aid (Memnon, FGrH 434 F 29.6(43)). When his successor, Phraates III (r. 70/69–58/57 bce), faced competing embassies shortly after 69 bce, now from Mithridates VI and Tigranes on the one hand and Lucullus on the other, Phraates entertained both sides favorably (resulting in charges of double-dealing), but effectively maintained neutrality (Memnon, FGrH 434 F 38.8(58); Sall., Hist. 4.69.1–23; App., Mith. 13.87; Dio Cass. 36.1–3; Plut., Luc. 30.1). In consequence, Lucullus supposedly tried to set in motion a campaign against Phraates (Plut. Luc. 30.2–31.1), but this is highly unlikely, considering Tigranes had yet to submit to him, and such claims were probably fabricated or exaggerated by rivals at Rome. At any rate, no campaign materialized.

Much to Lucullus’ displeasure, Tigranes never submitted to him. Before this could happen, Lucullus’ rivals orchestrated his recall, and command of the Third Mithridatic War was awarded to Pompey in 66 bce. Pompey compelled Tigranes to surrender and oversaw the dismantling of his Armenian empire. This caused tension between Parthia and Rome—not because the Arsacids supported Tigranes, but because they saw an opportunity to reassert power in northern Mesopotamia even as Rome was establishing its own hegemony. Such tension was evident when Phraates occupied the territory of Gordyene, which Tigranes had controlled, only to have Pompey expel him and return it to Tigranes, and when Phraates displayed anxiety and displeasure at Pompey’s subordinates, Gabinius and Afranius, leading Roman troops east of the Euphrates (Dio Cass. 37.5.2–5; Plut., Pomp. 36.2). Even so Phraates and Pompey avoided real military engagement and cooperated. For example, in 66 bce, Pompey secured the friendship of Phraates and his promise to invade Armenia—a promise, contrary to the suggestion of some moderns, that Phraates fulfilled when he outfitted Tigranes’ son to invade his father’s kingdom (Dio Cass. 36.45.3; 36.51.1–2). Furthermore, Phraates’ protests in response to certain Roman movements in Mesopotamia may be understood as good evidence that Phraates and Pompey had agreed to recognize at least the middle Euphrates as a boundary of the Roman and Parthian spheres (Plut., Pomp. 33.6 should be read in this light). One could point to other developments as well. When Phraates was in conflict with Tigranes over still another disputed territory, Phraates accepted Roman arbitration of the scuffle (Dio Cass. 37.6.3–5; 37.7.1–4; App., Mith. 16.106; Plut., Pom. 39.3). Such progressive developments challenge the long–held assumption that Pompey provincialized lower Cilicia and Syria in 64/63 bce, in direct opposition to the Parthians. At the least, it is unlikely that Pompey did so as an aggressive move against them, and it is worth entertaining the hypothesis that Pompey’s decision squared with Parthian-Roman recognition of the Euphrates as a border and reflected Parthian-Roman cooperation. In short, Pompey oversaw positive developments in Parthian-Roman relations.

Nor was this the end of cooperation. To be sure the Roman general Crassus dramatically introduced a lengthy period of conflict between Rome and Parthia, starting in 54 bce and persisting through Antony’s time in the Near East in the late 40s and 30s bce (see “First Cycle: Crassus to Antony (54–30 bce)”). But from 31/30 bce on, Octavian, later known as the first Roman emperor Augustus (r. 31/30 bce–14 ce), worked with Phraates IV of Parthia (r. 38–2 bce) and then his son Phraates V (r. 2 bce–4 ce) to restore peace. Their accomplishment was not slight. When Octavian’s contest with Antony ended with the latter’s demise in 31/30 bce, the Parthians experienced similar domestic troubles. Phraates was struggling with Tiridates II for the Parthian throne—and both called for Roman assistance (Dio Cass. 51.18.2). Indeed, forced to flee the Parthian empire, Tiridates took hostage a son of Phraates and sought refuge in the Roman empire. But Augustus successfully walked the political tightrope. He protected Tiridates, but returned the boy c. 25 bce (Dio Cass. 51.18.3; 53.33.1–2; Just., Epit. 42.5.9). Then, in 20 bce, when Augustus was in the east overseeing, at the behest of the Armenians, the Roman installation of Tigranes III as king of Armenia, Phraates reciprocated by restoring to Augustus the Roman standards Crassus lost to the Parthians—a gesture also endorsing Roman hegemony over Armenia (Mon. Anc. 29; Strab. 16.1.28; Vell. Pat. 2.91.1; Suet., Aug. 21.3; Dio Cass. 53.33.1–2; 54.7.1–8.1; 54.9.1–10). Their trust and dependence were reinforced c. 10 bce, when Phraates sent several sons to live at the Augustan court in Rome (Strab. 16.1.28; cf. 6.4.2; Mon. Anc. 32.2; Vell. Pat. 2.94.4; Joseph., AJ 18.42; Tac., Ann. 2.1; Suet., Aug. 21.3; Eutr. 7.9; Oros. 6.21.29). War threatened in 2 bce, when Phraates V succeeded, intervened in Armenia, and demanded the return of his brothers. This drew an aggressive response from Augustus, who commissioned his adopted son Gaius to lead troops to the region. Yet, before any clash, compromise and peace won the day. Phraates withdrew his demands, Augustus pledged to keep his brothers in Rome and reasserted Roman authority in Armenia, and Gaius and Phraates renewed the Roman-Parthian treaty on the banks of the Euphrates in spectacular fashion in 2 ce (Dio Cass. 55.10; Joseph., AJ 18.39–43; Vell. Pat. 2.101.1–3).

Rome and Parthia avoided direct conflict until the late 50s and 60s ce under Nero, when the Parthians again intervened in Armenia (see “Second Cycle: Nero (57–63 ce)”). But even then, developments were not totally out of step with Roman-Parthian relations under Augustus. Eventually, they found a solution: henceforth Parthia would appoint the Armenian king (often an Arsacid prince), but Rome would approve his selection. Thereby peace was reestablished in 66 ce (Tac., Ann. 15.28–31; Dio Cass. 62.23.2–3; 63.1–7; Suet., Ner. 13). This peace lasted till the reign of Trajan, who campaigned across Armenia and Mesopotamia against the Parthians between 114 and 117 ce and altered the trajectory of the Roman-Parthian relationship (see “Third Cycle: Trajan (114–117 ce)”). While the Romans and Parthians avoided war for a lengthy time between 117 and 161 ce, and shorter periods of peace existed in the years thereafter, once conflict resumed between Romans and Parthians in 161 ce, it was more extreme and persistent (see “Fourth Cycle: Lucius Verus to Macrinus (161–217 ce)”). Trajan showed the Parthians how the Romans could damage their position in the Near East, and he provided Romans with a model for a more destructive relationship with Parthia. All of this encouraged more active hostility on both sides.

Cycles of Wars

The wars between Rome and Parthia were multiple. Crucially, however, one should avoid reducing them to a series of completely unconnected events. Patterns of conflict existed, and it is appropriate to speak of cycles of Roman-Parthian wars. Since Romans normally initiated the war (whatever the causes, on which see “The Causes and Significance of the Wars”), it makes sense to identify the cycles by the principal Roman aggressors: (a) Crassus to Antony (54–30 bce); (b) Nero (57–63 ce); (c) Trajan (114–117 ce); and (d) Lucius Verus to Macrinus (161–217 ce).

First Cycle: Crassus to Antony (54–30 bce)

Crassus began the clash of arms. Following his second consulship of 55 bce, he departed Rome still in the winter of 55/54 bce to take up the governorship of Syria. As proconsul he entered the Parthian empire with some seven legions, despite no Parthian provocation (Plut. Crass. 14–33; Dio Cass. 39.33.2; 40.12–27). More important to Crassus was increasing his military prestige and already considerable wealth. The conflict was spread over two campaign seasons. The first was limited in scope (Dio Cass. 40.12.2–13.4; Plut. Crass.17.1–4). In 54 bce, Crassus crossed the Euphrates into Osrhoene and concentrated on the region between the Euphrates and Balissus rivers. He besieged and conquered Zenodotia, plundering its property and enslaving its inhabitants, for which his troops hailed him imperator. Afterward, he routed a small force under the Parthian satrap Silaces; but then, rather than follow up the victory, he installed Roman garrisons in the area and returned to Syria for the winter. There he collected provincial revenues, temple monies, and monetary donations given by local peoples and dynasts in lieu of soldiers (Plut. Crass. 17.4–5; Joseph., BJ 1.179; AJ 14.105).

Next followed the second, disastrous campaign. In 53 bce, Crassus declined the invitation of Armenian king Artavasdes II to invade the Parthian empire via Armenia, since he wished to collect the troops he had installed in garrisons east of the Euphrates (Plut., Crass. 19.1–2). Instead, he crossed into Mesopotamia at Zeugma to gather them and proceeded south along the Euphrates. He was then informed by a local (perhaps the Arab tribal leader Ariamnes or Abgarus of Osrhoene) that a modest Parthian force was nearby and under the command not of King Orodes II (r. 57–37/36 bce), but of the noble Surenas and Silaces (Plut., Crass. 19.3–21.4; Dio Cass. 40.20.1–21.4). Crassus jumped at the opportunity for more victories, but none were forthcoming (for the following, see Plut., Crass. 21.5–31.7; Dio Cass. 40.21.2–27.4). Surenas surrounded his infantry with cavalry, which kept distant from and slaughtered them with arrows. The Romans retreated to Carrhae and attempted further flight. Yet only a few escaped, including Crassus’ quaestor Cassius, who made it to Syria. The Parthians also captured multiple Roman standards—a dishonor never forgotten. In the end, Crassus accepted an invitation to parley with Surenas and was killed when violence broke out. It is unclear whether Surenas intended this. One legend has it that Crassus’ head and hand were cut off and sent to Armenia, where Orodes was celebrating a new matrimonial alliance with Artavasdes. The Armenian had shifted allegiance from Rome to Parthia, and at this time they cemented their relationship through intermarriage. There, the head was used as a prop in a staging of Euripides’ Bacchae (Plut., Crass. 32.1; 33.1–4). Another legend suggests that the Parthians filled his mouth with molten gold (Dio Cass. 40.27.3). What is certain is that Crassus instigated a war that made Parthians apprehensive about a Roman presence in the Near East and Romans desirous for revenge.

The result was more violence, first at Parthian, then at Roman initiative. In the two campaign seasons following the battle of Carrhae, the Parthians crossed over into Syria to protest the previous Roman action and to demonstrate that the Roman empire was also vulnerable. The effort in 52 bce involved no more than a small Parthian cavalry force. Cassius, now acting governor of Syria, repelled them easily (Dio Cass. 40.28.1). The subsequent year saw a more substantial Parthian effort. In August 51 bce, Orodes sent his son Pacorus and general Osaces into Cyrrestice, where they camped at Tyba. From there, they attacked Antioch, Rome’s provincial capital, and then threatened its environs. Eventually, Cassius ambushed them and killed Osaces; finally, after the first part of 50 bce, Pacorus returned to the Parthian empire (Dio Cass. 40.28.3–30.3; Cic., Fam. 2.17; 3.3; 3.8; 8.5; 8.7; 8.10; 15.1–4; Att. 5.9; 5.11; 5.14; 5.16; 5.18; 5.20–21; 6.1–2; 6.4; 6.6; 6.8; 7.2; 7.26; 8.11). In subsequent years, Orodes changed tactics again. Now he participated in the Roman civil conflict of the 40s bce. To be sure, he only discussed the prospect of assisting Pompey against Caesar in 48 bce; he provided no material assistance (Dio Cass. 41.55.3–4). But in the winter of 45 bce, he sent troops to relieve the Pompeian Q. Caecilius Bassus, then besieged in Apamea by the Caesarian G. Antistius Vetus (Cic., Att. 14.9; Dio Cass. 47.26.3–28.4; Strab. 16.2.10; Joseph., AJ 14.268–272; App., B Civ. 4.58–59). In 42 bce, he sent archers and cavalry to Caesar’s assassins, Cassius and Brutus, to use against Antony and Octavian, inheritors of Caesar’s cause (App., B Civ. 4.59; 4.63; 4.88; 4.99; Just., Epit. 42.4.7). This aid was not enough; Antony and Octavian won the war and took control of the Roman state as triumvirs, Antony managing the Roman East. Some have interpreted this behavior of Orodes as anti-Roman, but it may be he was looking to build bridges with Roman factions potentially willing to work with Parthia. In the end, however, Orodes turned to a full-scale invasion of Syria in 40 bce. Under his orders, Pacorus and the elusive Roman commander Q. Labienus conquered Syria, Phoenicia, and Judea. It was only in 39 bce that Antony’s subordinate Ventidius eliminated Labienus and repelled Pacorus from the region. Pacorus returned in 38 bce, but Ventidius defeated and killed him in Cyrrestice (Dio Cass. 48.24–27; 48.39–41; 49.19–23; Joseph., BJ 1.248–357; 1.433; AJ 14.330–491; 15.11–14; 15.181; 20.245).

Now it was the Romans’ turn. Despite Ventidius’ victories over the Parthians, Antony decided an additional, aggressive response was necessary in the 30s bce. In 36 bce, Antony led a force, reportedly of at least thirteen legions, into the Parthian empire (Plut., Ant. 37–51; Dio Cass. 49.24.2–31.4; Vell. Pat. 2.82.1 and Livy, Epit. 130 comment on numbers). This time, Antony focused Roman energy on Media Atropatene, and the Romans invaded from Armenia, still ruled by Artavasdes II. Yet the result on the ground was still defeat. It is true that Antony began a siege of the city of P(h)raaspa, the capital city of Media Atropatene, ruled by the Parthian ally Artavasdes I, king of the Medes (not to be confused with his namesake Artavasdes II, king of Armenia). When he found himself approached by the next Arsacid king, Phraates IV, and Artavasdes I, he was able to rout the Parthian forces (Plut., Ant. 39.2–5; Dio Cass. 49.26.2). It is equally true that, even after Antony failed to carry the city and retreated under Parthian pressure, he managed to defeat the Parthians in eighteen engagements (Plut., Ant. 50). But such achievements were counterbalanced by failures. Early on in the campaign, he left behind his baggage train to catch the enemy by surprise. Phraates, however, sent some forces to attack it. As a result, they slaughtered the Roman troops guarding the supplies and siege equipment, destroyed the materials, and stole away with still more Roman standards. All this was made easier since Artavasdes II, who once again appeared willing to help these Romans (perhaps disingenuously), deserted them and fled home (Dio Cass. 49.25.2–26.1; Plut., Ant. 38.2–39.1). In addition, whatever engagements Antony won in flight’s course, the broader context was a failed siege and wretched winter retreat that wasted Roman forces. Reportedly, Antony set out with 100,000 men (Plut., Ant. 37), but lost 32,000 (Plut., Ant. 50–51), whether by war or weather. In subsequent years, he seems to have retained interest in the possibility of another Parthian campaign, but in practice, he focused on controlling Armenia and winning over the king of Media Atropatene (Dio Cass. 49.33.1–4, 49.39.1–40.4, 49.44.1–4; Plut., Ant. 52–53). Civil war with Octavian intervened before Antony could do anything further. Following Antony’s defeat and death, Octavian and Phraates brought the phase of Parthian-Roman war to an end and restored peace (see “Peace before War”).

Second Cycle: Nero (57–63 ce)

Both Parthians and Romans had long wished to control Armenia, but the contest for domination was not so intense that it specifically produced Roman-Parthian warfare before the time of Nero (r. 54–68 ce). For example, Phraates V intervened in Armenia, and Augustus responded by mobilizing troops—but conflict was avoided. And years after Artabanus II (r. 12 to about 38 ce) became Parthian king in 12 ce, he attempted to establish his control over Armenia by installing his son Arsaces as its king in 34 bce (Tac., Ann. 2.1–4; 6.31; Dio Cass. 58.26.1). Yet this time, though the response of Tiberius did indeed result in warfare, it was not directly between Romans and Parthians. While Tiberius mobilized Roman troops on the Euphrates under his general Vitellius, they saw no action. Rather, Tiberius had the Iberians push the Parthians out of Armenia and imposed the Iberian Mithridates on its throne. Tiberius also sent rival Arsacid claimants, then resident in Rome, to the east to challenge Artabanus in the Parthian empire. The first, a son of Phraates IV, died prematurely. The second, Tiridates III, entered Mesopotamia and found Parthian support but ultimately was forced to flee and so returned to the Roman empire (Tac., Ann. 6.31–37; 6.41–44; Dio Cass. 58.26.2–4; 59.27.3; Joseph., AJ 18.96–104). Again, there was no direct Roman-Parthian clash of arms.

This changed, however, under Nero (r. 54–68 ce) and Vologases I (r. 51/52–78/79 ce). Soon after Vologases assumed the Arsacid throne (c. 52–54 ce), he installed his brother Tiridates as king of Armenia (Tac., Ann. 12.50–51). This drew an aggressive response from Nero, who introduced a second cycle of Roman-Parthian war. Nero and his advisors promptly mobilized Roman forces in the east upon receiving news of Vologases’ activities in Armenia, and they tried to use them between 57 and 63 ce to intimidate the Parthians and to regain control of Armenia. This Roman effort was led by the generals Corbulo and Paetus. As for the Parthians, Vologases did not back down. The result was a head-on collision. In 58–59 ce, Corbulo defeated Parthian forces in Armenia (Tac., Ann. 13.34; 13.40). In 61 ce, Vologases publicly declared his intention to fight Rome, crowned Tiridates king of Armenia, and sent Parthian troops to besiege Tigranocerta, the Armenian capital, which then housed Roman troops (Tac., Ann. 15.2; 15.4–5; Dio Cass. 62.20.2–3). In 62–63 ce, while Corbulo forced the Parthians from the east bank of the Euphrates and established a bridgehead there, the Parthians forced Paetus to surrender and humiliated him and his Roman troops at Rhandeia to the north on the border of Armenia and Cappadocia (Tac., Ann. 15.7–17; Dio Cass. 62.21–22). Finally, to make up for Paetus’ defeat, Nero had Corbulo invade Armenia again and confront the forces of Vologases and Tiridates (Tac., Ann. 15.25–27; Dio Cass. 62.22.4–23.1). Only at this point did the Romans and Parthians reach a compromise: Tiridates would remove his diadem and place it at the feet of a statue of Nero, all in front of the legions, and then travel in person to Rome for Nero to crown him before the Roman people. This event took place in 66 ce (Tac., Ann. 15.28–31; Dio Cass. 62.23.2–3; 63.1–7; Suet., Ner. 13).

It is worth noting the significance of this treaty, established at Rhandeia in 63 ce. In essence, it established that the Parthians would choose the king of Armenia, who would then seek formal approval by the Roman emperor. This was different from the agreement of 20 bce, renewed in 2 ce, which established Roman suzerainty over Armenia without any such compromise.

Third Cycle: Trajan (114–117 ce)

This peace held until Trajan (r. 98–117 ce), who introduced a third cycle of war with his Parthian campaign of 114–117 ce. His motives are debated. Perhaps, after his successful Dacian campaign, he contemplated a final, unmatched coup: the successful invasion of the Parthian empire. The idea is plausible. What is certain, however, is that the Parthians provided the more immediate cause. Shortly after Trajan’s Dacian war, the Arsacid Osroes (r. 109/110–128/129 ce) seized the Parthian throne and installed his nephew Axidares (= Exedares) as king of Armenia c. 109/110 ce (Dio Cass. 68.17.1). But by fall 113 ce, Osroes had removed Axidares and effectively installed the latter’s brother, Parthamasiris, as king of Armenia instead (Dio Cass. 68.17.2–3). This broke the protocol established under Nero and Vologases, inasmuch as formal approval of the appointment had not been sought and gained from Rome. Yet the solution was relatively simple: submission of Parthamasiris to Trajan, who then could officially appoint him king.

Events did not play out this way. In fall 113 ce, Osroes sent to Trajan (then in Athens), asked for peace, offered gifts, and requested he send a diadem to Parthamasiris, officially appointing him. But as Dio recounts, Trajan rejected the gifts and refused to approve Parthamasiris. Instead, he replied, “Friendship is judged according to deeds and not words, and therefore he would do all that was appropriate when he reached Syria” (Dio Cass. 68.17.3). Next, Parthamasiris tried to open communications with Trajan. His first attempt was ill conceived; in spring 114 ce, when Trajan (now in Syria) was mobilizing troops and moving from Antioch to Satala, Parthamasiris wrote to him and self-identified as “King.” Trajan offered no reply. Parthamasiris tried again, leaving off the title of King and asking that the Syrian governor M. Junius be sent so that a request might be made through him. Again, Trajan undermined the diplomatic process, sending the governor’s son instead (Dio Cass. 68.19.1–2). Still, hope for a diplomatic solution seemed to remain; through negotiation, they arranged a formal meeting at Elegeia in Armenia the same spring. The meeting, however, was full of the unexpected. First, Parthamasiris insulted the Romans by arriving late, claiming trouble from Axidares (Arr., Parth. 38). Then there was the meeting itself. Parthamasiris acted according to protocol established by Nero and Tiridates. In the presence of the Roman troops and his own entourage, Parthamasiris approached Trajan, saluted him, and laid his diadem at the Roman’s feet, expecting Trajan to return it. But Trajan, breaking with protocol, declared that “he would hand Armenia over to no one, since it belonged to the Romans and would have a Roman governor” (Dio Cass. 68.19.2–68.40.4; Fest., Brev. 20). Parthamasiris was killed (Arr., Parth. 39–40; Eutr. 8.3).

Trajan had a more ambitious agenda. Between 114 and 116 ce, Trajan led an army of about 80,000 men (perhaps eight legions plus supporting troops) on extensive campaigns in the western part of the Parthian empire. While one can be confident about the basic actions, the chronology remains shaky, since the literary evidence is epitomized (e.g., Dio by Xiphilinus) or fragmentary (e.g., Arrian’s Parthica). Still, when the literary record is considered in light of coins and the Fasti Ostienses, the following reconstruction becomes most plausible. In 114 ce, Trajan brought Armenia under control and annexed it as a province (Dio Cass. 68.23; Eutr. 8.3). The senate responded by honoring Trajan with the title of Optimus (Dio Cass. 68.23.1; Plin., Pan. 2). Then in 115 ce, Trajan orchestrated a two-pronged advance into upper Mesopotamia, which he also annexed. He conquered Batnae, Nisibis, Singara, and perhaps also Hatra and Dura Europos at this point (Dio Cass. 68.23.2; 21–22; Arr., Parth. 54–56; Eutr. 8.3; Fest., Brev. 20). The senate next voted him the title Parthicus in February 116 (Dio Cass. 68.23.2; Fasti Ostienses—see Lepper’s discussion).1 Finally, in the same year, he conquered southern Mesopotamia. He began by conquering Adiabene (Dio Cass. 26.1–4; 22.3), which some sources indicate was annexed as Assyria (Eutr. 8.3, but this is late). From there the Romans moved south in at least two divisions, one led by Trajan down the Euphrates, the other down the Tigris. Once Trajan conquered Babylon, he crossed the Tigris and took possession of the western Parthian capital city Ctesiphon, unopposed (Dio Cass. 68.26.4–68.28.3; Arr., Parth. 67). With this, Trajan accomplished what no Roman had before, and the Roman empire reached its greatest extent.

Figure 1. Trajan installing Parthamaspates as Arsacid King at Ctesiphon. Trajan places the diadem upon his head with his right hand, offering the new king to a supplicant representative of the Parthian people. The reverse legend reads: REX PARTHIS DATUS (“A king has been given to the Parthians”).

Yet Trajan’s accomplishment was short-lived. As soon as 116 ce, revolts broke out in Mesopotamia and Armenia against the Romans under leadership of Osroes’ brother Mithridates and then, after Mithridates’ untimely death, his son Sanatrukes. The rebellion included notable cities like Edessa, Nisibis, Hatra, and Seleucia (Dio Cass. 68.29.3; 68.31.4; 75.9). The Jews also revolted at this time in the eastern Mediterranean, especially in Cyrene, Egypt, and Cyprus (Dio Cass. 68.32). It is debated as to whether this was in coordination with the Parthian rebels. Trajan tried to regain control of the situation. L. Quietus recovered Nisibis and burned Edessa (Dio Cass. 68.30.2). Erucius Clarus and Julius Alexander took Seleucia and fired it (Dio Cass. 68.30.2). When Vologases, the son of Sanatrukes, led an army against the Romans (presumably after the death of Sanatrukes), Trajan arranged a peace with him in return for part of Armenia (Dio Cass. 68.75.9). This was clearly a compromise. He tried to head off further conflict by appointing to the Arsacid throne Parthamaspates, the estranged son of king Osroes. The installation was dramatic, with Trajan fixing a diadem upon him publicly in Ctesiphon (Dio Cass. 68.30.3). This allowed Trajan to present the king as vassal to Rome. Indeed, coins celebrating the event sported the inscription: REX PARTHIS DATUS (“A king has been given to the Parthians”) (RIC II 667–668). Finally, he besieged Hatra late in 116 ce, but the difficulty of the environment and its defenders’ tenacity forced him to lift the siege and return to Antioch (Dio Cass. 68.31). Then ill health intervened, preventing him from campaigning in 117 ce. He put Hadrian in charge of the eastern army and embarked for Rome. En route, he was forced to make landfall at Selinus in Cilicia, where he died (Dio Cass. 68.33).

Fourth Cycle: Lucius Verus to Macrinus (161–217 ce)

The fourth and final cycle of wars lasted from 161 to 217 ce. Two immediate observations must be made with regard to it. First, more than four decades of peace followed Trajan’s death, thanks to his successors, Hadrian (r. 117–138 ce) and Antoninus Pius (r. 138–161 ce). Upon his accession Hadrian promptly abandoned the territory east of the Euphrates, with the exception of Armenia and Osrhoene (SHA, Hadr. 5.1–4; 9.1; Eutr. 8.6; Fest., Brev. 14; 20; Aur. Vict., Caes. 14.1). He clearly saw expansion into the Parthian empire as unfeasible or too costly. As far as we can tell, the Parthians at this stage were satisfied with the Roman pullout. Hence there is no word of Parthian aggression. The Parthians, however, seemed to resume a more aggressive posture during the reign of Antoninus, perhaps under their king Vologases IV (r. 148–192). At this point, they apparently tried to reassert power over Armenia, but Antoninus used diplomacy (in the tradition of Augustus) to persuade him to abandon the enterprise (SHA, Ant. Pius 9.6–7; Marc. 8.6). Peace was maintained.

As for the second observation, even after Parthian-Roman conflict resumed in 161 ce, it had a stop-start rhythm, in which periods of intense war were followed by periods of peace. This pattern raises the question of whether one should consider the period of 161 to 217 ce as a single cycle of war. But there is good reason to do so. The initiator of each episode of war was either a Parthian king who looked to expand Parthian influence into Roman-controlled territories in the full knowledge that this could provoke a destructive Roman campaign, or a Roman emperor who proactively sought out war with the Parthians and targeted their cities. In either case, Trajan must be credited with (or blamed for) providing the inspiration. This string of conflicts should be considered a coherent cycle of war, governed by principles shaped by Trajan.

From the Parthian angle, Trajan showed that the Romans had the inclination and the ability to wreak havoc throughout the whole of Mesopotamia, even in Ctesiphon (contrast to Crassus who had the inclination perhaps, but not the ability). The Parthians were more ready than ever to harm the Roman position in the Near East and to edge the Romans out of the region, when possible. Still they were selective about when they took anti-Roman action. Indeed, they waited for times when the Romans were potentially vulnerable, e.g., during Roman civil war. Still, it is notable that they would take any such action at all, when a retaliatory campaign like Trajan’s remained possible at any time. That indicated a new level of intolerance. The destruction and humiliation inflicted by Trajan left an impression.

From the Roman perspective, Trajan demonstrated that the Romans could invade and harm the Parthian empire at its core. They could reach and take the Parthian capital of Ctesiphon (even if they could not hold it). And, of course, once a Roman emperor took a course of action, it became a potential precedent and source of tradition for the future. One could now claim the conquest of Mesopotamia and its cities, including Ctesiphon, was the normal business of Rome.

The first phase of the fourth cycle lasted from 161 to 166. It was Vologases III (r. 148–192 ce) who introduced it. At a vulnerable point in the principate, the accession of the two new emperors Marcus Aurelius and Lucius Verus in 161 ce, Vologases intervened in Armenia by ousting the Roman candidate Sohaemus and installing the Arsacid Pacorus (SHA, Marc. 8.6; Ant. Pius 9.6–7; Dio Cass. 71.2). When Sedatius Severianus, governor of Cappadocia, responded with an invasion of Armenia, the Parthians defeated him and entered Cappadocia and Syria as well (Dio Cass. 71.2; Oros. 7.15). This led Lucius Verus to mobilize forces and travel east in 162 bce (Dio Cass. 71.2; SHA, Marc. 8.9–14; Verus 6–7). Apparently, he first attempted a diplomatic solution with Vologases, but there are no specific details for this attempted settlement, and in any case, it was rejected (Fronto, Princ. Hist. 14). Instead, he oversaw a campaign lasting several years to reaffirm and expand Roman power in Armenia and Mesopotamia between 163 and 166 ce. First attention was given to Armenia. In 163 ce, Statius Priscus, who had inherited the governorship of Cappadocia from Severianus, invaded the territory, took Artaxata, founded a new city (Kainopolis), and restored Sohaemus (SHA, Marc. 9.1; Dio Cass. 71.3; Fronto, Ad Verum 2.1; see also SHA, Verus 7.1; Lucian, Quomodo Hist. 20). Once again, numismatic evidence of the installation exists (see Figure 2).

Figure 2. Lucius Verus restoring Sohaemus as King of Armenia. Verus places the diadem upon his head with his right hand. The reverse legend reads: REX ARMEN[IIS] DAT[US] (“A king has been given to the Armenians”).

Source: NumisBids.

Then Avidius Cassius, yet another capable (and ambitious) general, spent 164–165 ce campaigning destructively within Mesopotamia. In this case, the Romans took Edessa, Nisibis (which they garrisoned), and Dura Europos (which they held on to), burned Seleucia, and stormed Ctesiphon, destroying Vologases’ summer palace therein (Edessa = Procop., De Bello Persico 2.12.29; Lucian, Quomodo Hist. 22; Nisibis = Lucian, Quomodo Hist. 15; Dura = Lucian, Quomodo Hist. 20, 28; Seleucia and Ctesiphon = Dio Cass. 71.2; see also SHA, Verus 8.1–4; Eutr. 8.10; Oros. 7.15; Amm. Marc. 23.6.23–24). Finally, despite suffering the plague (Dio Cass. 71.2.4; Amm. Marc. 23.6.23–24; Eutr. 8.12; SHA, Verus 8), the Romans managed a military showing in Media in 166 ce as well (SHA, Verus 7.1). The literary sources indicate it was enough to earn Lucius Verus and Marcus Aurelius the titles Armeniacus, Parthicus, and Medicus (SHA, Marc. 9.1–2; Verus 7.2; 7.9). Numismatic evidence supports and refines this picture, providing coins with the titles ARMENIACUS and PARTH(ICUS) MAX(IMUS) (numerous examples among RIC III 498–1504, especially for Lucius Verus).

The second phase was from 193 to 198 ce. Literary sources hint at continued Parthian dissatisfaction and anti-Roman plotting at the time of Avidius Cassius’ bid for imperial power in 175 ce (SHA, Marc. 22.1), but diplomatic contact between Marcus Aurelius and Vologases following Cassius’ demise, maintained peace for a time (SHA, Marc. 26.1). Then, following the reign of Marcus Aurelius and his heir Commodus (r. 180–192 ce) came the year 193 ce, when five Romans sought to hold imperial power: Pertinax, Didius Julianus, Septimius Severus, Pescennius Niger, and Clodius Albinus. Following the failures of Pertinax and Julianus, the senate approved Severus (r. 193–211 ce) as emperor, and he moved east to confront Niger who was governor of Syria and had been acclaimed emperor by his own troops. It was in this context that the Parthians may have looked once again to take advantage of an unstable moment in Roman history. When Niger requested the assistance of the relatively new Parthian king Vologases V (r. 191–207/208 ce) along with that of Armenia (vassal to Rome) and the city of Hatra (independent of Rome), Vologases promised to initiate a muster, but sent no troops as far as the record indicates (Herodian 3.1.2). Instead, it is thought that Vologases urged a rebellion in Osrhoene and Adiabene and their subsequent assault on Nisibis (still in Roman possession) (Dio Cass. 75.1).

Then matters worsened. Osrhoene and Adiabene justified their attack on Nisibis on the grounds that it was in the interests of Severus and offered him the captives and the spoils—but in exchange for a Roman departure from the area and their own independence (Dio Cass. 75.1). Severus refused. He reestablished Roman control of Nisibis, making it a Roman colony, and brought both Osrhoene and Adiabene back into the Roman fold (Dio Cass. 75.2–3; see also SHA, Sev. 18.1 and Herodian 3.9.2, which incorrectly place Osrhoene’s subjugation later in the sequence of events). Next, Vologases and Severus both clearly showed the extent of their hostility to one another. When Severus returned west in 196 ce to eliminate his final competitor (Albinus), Vologases campaigned through northern Mesopotamia, nearly taking Nisibis, and then perhaps moved into Syria (Dio Cass. 76(75.9); SHA, Sev. 15.1–2). Severus then retaliated with his own campaigns in 197–198 ce. In this period, he used his legions to repel the Parthians from Syria (SHA, Sev. 15.1), prompt the submission of the Armenian king (Herodian 3.9.2), invade Mesopotamia and take Babylon and Seleucia (both previously abandoned), and inflict considerable damage on Ctesiphon (Dio Cass. 76 (75.9); SHA, Sev. 16; Herodian 3.9.9–11). He defeated Vologases, stormed the city, set the king to flight, killed great numbers of men, enslaved women and children, and looted the city, in a brutal demonstration of Roman superiority. By this time, it was spring 198 ce, and Severus was short of supplies. So, he departed, going north by the Tigris and besieging Hatra along the way. Unsuccessful in this effort, he tried Hatra again in 199 ce, again (like Trajan) without success (Dio Cass. 75.10–13; see also Herodian 3.9.2–8, who also misplaces this event, but provides details of the siege). Even so, he had demonstrated Roman might in the region and was honored at home with a string of titles: Parthicus, Arabicus, and Adiabenicus (Eutr. 8.18; SHA, Sev. 9.10), all of which are attested on coins, but sometimes appeared as PART(HICUS) ARAB(ICUS) and PART(HICUS) ADIAB(ENICUS) (e.g., RIC IV 55; 62–63; cf. CIL VIII 306). He also took the title Parthicus Maximus, which can be seen on coins and inscriptions as well (RIC IV 122C; CIL III 205; VIII 4543).

As for the third and final phase, it was brought about by Roman aggression. While Severus faced no Parthian resistance after sacking Ctesiphon in 198 ce (an indication perhaps of Parthian weakness), and despite the fact that his successor Caracalla (r. 211–217) encountered no known Parthian provocation, Caracalla still went on the offensive in the Near East. He imprisoned the king of Osrhoene and subdued that territory (Dio Cass. 78(77.12.1)), and he tried to do the same with Armenia, though he failed (Dio Cass. 78(77.12.1–2); 78(77.21)). As for Parthia, Caracalla began preparing a military campaign in 214 ce (Dio Cass. 78(77.18.1), but at the same time he seems to have sought a pretext for the war he desired. Around this time, Parthia was subject to civil strife as two brothers contended for the throne: Vologases VI (r. 207/208–222/223 ce) and Artabanus IV (r. about 213–227 ce). Caracalla demanded in 214 ce that Vologases transfer to Roman custody the Cilician Cynic philosopher Antiochus and a certain Tiridates (Dio Cass. 78(77.19.1)). In the winter of 215/216 ce he asked Artabanus to approve a marriage between his daughter and himself (Dio Cass. 79(78.1); Herodian 4.10). He hoped for a denial that would justify a campaign. While he gained his former request (Dio Cass. 78(77.21)), the results of the latter are less certain. Two main accounts exist for it. First, Herodian suggests Artabanus ultimately agreed and Caracalla used the wedding event at Ctesiphon as an opportunity to ambush the Parthians in 216 ce (4.11). But this ruse sounds fanciful. This is not to say that some engagement in Babylonia was impossible. In fact, another account suggests Caracalla defeated satraps of Artabanus in a disorganized battle in Babylonia (SHA, M. Ant. 6.4). But the second witness, Dio Cassius, reports a more plausible scenario overall. Artabanus refused the marriage proposal, with the result that Caracalla now embarked on his Parthian campaign (79(78.1)). If this is true, then Caracalla failed to engage with Artabanus’ troops and saw instead limited action in Media. In the end, it may be that Caracalla retaliated in a small-scale engagement in Babylonia before traveling north along the Tigris. There he attacked several points in Media, took Arbela, and violated the Parthian royal tombs (Dio Cass. 79(78.1)). As customary, the victories were celebrated with honorific titles, like Parthicus (SHA, M. Ant. 6.5), and were memorialized in coinage, this time with the banner VICTORIA PARTH(ICA) MAX(IMA) (“the greatest victory over Parthia”) (CIL IV 145).

Yet this was not the end of the conflict. By April 217, Artabanus had mobilized a force with which to attack Caracalla. Just as he arrived at the Roman frontier, however, Caracalla was assassinated, and Macrinus (r. 217–218) became emperor (Dio Cass. 79(78.3–5); cf. SHA, M. Ant. 6.6–7.2; Eutr. 20). Macrinus first attempted to negotiate with Artabanus, but he asked for too much: restoration of destroyed settlements, control of Mesopotamia, and compensation for the violation of the tombs (Dio Cass. 79(78.26)). Now both sides were resolved to fight, as it would turn out, one last time. The contest took place outside Nisibis and lasted for three days (Dio Cass. 79(78.26.5–7); Herodian 4.14.1–4.15.9; SHA, Macrinus 2.2; 8.1–4). With the Parthians victorious, negotiation was tried again, and a settlement was reached: Macrinus had to return captives and booty and pay 200 million sesterces as reparation (Dio Cass. 79(78.26.9–78.27.2); Herodian 14.15.7–9; SHA, Macrinus 8.3–4). Though lighter for the Romans than it could have been, the settlement remained a matter of disgrace. But facts mattered less when it came to Roman politics; the confrontation was presented in Rome as a Roman victory and the senate voted for the customary title of Parthicus, though Macrinus refused it (Dio Cass. 79(78.27.3. Coins, too, there were, sporting VICT(ORIA) PART(HICA) (“victory over Parthia”) (RIC IV 166B). Such was the last recorded war between Rome and Parthia.

In reality, there was not much time for another. A revolt in Persis c. 220 ce led to the emergence of the powerful Persian leader Ardashir. This descendant of Sasan conquered and killed Artabanus, c. 227 ce, and eliminated his son Artavasdes shortly after. So perished the Parthian empire and began the Sasanian (Dio Cass. 80(80.3)). The repeated and destructive Roman campaigns no doubt helped to prepare the way for this coup. Ironically, the result was only a more determined enemy of Rome.

The Causes and Significance of the Wars

Frequently Rome and Parthia are presented as two states for whom serious conflict was inevitable. It was only a matter of time before they would collide at the Euphrates. Indeed imperial expansion was an established concept for the Romans by the 1st century bce, and the Parthians’ imperial behavior in the 2nd century bce was reminiscent of the Achaemenids, which may have encouraged them to recreate the Persian empire (see Tac., Ann. 6.31, albeit a later source). Both traditions were powerful forces leading them to a confrontation in the 1st century bce. Tradition was more than influential; it was inescapable.

This expectation has produced a vision of Parthian-Roman history as one on-going conflict lasting more than 200 years. There is comfort in the idea of a fundamental opposition and hostility between Parthia and Rome, which encourages one to notice and emphasize signs of animosity and episodes of bloodshed. In addition, there is little need for differentiation among the incidences of war; they are all symptoms of the same underlying condition: imperialism.

There is truth to this understanding. Imperialism was a real part of the Roman and Parthian worlds—and certainly influential. There also were many moments of tension, disagreement, and/or conflict between Rome and Parthia through the whole history of their relations, as we have seen.

Yet conflict was not entirely inevitable. Accordingly, Parthia and Rome enjoyed lengthy periods of peace. The role of diplomacy deserves mention in connection to these developments. War is one mechanism of intercultural communication and exchange, its most negative form. Diplomacy and the embassies that perform it are another, and they were central to Roman-Parthian relations.

Certainly, and predictably, tension was common in such exchanges. In addition, exchanges sometimes led to increasing alienation, hostility, and war. One such example is the famous exchange between Crassus and Orodes II in the spring of 53 bce (see Plut., Crass. 18.1–2; Dio Cass. 40.16.1–3; Flor. 1.46.4–5; Fest., Brev. 17; Oros. 6.13.2). When asked to explain his aggressive movements across the Euphrates, Crassus said that “He would give his answers in Seleucia.” In response, the Parthian representative pointed to his hand and retorted: “There, Crassus, will hair grow before you will see Seleucia.” The Parthian then insulted Crassus’ greed and imprudence. All this increased the antagonism on both sides. One also could point to embassies between Trajan and Osroes and Parthamasiris, in which Trajan broke with established diplomatic protocols. This dramatic, abrasive, and uncompromising behavior was damaging.

Yet many embassies produced positive and cooperative results. Notable was the decision of Pompey and Phraates III to cooperate in a war against Tigranes the Great of Armenia and, when he was subdued, to decide that the Euphrates would be a shared Roman-Parthian border. Most famous was the diplomatic settlement reached under Augustus and Phraates IV, in which Augustus returned Phraates’ son, and Phraates sent back the standards and captives taken from Crassus. And finally, one must recognize the role of diplomacy between Nero and Vologases I and Tiridates during their war over Armenia in 57–63 ce. In short, the exchanges among the kings, emperor, and their generals as they worked out who should rule Armenia were truly numerous (e.g., see Tac., Ann. 13.9; 13.37; 13.38; 15.5; 15.13; 15.14; 15.17; 15.24; 15.27; 15.28–30; 15.31; Dio Cass. 62.20.4; 62.21.2–3; 62.22.3; 62.23.1–4). From this, one can see how much the Parthians and Romans preferred a diplomatic solution to war. In fact, war in this conflict was a tool of diplomacy. Indeed, already in 58 ce, the Romans advocated the idea of a compromise solution: Rome would be satisfied to approve a Parthian nominee for the Armenian throne (Tac., Ann. 13.34; 13.37). But enough disruption in Roman-Parthian relations already had occurred by this point that both sides needed to demonstrate strength to their respective domestic constituencies. As a result, to ensure the success of a diplomatic solution both sides needed military victories (or at least actions resembling them) to present the desired compromise as a settlement dictated by their own leaders. By 61 ce, Vologases had exhibited enough aggressive behavior, including the limited siege of Tigranocerta, to be ready to adopt the compromise. But it took Nero longer, especially after the defeat and surrender of Paetus in 62–63 ce. His general Corbulo corrected the problem by invading Armenia again and advancing against Vologases and Tiridates. War then had served its purpose. The two parties met, the settlement was fixed, and Tiridates met Nero in Rome. In all of this, diplomacy was the dominant mechanism of intercultural communication, and a stable modus vivendi was the goal.

The coexistence of hostility and cooperation in the history of Rome and Parthia is significant. It compels us to consider further the relationship between these different periods and their specific actions. They are not distributed by chance; there is a pattern to them, governed by principles that reveal something about the characters of these political cultures. In particular, it is useful to distinguish between Parthia and Rome’s practical goals on the ground in the Near East and the image it was necessary to project to their home audiences. In their earliest relations, peace was clearly the goal. At the time of Sulla and Mithridates II, this may simply have resulted from the fact that the territories of the Roman and Parthian empires were not yet in uncomfortably close contact. But in the times of Lucullus, Pompey, and Phraates III, shared interests in the Near East led to tension, but more importantly to cooperation. The curtailing of Pontic and Armenian power led to advances for Rome and Parthia in the Near East. They just needed to work out and coordinate the precise nature of those advances—which they did.

Thereafter, however, the peace was disrupted by the imperialistic demands of Crassus. Hoping to enhance his military reputation, Crassus brought on the first cycle of Roman-Parthian war. His campaign and its aftermath forced the Parthians to carry out incursions into and ultimately a short-lived conquest of Syria and its environs. His defeat by the Parthians, as well as their subsequent aggressive behavior, required Romans like Antony to try to avenge the humiliations with campaigns.

Yet Augustus realized he could resolve the issue otherwise. War was costly and had uncertain consequences. He preferred peace with Parthia. But aware of the importance of a strong public profile in foreign policy, he presented diplomatic gains (particularly the recovery of the standards) to Romans as the result of a Roman victory in a hostile engagement. In the Res Gestae, he claimed that “[he] forced the Parthians to return to [him] the spoils and standards of three Roman armies and to seek as suppliants the friendship of the Roman people” (5.29). On the Prima Porta Augustus, the honorific statue of Augustus as general in military attire, a breastplate displays an image of a Parthian handing over a standard to a representative of Rome. These examples make the association of the standards’ return with a (non-existent) military victory clear. One also might remember how he later mobilized troops to intimidate Phraates V but seems to have taken care to avoid war and reach a peaceful agreement with the king.

This avoidance of direct war, coupled with the maintenance of an image of conflict and victory, then became the Roman strategy for the next century. The one interruption was the second cycle of war under Nero and Vologases. Yet despite direct military engagements, the role of diplomacy and its relationship with war place it more in the tradition of Augustus. These events also demonstrate that the Parthians pursued the same strategy: seek peace in general but take action in ways fostering the image of war and Parthian victory. This was surely a significant factor in their interventions in Armenia, but willingness to accept a compromise with Rome. It was an effective approach.

Still, an underlying problem existed. The strategy continued to condition one’s domestic constituency to accept and expect an aggressive policy. The conditioning then created circumstances favorable to an emperor or king who wished to make the image of war a serious reality. This is exactly what Trajan did. He wished to complete his successful imperial career with an unmatched victory over Parthia, so he introduced the third cycle of war and brought Roman forces to Ctesiphon. This in turn paved the way for the fourth cycle of war, in which the Arsacids were more willing to demonstrate the vulnerability of Roman power in the Near East and to harm it, while the Roman emperors followed Trajan’s steps deep into Mesopotamia and took measures destructive to the Parthian empire’s cities and stability. In this way, Trajan worked with pre-existing Roman tradition, but reshaped it. The new tradition affected Parthians and Romans alike. In it was the danger of creating images of hostility between the ancient West and Middle East. One day’s image became another day’s reality.

Discussion of the Literature

The ancient evidence for Parthian-Roman wars is fragmentary and comes largely (though not exclusively) from the Greco-Roman literary tradition. (For discussion of the source tradition, an understanding of which is vital for anyone with a serious interest in Parthia, see: Boyce; Widengren; Wiesehöfer; Hackl, Jacobs, and Weber; Dąbrowa; Potts).2 As a result, the initial major studies on the subject are within monographs aiming to assemble the scattered source material to create a narrative history of Parthia and its empire. Rawlinson carried out the earliest such attempt.3 The classic study, however, is that of Debevoise, who meticulously cites the ancient sources.4 Later attempts have provided updated and useful syntheses, such as those of Shippmann and Bivar,5 but Debevoise’s work remains unsurpassed. With the groundwork laid by these scholars, others have focused on particular aspects of Parthian history. Many, for example, have addressed squarely the confrontation of Rome and Parthia, and they have done so from various angles. Particularly superb among them is Ziegler, who considers Roman-Parthian relations, and the conflicts that were a part of them, in context of international law.6 Also impressive and with broader focus on Roman foreign policy (including relations with Parthia) more generally are Sherwin-White and Linz.7 Campbell also provides a useful survey of the issue that focuses on the significance of diplomacy.8 For military history specifically, Sampson and Sheldon stand on the shoulders of Debevoise’s research, but they offer well-researched and well-presented studies.9 In addition, they provide readers with two distinctive approaches to the subject. Sampson emphasizes the incompatibility of and hostility between the Roman and Parthian empires and thereby concludes that their conflict was inevitable. Sheldon highlights more constructive elements in their relationship, particularly when it came to Parthian interests in peace. Both agree (and there is broad consensus on the point) that Rome was the more aggressive of the two states overall. Of these two studies, Sheldon has produced the more comprehensive, covering the full sweep of the Parthian-Roman wars. There are also scholars who cover particular phases in the conflict (sometimes from angles that go beyond the military).10 Some have focused on specific territories relevant to the Roman-Parthian conflict, such as Chaumont, who investigates the significance of the territory of Armenia.11 On a final note, highly pertinent and significant are studies that appreciate the Parthian perspective and imperial motivations in more depth, such as those of Wolski and Shayegan, which concern themselves especially with the Achaemenid program of the Parthians and its implications for Parthian imperialism and military activity.12 These studies have inspired additional work on mechanisms of intercultural communication between the Arsacids and Romans, such as the role of Achaemenid and Hellenistic precedents, the embassy, and local elites in the Parthian-Roman borderland, as exemplified in Schlude and Rubin.13


  • Bengtson, Hermann. Zum Partherfeldzug des Antonius. Munich: Bayerische Akademie der Wissenschaften, 1974.
  • Bivar, Adrian D. H. “The Political History of Iran under the Arsacids.” In The Cambridge History of Iran, Vol. 3: The Seleucid, Parthian and Sasanian Periods. Edited by Ehsan Yarshater, 21–99. Cambridge, UK: Cambridge University Press, 1983.
  • Bucheim, Hans. Die Orientpolitik des Triumvirn M. Antonius. Heidelberg, Germany: Carl Winter Universitätsverlag, 1960.
  • Bühler, Daniel. Macht und Treue: Publius Ventidius: Eine römische Karriere zwischen Republik und Monarchie. Munich: Allitera Verlag, 2009.
  • Campbell, J. Brian. “War and Diplomacy: Rome and Parthia, 31 BC–AD 235.” In War and Society in the Roman World. Edited by John W. Rich and Graham Shipley, 213–240. New York: Routledge, 1993.
  • Chaumont, Marie-Louise. “L’Arménie entre Rome et l’Iran: de l’avènement d’Auguste à l’avènement de Dioclétien.” Aufstieg und Niedergang der römischen Welt 9, no. 1 (1976): 71–194.
  • Dąbrowa, Edward. “The Arsacid Empire.” In The Oxford Handbook of Iranian History. Edited by Touraj Daryaee, 164–186. Oxford: Oxford University Press, 2012.
  • Debevoise, Nielson Carel. A Political History of Parthia. Chicago: The University of Chicago Press, 1938.
  • Gilmartin, Kristine. “Corbulo’s Campaigns in the East: An Analysis of Tacitus’ Account.” Historia 22, no. 4 (1973): 583–626.
  • Hackl, Ursala, Bruno Jacobs, and Dieter Weber, eds. Quellen zur Geschichte des Partherreiches: Textsammlung mit Übersetzungen und Kommentaren. Göttingen, Germany: Vandenhoeck and Ruprecht, 2010.
  • Hammond, Mason. “Corbulo and Nero’s Eastern Policy.” Harvard Studies in Classical Philology 45 (1934): 81–104.
  • Lepper, Frank A. Trajan’s Parthian War. London: Oxford University Press, 1948.
  • Linz, Oliver. Studien zur römischen Ostpolitik im Principat. Hamburg: Verlag Dr. Kovač, 2009.
  • Potts, Daniel T., ed. The Oxford Handbook of Ancient Iran. Oxford: Oxford University Press, 2013.
  • Rawlinson, George. The Sixth Great Oriental Monarchy: Geography, History, and Antiquities of Parthia. London: Longmans, Green, 1873.
  • Sampson, Gareth C. The Defeat of Rome: Crassus, Carrhae, and the Invasion of the East. Barnsley, UK: Pen and Sword Military, 2008.
  • Schlude, Jason M. “The Parthian Response to the Campaign of Crassus.” Latomus 71, no. 1 (2012): 11–23.
  • Schlude, Jason M., and Benjamin B. Rubin, eds. Arsacids, Romans, and Local Elites: Cross-Cultural Interactions of the Parthian Empire. Oxford: Oxbow Books, 2017.
  • Shayegan, M. Rahim. Arsacids and Sasanians: Political Ideology in Post-Hellenistic and Late Antique Persia. Cambridge: Cambridge University Press, 2011.
  • Sheldon, M. Rahim. Rome’s Wars in Parthia. London: Vallentine Mitchell, 2010.
  • Sherwin-White, Adrian Nicholas. Roman Foreign Policy in the East, 168 BC to AD 1. London: Duckworth, 1984.
  • Shippmann, Klaus. Grundzüge der Parthischen Geschichte. Darmstadt, Germany: Wissenschaftliche Buchgesellschaft, 1980.
  • Traina, Guisto, and Gerard Marino. Carrhes, 9 juin 53 av. J.-C.: Anatomie d’une défaite. Paris: Les Belles Lettres, 2011.
  • Weggen, Katharina. Der lange Schatten von Carrhae: Studien zu M. Licinius Crassus. Hamburg: Kovač, 2011.
  • Wiesehöfer, Josef, ed. Das Partherreich und seine Zeugnisse. Stuttgart: Franz Steiner Verlag, 1998.
  • Wolski, Josef. L’empire des Arsacides. Leuven, Belgium: E. Peeters, 1993.
  • Ziegler, Karl-Heinz. Die Beziehungen zwischen Rom und dem Partherreich: Ein Beitrag zur Geschichte des Völkerrechts. Wiesbaden, Germany: Franz Steiner Verlag, 1964.