The Parthians were also masters of the art of war, as they would show in the next period of conflict, with Rome. Driven on to ever-wider conquests by the ambitions of mighty patricians like Pompeii, Lucullus, and Crassus, leaders who saw conquest and military glory as necessary adjuncts to a successful political career, the Roman republic by the first half of the first century BC had taken over the eastern Mediterranean from its previous Hellenistic overlords and had begun to press even farther eastward. The Romans’ main area of conflict with the Parthians was in Armenia, Syria, and northern Mesopotamia.
In 53 BC Marcus Licinius Crassus, a fabulously rich Roman politician who had destroyed the slave revolt of Spartacus in southern Italy in earlier years, became the new governor of Roman Syria. Hoping to make conquests in the east to rival those recently achieved by Caesar in Gaul, Crassus marched an army of some forty thousand men east to Carrhae (modern Harran)—arrogantly rejecting the advice of the king of Armenia to take advantage of his friendship and follow a less exposed northerly route. At Carrhae Crassus’s army was met in the open plain by a smaller but fast-moving force of about ten thousand Parthian horsemen, including large numbers of horse archers, supported by a much smaller force of heavily armored cavalrymen on armored horses, each man wielding a long, heavy lance. The Roman force was composed primarily of armored infantry equipped with swords and heavy throwing spears, along with some Gaulish cavalrymen who were either lightly armored or not armored at all.
The Parthians confronted Crassus with a kind of fighting that the Romans had not previously encountered, and against which they had no answer. The Roman infantry advanced, but the Parthian horse archers withdrew before them, circling around to shoot arrows into the flanks of their column. Hour after hour the arrows rained down on the Romans, and despite their heavy armor the powerful Parthian war bows frequently zinged an arrow past the edge of a shield, found a gap at the neck between body armor and helmet, punched through a weak link in chain mail, or wounded a soldier’s unprotected hands or feet. The Romans grew tired and thirsty in the heat, and their frustration at not being able to get to grips with the Parthians turned to defeatism, especially when they saw the Parthians resupply themselves with arrows from masses of heavily laden pack camels.
At one point Crassus’s son led a detachment, including the Gaulish cavalry, against the Parthians. The Parthians pulled back as if in disorder, but their real intention was to draw the detachment away beyond any possible assistance from the main body. When the Gauls rode ahead to chase off the archers, the Parthian heavy cavalry charged down on them, spearing the lightly armored Gauls and their horses with their long lances. In desperation, the Gauls tried to attack the Parthian horses by dismounting and rolling under them, trying to stab up at their unprotected bellies, but even this desperate tactic could not save them. Then the full strength of the Parthian horse archers turned on the Roman detachment. More and more of them were hit by arrows, while all were disoriented and confused by the clouds of dust thrown up by the Parthians’ horses. Crassus’s son pulled his men back to a small hill—where they were surrounded and eventually killed, with the exception of about five hundred, who were taken prisoner.
The defeat of the detachment and the jubilation of the Parthians further demoralized the main Roman force. Finally, Crassus attempted to negotiate with the Parthian general, Suren, only to be killed in a scuffle and beheaded. The survivors of the Roman army withdrew in disorder back into Roman Syria. Meanwhile, as many as ten thousand Roman prisoners were marched off by the Parthians to the remote northeast of the empire.
According to the Greek historian Plutarch the head of Crassus was sent to the Parthian king, Orodes, and it arrived while the king was listening to an actor delivering some lines from Euripedes’s play The Bacchae. To the applause of the court, the actor took the head and spoke the words of Queen Agave of Thebes, who in the play unwittingly killed her own son, King Pentheus, while in a Bacchic trance:
We’ve hunted down a lion’s whelp today,
And from the mountains bring a noble prey
Some have suggested that the Parthian general, recorded in the Western sources as Suren, was the warrior-hero later remembered as Rostam and immortalized in the revered tenth-century Persian poet Ferdowsi’s Shahnameh (Book of Kings). Like Rostam, Suren hailed from Sistan (originally Sakastan—the land of the Sakae), and like Rostam, he also had a troubled relationship with his king. Orodes was so resentful of Suren’s victory that he had him murdered.
The defeat at Carrhae was a great blow to Roman prestige in the east, and after it the Parthians were able to extend their control to include Armenia. But in the fiercely competitive environment of Rome toward the end of the republic, the defeat, humiliation, and death of Crassus were a challenge as much as a warning. To succeed where Crassus had failed—to win a Parthian triumph—became an inviting political prize. Another incentive was the wealth of the silk trade. While the hostile Parthians controlled the central part of the route to China, wealthy Romans were dismayed to see much of the gold they paid to have their wives and daughters clothed in expensive silks going to their most redoubtable enemies.
The next Roman to test the Parthians in a major way was Mark Antony. But between the expeditions of Crassus and Antony, the Parthians and the Romans fought several other campaigns, with mixed outcomes. In 51 BC some Roman survivors from Carrhae ambushed an invading Parthian force near Antioch and destroyed it. But in 40 BC another Parthian force, commanded by Orodes’s son Pacorus (with the help of a renegade Roman, Quintus Labienus), broke out of Syria and conquered both Palestine and most of the provinces of Asia Minor. Exploiting the chaos of the civil wars that followed the murder of Julius Caesar in 44 BC, the Parthian invaders received the submission of many towns without a siege. But a year or so later Publius Ventidius, one of Mark Antony’s subordinates, rescued the eastern provinces with some of the veteran legions of Caesar’s army. He defeated the Parthians in a series of battles in which all the main Parthian commanders were killed, including Pacorus and Labienus. Back in Rome, Ventidius’s triumph over the Parthians was considered a rare honor. Seeing his lieutenant so praised, Mark Antony wanted the glory of a victory against the Parthians for himself.
In 36 BC he took an army more than double the size of that of Crassus into the same area of upper Mesopotamia. Antony soon encountered many of the same difficulties that had frustrated Crassus. The Romans found that their best remedy against the Parthian arrows was to form the close formation called the testudo (tortoise), in which the soldiers closed up so that their shields made a wall in front, with the ranks behind holding their shields over their heads, overlapping, to make a roof. This made an effective defense but slowed the army’s advance to a crawl. The Roman infantry still could not hit back at the Parthian horse archers, whose mobility enabled them to range at will around the marching Romans and attack them at their most vulnerable. The Parthians were also able to attack Antony’s supply columns, and the difficulty of finding food and water made the large numbers of the invading force a liability rather than an asset. Having suffered in this way in the south, Antony attempted a more northerly attack on Parthian territory, penetrating into what is now Azerbaijan. But he achieved little, and was forced to retreat through Armenia in the winter cold, losing as many as twenty-four thousand men.
Antony saved some face by a later campaign in Armenia, but the overall message of these Roman encounters with the Parthians was that the styles of warfare of the opponents, and the geography of the region, dictated a stalemate that would be difficult for either side to break. The Parthian cavalry was vulnerable to ambush by Roman infantry in the hilly, less open terrain of the Roman-controlled territories, and lacked the siege equipment necessary to take the Roman towns. At the same time, the Romans were vulnerable to the Parthians in the open Mesopotamian plain and would always find it difficult to protect their supply lines against the more mobile Parthian forces. These factors were more or less permanent.
Perhaps recognizing the intractability of this situation, after Augustus eventually achieved supremacy in the Roman Empire and ended the civil wars by defeating Mark Antony in 31/30 BC, Augustus followed a policy of diplomacy with the Parthians. In this way he was able to retrieve the eagle standards of the legions that had been lost at Carrhae. The Parthians seem to have used the period of peace in the west to create a new Indo-Parthian empire in the Punjab, under a line descended from the Suren family. But the wars in the west began again in the reign of Nero, after the Parthian king Vologases I (Valkash) had appointed a new king in Armenia, which the Romans regarded as a dependent state of the Roman Empire. The general Gnaeus Domitius Corbulo conquered Armenia in AD 58–60, but the Parthians counterattacked with some success thereafter, capturing a Roman force. It has been suggested that the Roman armor made of overlapping plates (lorica segmentata), familiar from films and children’s books, was developed as a counter to Parthian arrows around the time of the campaign of Corbulo. The outcome of the Armenian war was that the Romans and Parthians signed a treaty agreeing to the establishment of an independent Arsacid dynasty in Armenia as a buffer state, but with the succession subject to Roman approval.
Vologases I may also be significant in the history of Mazdaism and the beginnings of its transition into the modern religion of Zoroastrianism. Later Zoroastrian texts say that a king Valkash (they do not specify which one—several Arsacid kings took that name) was the first to tell the Magian priests to bring together all the oral and written traditions of their religion and record them systematically. This began the process that, several centuries later, led to the assembly of the texts of the Avesta and the other holy scriptures of Zoroastrianism. If indeed it was Vologases I who gave out those instructions (a conjecture supported by the fact that his brother Tiridates was known also for his Mazdaean piety8), it would perhaps fit with other decisions and policies during his reign, which seem consistently to have stressed a desire to reassert the Iranian character of the state. Vologases I is believed to have built a new capital named after himself near Seleuceia and Ctesiphon, with the aim of avoiding the Greek character of those places. Some of his coins were struck with lettering in Aramaic script (the script in which the Parthian language was usually written) rather than in Greek, as had been the case before. And there are suggestions also that he was hostile to the Jews, which was atypical in the Arsacid period. Although his immediate successors did not follow through with all of these novelties, they do prefigure the policies of the Sassanids. The gradual erosion of Greek influence and the strengthening of Iranian identity are features of the reigns after Vologases I.
The Parthian army was an especially interesting combination of the very heaviest and very lightest types of cavalry. The nobles were cataphract lancers, protected from head to toe in strong metal armour and mounted on big horses which were also completely armoured in metal except for their legs. They neither needed or carried a shield. Their primary weapon was the 12 feet long Kontos, a heavy lance with a broad heavy head that could penetrate a horse’s chest from its weight alone or cut off a man’s head. The rest of the cavalry were horse archers, unarmoured, unshielded, armed only with bow and knife, and relying on their horse’s speed to keep them out harm’s way. The proportions of these could vary greatly. At Carrhae in 53 B. C., there were 1,000 cataphracts to 10,000 horse archers. At Taurus in 39 B. C., a large force of cataphracts was supported by a considerably smaller number of horse archers, while Marcus Antonius was opposed in 36 B. C. by 50,000 horse archers but relatively few cataphracts
Cataphracts could ride over any cavalry that tried to meet them, but could not usually catch lighter horsemen that threw or shot missiles at them, then evaded their charge by galloping away. However, they were pretty well invulnerable to such missiles. They could not count on breaking steady close formation infantry in sufficient depth, but would probably break them if they were disordered, wearied or demoralised by a long period of shooting by the horse archers.
Horse archers could not be caught by infantry, but could be chased off by light cavalry if there were insufficient cataphracts to protect them. They were at a disadvantage against javelin armed cavalry at short range, because, unlike their opponents, they could not use shields. They could pursue and shoot at cavalry that evaded away from the cataphracts as long as they were careful not to go too far. They could not destroy an infantry force on their own, but could cause a constant trickle of casualties from arrows that were not intercepted by the defenders’ shields and in time wear down their morale. A lucky burst of arrows at close range might occasionally produce a weak point that could be exploited by a cataphract charge.
While cataphracts and horse archers always formed the great majority of a Parthian army, other troop types were occasionally used. Small numbers of light infantry with bows were occasionally put into the field if operating in friendly territory, and in 217 A. D., cataphract camels were tried but proved relatively unsuccessful.
The most successful of a large number of Parthian confrontations with Rome was the first one. As with the Gemans, the best known battle is the sole Roman disaster, the Carrhae campaign of 53 B. C. The Romans did much better on later occasions, mainly because they learned by their mistakes, but partly because the Parthian balance between cataphracts and horse archers was often less ideal.
The most obvious disadvantage of a Parthian army against Romans was that it was too weak in infantry to operate successfully in mountain or forest country. This was not a great help to Romans invading Parthia, except that they could cut down their vulnerability by going the long way round through Armenia and putting off the inevitable meeting in open country to a later stage of the invasion. However, the Parthians had to be very careful which bits of Roman territory they invaded! They also lacked the infantry and artillery to successfully besiege a Roman fortress or city. A related but less obvious disadvantage is that a horse that has been ridden all day has to rest and graze at night. A Parthian night camp was more than once demonstrated to be extremely vulnerable to a Roman night attack. To be safe, the Parthians had to retire a night’s infantry march from the Romans each evening. This prevented the close blockade of a city and often meant that they had to spend the next morning looking for a Roman army they had mislaid during the night.
Another well learned lesson was that cavalry should not pursue horse archers too far. A short controlled charge could keep them out of effective range and occasionally net an overconfident straggler. Get out of reach of the main body, and you would be rolled over or forced to flee by cataphracts and shot to pieces by a swarm of quickly reversing horse archers. Another way of keeping the horse archers at a distance was to have a sizeable proportion of missile armed light infantry. Slingers were especially valuable, because they were the only troops that could make much impression on distant cataphracts. A lead slingshot could concuss or bruise the most heavily armoured man.
Formations were also important. Infantry had to be at least eight ranks deep to hold a cataphract charge, and it was essential that the enemy was not allowed into anyone’s rear. Luckily, the open terrain that made Parthians dangerous also made it possible for the army to march in a hollow square with the baggage train inside. A close control was necessary, since if the rear face had to turn to meet attack and the front continued to march on, the defensive integrity would be hopelessly compromised Caltrops were a partial answer to cataphract charges. These were small spiked objects so designed that when tossed on the ground one spike was always uppermost. They were especially useful against cataphract camels as camels have soft feet instead of hoofs.