Left: East Parthian Cataphract; Middle: Parthian Horse-Archer; Right: Parthian Cataphract from Hatra
As the Roman army began its march down the east bank of the Euphrates, the forward scouts reported that the cavalry tracks of horse-riders had been sighted. They reasoned that these had been made by enemy cavalry retreating back into the nearby desert. Although Crassus was again warned not to proceed by Armenian envoys, he took advice from an Arab leader named Ariamnes who recommended immediate pursuit. Crassus marched his army into the desert without adequate water supplies or suitable cover from the scorching summer sun. Plutarch describes a landscape that had ‘no branches, streams, hillocks or greenery, just an expanse of sand which might encompass the army’. After hours of marching, the Roman army sighted a force of several thousand Parthian cavalry. At first the Roman army tried to extend their ranks into a long defensive line, before new orders were issued and the legions drew into tight infantry blocks and prepared to engage the mounted enemy.
Surenas placed part of his army in front of the Romans, assembling them in a formation that concealed their full numerical strength. The cataphracts hid their bright armour beneath animal skins and dull leather cloaks, so that the Romans would be unprepared for an assault by heavy cavalry. Crassus appeared to be engaging a weaker enemy force, but as the Romans advanced, Surenas gave a signal to mounted drummers in the Parthian line. They began to rhythmically pound the large hide-skin drums fixed to their horses. These drums were hung with bronze bells and produced a deep reverberating tone that filled the desert plain with a roaring sound like the approach of wild animals, or an oncoming thunderstorm. This noise caused fear and alarm in the Roman ranks. The resultant tumult made it difficult for Roman forces to convey orders along their battle-line. Breaking into a canter the Parthian formation began to spread out along the plain, then charged forward in a full gallop towards the legions. At this moment Surenas signalled his cataphracts to discard their dark coverings and reveal the full splendour of their encompassing armour. The Romans suddenly saw the gleam of polished armour plates and the steel of the enemy lances. As the Parthians began their charge forward, they unfurled colourful banners made from a strange ethereal fabric that streamed out behind them in the desert breeze. This was said to be the first time that Roman soldiers had seen Chinese silk.
The legionaries had formed themselves into dense infantry squares to resist the cavalry charge, but the Parthian horsemen suddenly broke off the attack before they reached the Roman line. They paced along the front ranks keeping their distance from the legionaries. The cataphracts were screening a larger force of Parthian archers who rode the length of the Roman lines, firing lethal volleys of arrows into the densely packed legionary formations. These Parthian bows outranged the Roman javelins which were one-shot weapons designed to buckle and break on impact so that they could not be reused by the opposition. There were a few units of Roman archers with the legions, but they did not have the numbers or weapon range to match the powerful bows of the fast-moving Parthian riders.
The Romans raised their shields and held them together in a shield-wall formation known as the testudo (the tortoise). The front ranks interlocked their shields into an outer barrier, while the inner rows lifted their shields above their heads to create a shell-like roof designed to deflect missile fire. But the piercing steel of the Parthian arrows punched through their wooden shields and tore through their chain mail chest armour.
Crassus ordered his Roman skirmishers to charge the Parthian horsemen, but the lightly-armoured auxiliary troops were driven back into the legionary ranks by a dense hail of arrows. As they scrambled for protection, they caused further fear and disorder amongst their fellow soldiers. Riding around the Roman positions, the Parthians spread out into a wide formation and shot their arrows into the legionary ranks from multiple quarters. These highly skilled warriors could fire on the gallop and wheel around in the saddle to shoot at targets behind them – a manoeuvre known as the ‘Parthian shot’. Any of the legionary ranks who tried to charge the Parthian archers found that the enemy fled before them, maintaining their distance, but still firing to the rear at their now exposed pursuers.
By this stage it was clear to the Roman officers that the Parthians were equipped with a superior form of weaponry that was causing unexpectedly high casualty rates amongst the legionaries. But Crassus still expected the enemy either to withdraw, or commit to decisive close-quarter combat once their arrows were exhausted. Close combat would favour the Romans with their superior numbers and proven expertise in brutal short-range engagements. However, this hope was thwarted when Roman observers realised that Parthian archers who had emptied their quivers were returning to the front line fully restocked. Heavily laden camel teams were carrying new bundles of the lethal, steel-tipped arrows into the offensive.
The fake retreat was a well-known tactic in steppe warfare, used to divide and exhaust any over-eager enemy cavalry. In 120 BC the Han general Li Guang faced similar strategies when he fought mounted Xiongnu warriors in Mongolia. In response, he placed his son Li Gan at the head of a small cavalry unit with orders to charge towards the enemy and provoke the expected feigned retreat. Li Gan galloped out from the Chinese ranks and when the opposing horsemen fled towards their ambush site, he returned immediately to the main army. This allowed his father to boost Chinese moral by proclaiming the Xiongnu to be ‘cowards’.
The Parthians expected the Romans to be unfamiliar with this tactic. When Crassus realised there would be no imminent end to the Parthian missile fire he ordered an assault using the Roman cavalry he had kept in reserve. He sent his own son Publius to lead the breakout in command of Caesar’s mounted Gallic auxiliaries. Publius was a popular figure amongst the troops and as he rode through the front ranks of the Roman army, a large section of the surrounding infantry ran forward to support his assault. At that moment the Parthian horsemen suddenly wheeled around and fled the battlefield in what appeared to be full-scale rout. The Roman cavalry pursued them with several thousand infantry joining the headlong rush after the fleeing enemy. This forward charge took the cavalry far from the sight of Crassus and the protection of the main Roman army. Publius did not realise that he was entering a trap until the retreating Parthians wheeled around to face their pursuers and were joined by further battle-lines of steppe horsemen. Surenas had prepared a killing-ground some distance from the first battle site where the larger part of his army of 10,000 warriors waited to ambush and slaughter the most mobile units of the Roman army.
Outnumbered and exhausted, the Roman infantry formed a wall of shields around Publius in an attempt to protect the cavalry. The Parthians rode around this isolated force launching volleys of arrows into the huddled mass. Their horses’ hooves tore up the bare earth until a great cloud of choking dust engulfed the Romans and made it difficult for their officers to shout commands. The Romans were cut off from any retreat and their officers could not restore cohesion. After the haphazard chaos of the pursuit, intermixed divisions clambered through their own ranks to escape the unrelenting arrow fire. The battlefield was covered in low hillocks wich made it difficult for the Roman troops to form an effective shieldwall or assemble into rank formations. Publius urged his soldiers to charge forward into the enemy, but his infantry were already critically injured, their hands pinned to their shields by Parthian arrows, or their feet skewered to the ground. To some, these injuries may have been reminiscent of crucifixion, the humiliating public death that Crassus had imposed upon the slave-captives who had supported the Spartacus rebellion.
When it was clear that no reinforcements would come to their aid, Publius led a final desperate cavalry charge out from the Roman ranks to engage the enemy in close-quarter combat. But his lightly-equipped Gauls were no match for the armour-encased cataphracts with their heavy steel-tipped lances. In desperation, those Gallic riders who had been thrown from their saddles tried to stab at the unprotected underbelly of the cataphract horses, only to be trampled to death in the attempt. The Gauls were quickly exhausted by thirst and the oppressive desert heat. Consequently only a few survivors managed to retreat back into the Roman infantry ranks, carrying with them the critically wounded Publius.
Crassus still had more than 30,000 legionaries, but when the news came of the enemy ambush, he was overcome with conflicting emotion and could not decide on a course of action. By ordering an immediate advance to the new battle site he might have saved Publius, but this meant jeopardising the entire army. An urgent retreat back to the Euphrates would have condemned the Gallic cavalry to annihilation, but might have granted the main army enough time to escape. Crassus stalled and waited, before ordering his army forward to rescue Publius and the Roman cavalry. But by then it was already too late.
As Parthian arrow-fire continued, the encircled Romans commanded by Publius realised that there was no possibility of rescue or further resistance. Many of the leading Roman officers began to commit suicide rather than face the ignominy of defeat. Those suffering multiple wounds were assisted to die by junior colleagues. Publius, who had his sword hand pierced by an arrow, had to be helped by his shield-bearer to force the blade into his own chest. When the Romans could no longer maintain their rank order amidst their crippled and dead comrades, the cataphracts charged, trampling the fallen and skewering the legionaries with their long-lances. Almost 6,000 Roman troops were butchered on the battlefield before Surenas called a halt to the killing and prepared his army to engage Crassus and the main Roman force.
As the full Parthian army rode into view, they sounded their drums and spread out into a wide formation to relaunch their attack on the main Roman force. They galloped close to the Roman ranks and displayed the severed head of Publius to the horrified legionaries. Then with jeering insults they resumed their relentless arrow-fire. Without the support of the cavalry the Roman retreat back to the Euphrates Valley would involve hours of marching through dry featureless terrain with the infantry exposed to continuous missile attack. The Romans were forced to abandon any immediate prospect of retreat and formed ranks into infantry squares to withstand the Parthian arrows.
From that moment on, any Roman units who broke formation or tried to rush into close combat with the Parthian archers were charged by the cataphracts. These cataphracts could impale more than one man with a single powerful strike from their long steel lances and their manoeuvres forced the Roman ranks back into tightly packed formations. This maximised the impact of the Parthian archery volleys and caused greater distress and trauma to troops already crushed in by their comrades, or choked by dust. Stumbling over corpses, some legionaries succumbed to heat-stroke and exhaustion. Others caused themselves further injuries by tearing out the barbed steel arrowheads from their wounded bodies.
In 101 BC, the Han general Li Ling had found himself in a similar situation against the Xiongnu. His small regiment had fought a disciplined retreat across the Mongolian steppe while being harassed by an overwhelming force of Xiongnu horsemen led by their Chanyu. When the Chinese troops had exhausted their arrows, Li Ling destroyed and buried his battle standards rather than have them fall into enemy hands. Then he waited until dusk and created a diversion that allowed many of his remaining soldiers to escape back to the well-guarded Chinese frontier.
By contrast, as night fell Crassus had been reduced to utter despair before the Parthians finally broke off their attack due to fatigue and poor visibility. Centurions took charge of the situation and prepared their units to retreat in silence under the cover of darkness. They abandoned any wounded soldiers who could not keep pace, but when their colleagues began to shout out appeals for help, this caused widespread alarm. The retreating force was thrown into confusion by the fear of further Parthian attacks and they fled in disarray to a nearby fortified town named Carrhae. Carrhae had a sympathetic Greek population and a Roman garrison, but this outpost was not provisioned to withstand a protracted siege. The following night Crassus escaped the town with his command staff in the hope of finding safety in Syria or Asia Minor. The remaining Roman troops took their chances to leave the town in small groups setting out at nightfall to evade the Parthian cavalry and their Arab allies, who were patrolling the surrounding countryside ready to kill or capture any survivors.
But before Crassus could reach the Mediterranean coast, the Parthians caught up with him. The general was compelled by his own troops to go forward and meet the enemy and discuss terms. When the Parthians tried to seize Crassus, there was a violent scuffle with his bodyguards and the general was fatally stabbed. The battle-standards of the legions defeated at Carrhae were taken to Ctesiphon as trophies and Surenas sent the severed head of Crassus to the Parthian King Orodes in Armenia. The Parthians believed that Crassus had been motivated by plunder and it was said that they poured melted gold into the mouth of his severed head as a symbol of his greed.
From an army of 40,000 Roman troops less than a quarter were able to reach safety. More than 20,000 men were killed and 10,000 legionaries were taken prisoner. This was the greatest loss of men that the Romans suffered in a single battle and the largest number of citizen-soldiers ever captured by a foreign regime. The entire episode demonstrated how devastating steppe tactics and weaponry could be when used against unprepared infantry.
The Crassus campaign had taken almost all the available Roman troops out of Syria, so the Parthians were able to plunder the region and claim full control of Armenia. Prince Surenas exploited his victory at Carrhae to reinforce Parthian authority in Babylonia. He prepared a parade through Seleucia that further humiliated the Romans by imitating an imperial triumph. The procession was complete with prisoners of war and military trophies, including the legionary battle-standards captured during the retreat. One Roman captive who resembled Crassus was forced to wear a woman’s purple dress to mock the appearance of a triumphal toga. He was accompanied by a guard of prostitutes and musicians who ridiculed Roman courage and battle prowess. This exhibition sent a powerful message to the Greeks of Babylonia that Parthia was the military superior of Rome. After this degradation, the surviving Roman prisoners were taken to be settled at Merv on the eastern frontier of the Parthian realm (Margiana in modern Turkmenistan). Rather than conquerors of the east, they had become prisoners in exile on the borders of the steppe far from their Mediterranean homelands.