'He'll talk. If the fool doesn't,' replied Brennus calmly, 'the entire army will rise up.'

The Gaul was right. Crassus finally realised that his soldiers had suffered enough. The racket alone would have conveyed their depth of anger and it was not long before a party detached itself from the centre. Led by the swarthy Andromachus, Crassus and his legates rode across the sand towards the waiting Parthians, their heads bowed. Even the horsehair plumes on the officers' helmets were sagging. Not a sound broke the silence as the sun beat down on the dramatic scene. Motionless, the archers sat high above. Watching. Waiting. Ready to attack.

For some time the two groups talked, their words inaudible because of the distance. With Andromachus acting as interpreter, Crassus and his officers listened to Surena's terms.

Romulus clenched his jaw. 'Let's hope that the fool gets us a safe pass, or we will all be food for vultures.'

'They will be wanting guarantees that he won't invade again,' said Tarquinius.

'What kind?' asked Romulus.

Brennus spat on the hot sand. 'Prisoners.'

The young man's stomach lurched. Was this what Tarquinius had meant? Romulus had no time to dwell on the disconcerting thought.

Above them, a vicious melee suddenly broke out. Andromachus and the Parthians had produced concealed weapons and killed three legates. While the soldiers watched helplessly, Crassus was knocked from his horse with a blow to the head. Instantly two warriors jumped down and threw his senseless body on to a horse. Leaving their companions to finish off the remaining Romans, they galloped away up the dune.

The stunned legionaries watched as their sole chance of salvation disappeared. One senior officer had managed to pull his horse around and ride back, but the others lay lifeless on the sand.

The army had been left with only one legate.

'We are done for,' groaned a voice nearby.

Brennus drew his longsword, his face calm.

'Treacherous bastards,' said Romulus bitterly.

'They must have been planning it all along,' remarked Tarquinius. 'That I did not see.'

The horsemen above had already split into two files, each aiming at one side of the Roman column. Surena had prepared the final blow.

Romulus pulled his gladius free, regretting that he would never get revenge on Gemellus. They would be lucky to survive the next hour.

Then Tarquinius glanced at the sky and to his relief, spoke with absolute certainty. 'We three will not die today.' He lowered his voice. 'Many will. But not us.'

A great gust of relief escaped Romulus' lips.

Brennus grinned from ear to ear, his faith stronger than ever.

There was a collective moan when the soldiers realised that the previous day's slaughter was about to be repeated. What seemed like hope had only been deceit.

Centurions and junior officers seized the initiative, ordering retreat down the slope. With Crassus gone, there would be no clear orders from the trumpeters. Men shuffled desperately to the flat ground, peering over their shoulders. A ragged line, three ranks deep, assembled in close formation at the bottom of the dune. Shields were raised against the storm of deadly missiles that would soon be hissing down.

Crassus' once proud army huddled together, preparing to die under the burning Mesopotamian sun. Few legionaries had any will to fight remaining.

The one-sided battle did not last long. Countless Parthian arrows filled the air, punching through scuta, decimating those beneath. With no means of retaliation, all the soldiers could do was to be killed where they stood. Any who broke and ran were soon butchered. Soon Roman casualties sprawled on the hot sand in their hundreds.

By the time cataphracts were sent in for the first time, the end was nigh. The heavy cavalry pounded down the slope, ploughing into the Roman centre. Lances ripped into men's chests, horses trampled bodies into the ground, swords hacked deep into flesh. A massive gap remained where their unstoppable momentum had carried the Parthians through.

The legionaries could not take much more before they were utterly routed.

The one surviving legate ordered his legion's eagle dipped to show the desire to surrender. Romulus would never forget the symbol of Roman military might being lowered to the sand. Since he had first seen them in Brundisium, proudly borne aloft by the standard-bearers, the silver birds had stirred Romulus' blood. As a slave and then a gladiator, he had never encountered anything to really inspire him. His worship of Jupiter was like that of everyone else – hope and belief in the intangible. But the eagles were solid metal, and hard evidence of the Republic's military might: something for him to have faith in. After all, he was a Roman. His mother was Italian and so was the bastard who had raped her. Why should he not follow the eagle into battle as the regular legionaries did?

He saw many break down in tears at the shame of the defeat. Some officers attacked the Parthians blindly, preferring to die fighting than live with the ignominy, but most soldiers surrendered with relief. The desert warriors surrounded the beaten Romans, their sweating horses pressing in close. The survivors were herded together like sheep while dark brown eyes stared from behind fully drawn bows. None dared resist any longer. These were arrows that had defeated an army of thirty-five thousand men.

All unit standards, potent symbols of power, were seized and the Parthians forced everyone to throw down their swords. Those not swift enough to obey were killed on the spot. Brennus dropped his longsword with reluctance, but the Etruscan seemed less concerned about his battleaxe and Romulus soon knew why. Groups of archers dismounted and began to pick up the weapons, tying them together in bundles. Camels were being loaded with the gladii and remaining pila. The weapons were going with the captives, evidence that their fate had already been decided. Tarquinius expected to retrieve his axe later. It gave Romulus hope.

But nearly half the force involved in the final battle had been killed. The remainder – approximately ten thousand legionaries and mercenaries – were now prisoners. Defeated and dejected, the soldiers were left with nothing but their clothes and armour. Once disarmed, it was simple for the Parthians to tie ropes round each man's neck.

In long lines of human misery, they were marched south towards Seleucia. As he trudged away, Romulus did not look back at the carnage.

Behind him, hundreds of vultures were starting to land.

Chapter XXVII: Crassus

Seleucia, capital of the Parthian Empire, summer 53 BC

Life in the circular stockade where Romulus and hundreds of soldiers were incarcerated had become almost routine. Positioned near a great brick archway leading into the city, the prison of thick logs was twice Brennus' height. The men sat miserably on hard dirt inside, packed so tightly they were barely able to stretch out their legs. Rumour had it that the other captives were being held in many similar locations around Seleucia. Even unarmed, the Parthians did not trust the Romans in very large groups.

Replaced by new suffering, Carrhae and the terrible march south had already become a distant memory. Freezing nights followed the searing hot days, increasing the hardship for wounded and whole alike. There was no shelter in the compound. The Roman soldiers shivered together in the dark and burned in the sun. All known officers had been taken elsewhere, leaving only a few low-rankers to rally spirits.

Tarquinius seemed content to wait, making few comments about wind or weather. No one else knew what their fate would be. They had been spared so far, but it still seemed likely the Parthians would execute them all. Thousands of comrades had been left to rot in the desert, a shame each man felt keenly. It was Roman custom to inter the dead with pomp and ceremony. Normally only criminals were left in the open and Romulus could vividly recall the putrid smell from corpses littering the pits on the eastern slopes of the Esquiline. Only the gods knew what Carrhae would have been like.