He and Brennus exchanged a significant look. It said many things to both. Love. Respect. Honour. Pride. But there was no time to vocalise any of them.

Sensing victory, the Indians facing the First Cohort redoubled their attack. Soon half a dozen more men had died beneath Romulus’ and Brennus’ blades. Then it was ten, but the enemy no longer quailed at the danger. The scent of victory was in their nostrils. Screaming incoherently, they pushed forward, uncaring that a certain death awaited those at the front.

As Romulus’ gladius pulled free from the chest of a thin man with prominent ribs, the din of battle suddenly dimmed. From behind him came a voice.

‘Time to go.’

With Romulus’ dying enemy falling in slow motion, there was a moment of safety before another replaced him. He turned his head.

The haruspex was two steps to his rear, his battleaxe gripped in both hands. Amazingly, there was a new energy about him. Gone was the stoop, the age-old weariness. Instead the figure looked more like the Tarquinius of old.

Romulus was stunned. He felt joy and confusion in equal measure at Tarquinius’ reappearance. ‘Leave our comrades?’ he faltered.

‘We cannot run.’ Brennus glanced angrily over his shoulder. ‘You said I would face a battle that no one else could fight. This must be it.’

The haruspex regarded him steadily. ‘It is not over yet,’ he said.

The Gaul stared at him, then nodded once.

Romulus’ face twisted with anguish. He could not bear it: his hunch was correct.

Before Romulus could utter a word, Tarquinius spoke again. ‘We must leave at once, or our chance will be lost. There is safety on the far bank of the river.’

Their gaze followed his outstretched arm to the other side, which was completely deserted. To reach it, they would have to fight their way through the bitter hand-to-hand struggle between the elephants and the doomed legionaries of the left flank.

‘If we stay?’ Romulus asked.

‘Certain death. You must each choose,’ the haruspex replied, his dark eyes inscrutable. ‘But the road to Rome lies over there. I saw it in the Mithraeum.’

Mithras has kept faith with me! Grief and joy were tearing Romulus in two. He wanted to return home, but not at this price.

Brennus gave him a huge shove. ‘We’re going, and that’s final.’

Almost of their own accord, Romulus’ feet began to move. He felt numb.

With great difficulty, they managed to turn and shove their way through the packed ranks, ignoring the objections that followed. Romulus found it hardest to meet the legionaries’ angry stares.

‘Where are you going?’ demanded one.

‘Cowards!’ cried another.

‘Typical fucking slaves,’ added the man to his right.

Romulus flushed with shame at the familiar insult.

More rained down before the most vocal soldier’s voice came to an abrupt, choking halt.

Brennus’ right hand had taken an iron grip on his throat. ‘The haruspex here has told us we must follow our destiny to the left flank,’ he snarled. ‘Like to join us?’

The legionary shook his head dumbly.

Satisfied, Brennus released him.

No one else dared to speak, and the trio ducked their heads, pushing on. When they reached the edge of the First Cohort, it suddenly became easier to move. The narrow gap between it and the next unit which allowed manoeuvring in battle was still present. Tarquinius darted down it, away from the front line. The two friends followed. In less than a hundred paces, they were clear.

Behind the cohorts was a small open area. It was here that the ballistae stood.

And it was also where Pacorus, Vahram and the last of the reserves were gathered.

Romulus threw a hate-filled glance at the primus pilus, whose eyes somehow locked with his.

Barely taking time to notify Pacorus, Vahram whipped his horse into a gallop. ‘After them!’ he screamed at the nearest warriors. ‘A talent to the man who brings me any of their heads.’

The amount of gold mentioned was worth more than a lifetime’s pay for the average soldier. Every Parthian who heard responded, charging wildly in pursuit.

Thankfully, within twenty steps they had been subsumed into the heaving confusion of men and beasts that was the left flank. The cries of injured soldiers and shouted orders from the officers mixed with loud trumpeting and the metallic clash of arms. The only discernible detail was that the Roman lines were being inexorably, inevitably, driven backwards. Throwing in the reserve cohorts had failed, and shields and swords could only withstand the weight of angry elephants for so long. Craning his head, Romulus saw that the nearest behemoths were almost within javelin range. If they did not hurry, they too would meet the same fate as the legionaries at the front. Judging by the screams, it was not a pleasant way to die.

On they went, occasionally having to use the flat edges of their weapons to create a space. Romulus no longer felt dishonour at this. Theirs was a primeval struggle for survival, and since Optatus’ discovery of their status, none of these men had done anything but show hatred towards them. The last comments by the soldiers of his own cohort said it all. Romulus’ comradeship with the Forgotten Legion was dead. And Tarquinius had seen a possible road to Rome for him. It was time to take what the gods had offered.

They emerged near the river soon afterwards. A narrow band of ground was clear of combatants; the risk of falling in and drowning kept both sides away.

Romulus’ spirits began to lift. They were all three still alive and unscathed. His chest heaving, he peered at the muddy, roiling water. It flowed swiftly by, impervious to the noise and to the blood being shed only a few steps away. It was a long way to the far side. Branches and other debris swept past, revealing the river’s massive power. Crossing it would be no easy task, especially in heavy armour. He cast his eyes up and down the shore, hoping against hope that he might see a boat.

There were none.

‘Nothing for it but to swim,’ grinned Tarquinius. ‘Can you manage it?’

Romulus and Brennus looked at each other grimly; then they nodded.

Instantly the pair began stripping off their mail shirts. Whatever chance they had would be greatly increased by their removal.

Tarquinius knelt down, shoving his map and other precious items into a pig’s bladder. It had served him well on their arrival in Asia Minor two years before.

Unseen, Vahram waited until Romulus and Brennus were both in just their tunics. Driven by his hatred, the primus pilus and his horse had also emerged unharmed from the fray. Still armed with his recurved bow, Vahram calmly drew a shaft from the case on his hip and fitted it to the string. Spooked by the sudden blare of a wounded elephant, his mount jumped as he released.

The move deflected his arrow a tiny fraction.

Romulus heard Brennus gasp as if shocked. In slow motion, he turned to see a barbed metal head protruding from the muscle of his huge friend’s upper left arm. Although it was not the mortal wound that Vahram desired, swimming the river might now be too much for the Gaul. Romulus knew immediately who was responsible. Spinning around, he took in the primus pilus in a blink. Dropping his chain mail, Romulus snatched up his gladius and charged forward. ‘You bastard!’ he screamed in rage.

Vahram panicked and loosed too soon.

His next arrow flashed past, burying itself in the ground.

And then Romulus was on him. Memories of Felix’ anguished face flashed across his vision, lending him superhuman strength. Focusing his anger, Romulus reached up and took hold of Vahram’s right hand, which was frantically reaching for another shaft. With a powerful downward slice, he lopped it off.

The primus pilus screamed in agony and blood gushed from the stump, covering Romulus in a mist of red droplets. With true battle frenzy consuming him for the first time in his life, he did not care. Just one thing was important: killing Vahram. But before he could complete the task, the Parthian’s terrified horse skittered away on dancing hooves. Spinning in a tight circle, it trotted back towards the battle.