From outside came the clash of arms and Darius’ voice, bellowing orders. The Scythians had attacked.

‘Your comrades need you,’ said Aesius.

Romulus knelt and took hold of Aesius’ bloody forearm in the warrior’s greeting. The weak optio could barely return the grip, but Romulus saw that the gesture meant a lot. ‘Go well,’ he whispered.

He moved behind Aesius, who lowered his chin on to his chest. This exposed the nape of his neck. Holding the hilt of his gladius with both hands, Romulus lifted it high in the air, its sharp tip pointing down. Without pausing, he stabbed into Aesius’ spinal cord, cutting it in two. Death was instantaneous, and the optio’s disfigured body slumped silently to the floor.

He was at peace.

His heart heavy, Romulus studied the prone form at his feet. But anger gradually replaced the sorrow. Forty good men had been maimed for no good reason. And outside, more were dying. Bloody sword in hand, he turned and ran from the building. The others had already disappeared, so Romulus sprinted towards the gate. The clash of arms mingled with men’s screams, the noise of horses’ hooves and shouted orders from Darius. Battle had been joined. Wishing that Tarquinius were there too, Romulus emerged from the fortlet to a scene of complete mayhem.

In partial testudo formation, the two centuries were holding firm.

Beyond them galloped large groups of Scythian warriors, loosing arrows at the legionaries as they rode to and fro. It reminded Romulus of Carrhae. But the bearded, tattooed horsemen were dressed differently to the Parthians, with marmot fur or wool cloaks, dark woollen trousers and knee-high felt boots. Few of the dark-skinned horse archers wore armour, yet they were armed to the teeth, carrying short-headed axes, swords and knives as well as their bows. Their mounts were a magnificent deep red colour, and their blue saddles were richly decorated with gold thread. These were wealthier men than the riders who had devastated Crassus’ army.

Romulus glanced at his comrades. Thankfully, the silk coverings on their shields were safely stopping the Scythian arrows. Already their surfaces were peppered with them. But there were a few casualties. Four men had received wounds to their lower legs. Another must have been looking up when the first volley was released. Lying to the unprotected rear with the others, he twitched spasmodically. One hand still clutched the wooden shaft protruding from his throat.

One dead, four injured, thought Romulus grimly. And the fight had barely begun.

Loud screams drew his attention once more. Almost as one, the four legionaries had begun thrashing about, their faces contorted in pain. Their reaction was extreme, confusing Romulus. They all had routine flesh wounds. Then he remembered. Scythicon.

Tarquinius had told him how the poison was made. Adders were captured and killed, and left to decompose. Next, sealed vessels of human blood were allowed to putrefy in animal dung. The final mixture of rotting snake, blood and faeces formed a toxic liquid that killed within hours of wounding a man. It meant that every Scythian arrow provided a guarantee of death. How could Pacorus be any different?

But that was the least of his worries right now. A finger of fear tugged at Romulus’ heart. He did not want to die screaming in agony. And the same emotion was evident in the faces of the legionaries in the rear ranks. The cries of the wounded were doing little for morale.

There were at least a hundred figures on horseback pinning them against the fortlet’s wall. Pleasingly, about two score more lay sprawled in the dirt, taken down by the first shower of Roman javelins. Wary of using their last missiles, Darius had not yet ordered another volley. His last bodyguard was using his bow to deadly effect, however. Taking his time, the Parthian was loosing well-aimed arrows, invariably killing a Scythian with each shot. But his efforts would soon come to a halt. The case-like quiver on his left hip only held twenty to thirty shafts.

‘Into line, soldier!’ shouted one of the optiones at Romulus.

Spotting Brennus’ huge frame at the front, he shoved his way through to join him. Even on his knees, the Gaul towered over the others. Lowering his scutum to meet the others in the shield wall, Romulus knelt down on the cold ground beside his friend. The men in the second rank held their scuta angled overhead to protect those in front while those behind covered their own heads. The testudo was an extremely effective defensive formation. Romulus’ misery lifted a fraction. They could hold their own against these attackers.

‘Stand fast! Protect yourselves from their arrows,’ shouted Darius, his perspiring face determined. ‘Let the bastards use them all up. We’ll stay inside the fort, and in the morning we can march out of here.’

At this, there was a loud cheer. Not everyone would fall to the poisoned shafts.

Romulus turned to Brennus. ‘Can’t be that simple,’ he muttered. ‘Can it?’

‘I doubt it,’ replied the Gaul with a scowl.

‘There aren’t enough warriors to wipe us out.’

But there were no more visible, and clearly Darius thought that the riders pounding back and forth in front of them were their only attackers.

The nomads must have heard of the silk protection on their shields, thought Romulus. Word had spread fast through the border region about the Forgotten Legion’s secret weapon, meaning that most tribes were wary of attacking unless in great force. No leader could think that a hundred horse archers would be able to stop two centuries marching out to freedom. Slow them down, yes. Annihilate them, no. And if Darius’ messengers safely delivered their message, reinforcements would arrive by the next afternoon. What was going on?

Romulus peered over the iron rim of his shield, his eyes flicking from left to right. There was a small group of Scythians at the enemy’s rear, directing operations, but no sign of any more warriors. Mithras, help me! He took a deep, uncertain breath as his gaze was drawn upwards, over the milling horsemen. Clear blue sky. On the horizon, a few clouds. A faint breeze coming from the north. Attracted by the fighting, vultures were already beginning to circle high above. Romulus considered what he saw for a long time. Dread filled his heart, but eventually he was sure.

‘We need to fight our way out,’ he muttered. ‘Now.’

The big Gaul was surprised. ‘Why? It’s nearly nightfall. Better to do what Darius says.’

Romulus put his lips to Brennus’ ear. ‘The omens are bad.’

Brennus looked confused. This was normally Tarquinius’ territory. ‘You’re sure?’ he asked.

‘Yes. I asked Mithras for help and he gave it,’ whispered Romulus vehemently. ‘These are the scouts for a much larger force that will arrive at dawn tomorrow.’

‘They’re just keeping us here?’

‘Precisely,’ finished Romulus.

Used to Tarquinius’ accurate predictions, Brennus let out a heavy sigh. He scanned Romulus’ features again, searching for proof.

‘I don’t understand either,’ hissed Romulus. ‘But I saw a vision of Rome earlier too.’

The Gaul spat a curse. ‘Very well. Speak to Darius. Tell him what you saw.’

By now, the Scythians had stopped wasting arrows by firing at the silk-covered shields. Instead they were letting them fly in curving arcs that came down to the rear of the testudo. Pushing his way out, Romulus was greeted by the sight of the injured soldiers transfixed to the ground. The unfortunate men who had been treating them had also been hit. Now they would die too. Still uninjured, Darius was standing nearby, with his guard holding a discarded scutum over both their heads. Both their horses had been struck by arrows and were charging wildly around the inside of the fortlet. Not for long, thought Romulus grimly. The scythicon would already be pumping through their veins.