Romulus grinned and accepted the grip. 'Let's go.' Shoving through the ebbing and flowing ranks of legionaries, they soon reached the edge of the cohort. Injured men were everywhere here, screaming at the iron-tipped javelins which had struck them in their arms or legs. Those who had been hit in the neck or face sprawled uncaring on the ground, forcing Romulus and his two comrades to step over them. Mentally, he asked their forgiveness. It helped – a little.

Once in the outermost rank, Romulus took in the situation at a glance. There was no sign of an optio or centurion here, which meant that they'd been killed. The Numidian attacks had already left huge gaps in the side of the cohort. It would not be long before the beleaguered legionaries were either overwhelmed or ran away. Time was of the essence, but they also had to wait until Petreius returned from the left flank.

Ducking down behind their scuta, the trio weathered a number of Numidian attacks. There was no chance of defending themselves, just the ignominy of hiding away from the enemy javelins. Eventually, though, Romulus saw the distinctive white stallion reappear behind the regrouping cavalry. 'There he is,' he muttered, pointing.

'It's about three hundred paces,' muttered Sabinus.

'A long way,' added Paullus.

A strange calm fell over Romulus. 'Leave your shields. Helmets too,' he ordered. Wiping his bloody blade on the bottom of his tunic, he sheathed it. 'Take off your mail shirts.'

The other two stared at him as though he were raving mad.

'We stand out a mile in our gear,' Romulus hissed. 'It's also damn heavy. Without it, the Numidians might think we're riders whose mounts have been killed.'

Understanding blossomed on their faces and they began to obey. The dazed soldiers nearby looked on uncomprehendingly as the three stripped themselves of all their equipment. Underneath their thigh-length chain mail, their padded russet jerkins were saturated in sweat.

'Gods, that feels good,' said Paullus with a grin.

A shower of enemy javelins came scudding overhead and the smile disappeared from his face.

Swiftly they lifted their shields again until the attack had ended. Reaching out carefully, each man picked some Numidian light throwing spears from the dozens which lay scattered amidst the bodies.

Romulus waited until the enemy horsemen had turned around. 'Now!' he hissed. 'After them!'

The trio shot forward like Greek sprinters at a games. The retreating tribesmen did not look back and, as Romulus had hoped, their mounts concealed the trio from the Numidians who were waiting to move forward. The crucial moment would be when the two lines met, and the new wave of attackers rode out.

They had covered about half the distance when Romulus saw horses' heads appearing in the gaps between the retreating cavalry. 'Down on your bellies!' he shouted.

Sabinus and Paullus understood now.

All three threw themselves headlong to the hard ground. Pressing their faces into the dirt, they lay like dead men. Soon they could feel the earth shaking from the cavalry's approach. Romulus' heart was hammering in his chest, and he had to stop himself from trying to see what was going on.

An instant later, dozens of Numidians rode past at the canter. Shouting to each other in their own tongue, they didn't even look at the soldiers: just three more bodies on a littered battlefield.

Sabinus made to get up, but Romulus grabbed his arm. 'Stay put,' he whispered. 'The others will see us. We wait until the first lot pull back, and then do the same again.'

Fear mixed with determination in Sabinus' face. 'What then?'

'Get in between their horses,' said Romulus with as much confidence as he could muster. 'Make a beeline for Petreius.'

'And pray,' muttered Paullus from his other side.

'If we're successful?' asked Sabinus.

'Head for our lines,' Romulus replied. What chance will we have? he wondered. Little to none. The reality of their plight sank in. They'd committed themselves, though, and their comrades were depending on them.

The end of the Numidian attack was marked by a chorus of screams from the legionaries who'd been injured. Soon after that, the pounding of hooves shook the ground again as the light cavalry pulled back. Romulus waited until the last of the riders had gone past. 'Now,' he cried. 'Run as if your life depended on it.'

Jumping up, they tore after the Numidian horsemen. This time, they were closer behind the enemy, and once again none of the stationary riders saw them. Romulus counted his steps as he ran. Thirty paces, then forty. Fifty. Sixty. Still no one cried out or threw a javelin. Craning his head this way and that, he looked frantically for Petreius' scarlet cloak amid the press.

'There,' shouted Paullus, pointing to their right.

Romulus stared into the confusion of horses and riders, seeing nothing. Then his vision cleared, and he recognised the Roman general about a hundred paces away. Petreius was surrounded by a group of officers and, like Caesar on the opposite side, he was pointing and gesticulating at his enemy's lines. A dozen guards on horseback ringed him, their spears at the ready.

Mithras help me now, Romulus prayed. I do this for all my comrades. He glanced at the other two. 'Ready?'

They each gave him a grim nod.

'Don't say a word if you're challenged. Just keep moving.' Angling himself straight at Petreius, Romulus increased his speed. Within twenty steps, they had reached the ranks of the Numidian cavalry. It was a perfect example of chaos, thought Romulus, so unlike a Roman cohort. Fresh riders were making their way through to the front, cheering and laughing with the tribesmen who had just returned. Men were dismounting to check their horses' hooves or to urinate on the dry ground. There were shouts and cheers and water bags were being handed around. No one even gave them a second glance.

'Stop running,' Romulus hissed. 'Act like one of them.'

At once his companions slowed to walking pace. Covered in sweat and blood, and wearing tunics not dissimilar to the Numidians, the three deeply tanned legionaries could pass an idle glance. A sudden jolt of fear hit Romulus as he looked down. The gladii on their belts were a dead giveaway. His pace faltered for a moment. Keep moving, he told himself. They're not looking. We have not been seen.

He was right. No one confronted them as they worked their way through the mass of men and horses. One Numidian even nodded at Romulus, who grunted in reply and moved on before the warrior could ask him something. Soon they were nearing the back of the formation, and Petreius' group of officers and sentries. This party was a different prospect.

'We'll never make it to his side,' Romulus muttered from the side of his mouth. 'Those bastards are too alert. Are either of you good at long spear throws?'

Sabinus shook his head.

'Not me,' Paullus answered ruefully.

Romulus sucked in a nervous breath.

'It's down to you then,' said Paullus. 'We can bring down a few of his guards. Protect you while you take aim.'

Romulus counted their light throwing spears. He and Paullus had two each, while Sabinus had three. Seven in total. It wasn't enough, but would have to do. Then Romulus looked at the collection of enemy riders they were about to take on and his courage began to falter. 'Come on,' he hissed, moving into the open before fear made him freeze on the spot.

To their credit, Sabinus and Paullus were only a step behind. Fanning out on either side of Romulus, they readied their spears.

Romulus was so near Petreius that he could hear what the general was saying. Cocking back his right arm, he drew a bead on his target's chest. At this short distance, his iron-tipped shaft should penetrate the gilded breastplate that Petreius was wearing.