The optio grunted in approval. The two ragged wanderers did not just possess good weapons, they also knew their way around military equipment.

'This is more like it,' said Romulus, lifting his elongated oval shield by its horizontal grip. Not since the Forgotten Legion's last battle four years before had they both been fully equipped. He scowled. It was still hard not to feel guilty about Brennus, who had died so that he and Tarquinius might escape.

'Seen combat before?' demanded the legionary.

Before Romulus could reply, a shield boss hit him in the back.

'Forward!' shouted the optio, who had shoved in behind them. 'The line in front is weakening.'

Pushing against the rows in front, they shuffled towards the enemy. Dozens of gladii, the Roman short stabbing swords, were raised in preparation. Shields were lifted until the only part of men's faces that could be seen was their flickering eyes under their helmet rims. They moved shoulder to shoulder, each protected by his comrades. Tarquinius was to Romulus' right and the talkative legionary was on his left. Both were responsible for his safety as he was for theirs. It was one of the beauties of the shield wall. Although Romulus was furious with Tarquinius, he did not think that the haruspex would fail in this duty.

He had not appreciated how thin their ranks had become. Suddenly the soldier in front slumped to his knees, and a screaming enemy warrior jumped into the gap, taking Romulus by surprise. Wearing a blunt-peaked Phrygian helmet and a rough-spun tunic, he was not wearing any armour. An oval spined shield and a rhomphaia, a strange sword with a long, curved blade, were his only weapons. This was a Thracian peltast, Romulus thought, shocked twice over.

Without thinking, he jumped forward, smashing his scutum boss at the other's face. The move failed as the Thracian met the attack with his own shield. They traded blows for a few moments, each trying to gain an advantage. There was none to be had and Romulus fast developed a healthy respect for his enemy's angled sword. Thanks to its shape, it could hook over the top of his scutum and round the sides to cause serious injury. In the space of a dozen heartbeats, he nearly lost an eye and then barely avoided a nasty injury to his left biceps.

In return, Romulus had sliced a shallow cut across the Thracian's sword arm. He grimaced with satisfaction. While the gash did not disable, it reduced the other's ability to fight. Blood oozed from the wound, running down on to the peltast's sword hilt. The man spat a curse as they cut and thrust at one another repeatedly, neither able to get past his opponent's shield. Soon Romulus saw that the Thracian could not lift his weapon without wincing. It was a little window of opportunity, and one he was not about to let slip.

Shoving his left leg and his scutum forward, Romulus swung his gladius over in a powerful, arcing blow that threatened to decapitate. The peltast had to meet it, or lose the right side of his face. Sending up a clash of sparks, the two iron blades met. Romulus' swept the other's down, towards the ground. A groan escaped the Thracian's lips and Romulus knew he had him. It was time to finish it, while his enemy's pain was all-consuming. Using his forward momentum, Romulus lunged forward, putting all his body weight behind the shield.

His power was too much for the peltast, who lost his footing and tumbled backwards, losing his shield in the fall. In an instant Romulus was crouched over him, his right arm drawn back and ready. They exchanged the briefest of looks, similar to that which an executioner gives his intended victim; there is no response other than the widening of pupils. A quick downward thrust of Romulus' gladius and the Thracian was dead.

Jerking upright, Romulus lifted his scutum just in time. His enemy had already been replaced by an unshaven, long-haired man in Roman military dress. Another one of Gabinius' men.

'Traitor,' hissed Romulus. 'Fighting your own kind now?'

'I'm fighting for my homeland,' growled the enemy soldier. His Latin proved Romulus' theory. 'What the fuck are you doing here?'

Stung, he had no answer.

'Following Caesar,' snarled the talkative legionary. 'The best general in the world.'

This was met with a sneer, and Romulus took his chance. He stabbed forward, thrusting his sword over the top of his distracted foe's mail shirt and deep into his neck. With a scream, the man dropped from sight, allowing Romulus to see the enemy lines briefly. He wished he hadn't. There were Egyptian soldiers as far as the eye could see and they were all moving determinedly forward.

'How many cohorts have we here?' asked Romulus. 'Four?'

'Yes.' The legionary closed up with him again. Thanks to their heavy casualties, they were now part of the front rank. With Tarquinius and the others, they prepared to meet the next onslaught, a combined wave of legionaries and lightly armed Nubians. 'They're all under strength, though.'

Their new enemies were clad only in loincloths; many wore a single long feather in their hair. The black-skinned warriors carried large oval hide shields and broad-bladed spears. Some, the more wealthy among them, wore decorated headbands and gold arm rings. These individuals also wore short swords tucked into their fabric belts and carried longbows. Quivers poked over each man's left shoulder. Knowing the limited range of the Roman javelin, they stopped fifty paces away and calmly fitted arrows to their strings. Their comrades waited patiently.

Romulus was relieved to see that the Nubians weren't using compound weapons, as the Parthians did. The shafts from those could penetrate a scutum with ease. It wasn't much consolation. 'How weak are we, exactly?' he demanded.

'With the fifth cohort that's guarding our triremes, we number about fifteen hundred.' The legionary saw Romulus' surprise. 'What do you expect?' he snarled. 'Many of us have been campaigning for seven years. Gaul, Britannia, Gaul again.'

Romulus looked at Tarquinius grimly. These men were hardbitten veterans, but they were badly outnumbered. All he got was an apologetic shrug. He ground his teeth. They were only here because Tarquinius had ignored his advice, insistent on checking out the dock and the library. Still, he had seen Fabiola. If he died in this skirmish, it would be in the knowledge that his sister was alive and well.

The first volley of Nubian arrows shot up into the air, hissing down in a graceful, deadly shower.

'Shields up!' shouted the officers.

An instant later, the stream of enemy missiles struck their raised scuta with familiar thumping sounds. To Romulus' relief, almost none had the power to drive through, so few men were hit. His pulse increased, though, as he noticed some of the stone and iron arrowheads were smeared with a thick, dark paste. Poison! The last time he had seen that was when fighting the Scythians in Margiana. Even a tiny scratch from one of their barbed tips caused a man to die in screaming agony. Romulus felt even more glad of the scutum in his fist.

Another volley followed before the Nubians began trotting towards Caesar's lines. Unencumbered by heavy equipment such as the rogue legionaries were carrying, they quickly picked up pace. Screaming ferocious battle cries, the enemy warriors soon reached a sprint. They were followed by Gabinius' former soldiers, who would deliver the hammer blow. Romulus gritted his teeth and wished that Brennus were still with them. The enemy formation was at least ten ranks deep, while Caesar's lines now were barely half that.

Right on cue, the trumpets blew a short series of blasts. From the rear came the shouted order, 'Retreat to the ships!' The voice was calm and measured, quite at odds with the urgency of the situation.

'That's Caesar,' explained the legionary with a proud grin. 'Never panics.'