As the Roman lines moved backwards, men died in growing numbers, which weakened the shield wall. At last it disintegrated, and screaming Nubians battered their way in. With their distinctive red cloaks and gilded breastplates, the centurions were targeted first, and their deaths further lowered morale. Despite Caesar's best efforts, the battle would soon become a rout. Sensing this, the general retreated towards the dock. Instantly fear mushroomed throughout his cohorts. Men were knocked over and trampled as their comrades ran for the perceived safety of the triremes. Others were knocked off the quay and into the dark water, where their heavy armour carried them under in the blink of an eye.

'We're not going to make it,' shouted Tarquinius.

Romulus took a look over his shoulder. Only a few ships could be boarded at a time, and with the panicked legionaries unprepared to wait, the nearest ones were in real danger of being overloaded. 'The fools,' he said. 'They'll sink.' He refused to panic. 'What can we do?'

'Swim for it,' the haruspex replied. 'To the Pharos.'

Romulus shivered, recalling a previous time that they had escaped by water. Left behind on the bank of the River Hydaspes, Brennus had died alone. The shame of deserting his comrade had never quite gone away. Romulus forced himself to be practical. That was then, this is now, he thought. 'Coming?' he asked the legionary to his left.

There was a terse nod.

As one, they shouldered their way past the confused and terrified soldiers surrounding them. In the confusion which now dominated, it was easy enough to break out of the battered Roman formation and make for the water's edge. They had to take extreme care. Slick with blood, the large stone slabs were festooned with body parts and discarded equipment. Leaving the burning warehouses further behind, the trio were soon moving through semi-darkness. Thankfully, the area was empty. The fighting was confined to the area around the triremes and the Egyptian commanders had not thought to send men west along the dock to prevent an escape.

Their oversight did not matter, thought Romulus, staring back at the slaughter. Wild panic had now replaced Caesar's men's earlier courage. Disregarding their officers' orders, they fought and scrambled to escape. He pointed at a trireme second from the quay. 'That one is going to sink.'

Raising a hand to his eyes, the legionary swore. 'Caesar's on it!' he cried. 'Damn the filthy Egyptians to Hades.'

Romulus squinted into the light, finally seeing the general amid the throng. Despite the shouts of the trierarch – the captain – and his sailors, more and more soldiers were climbing aboard.

'Who'll lead us if he drowns?' cried their companion.

'Worry about him later. Let's survive ourselves first,' replied Romulus tersely, stripping down to his ragged military tunic. At once he buckled his belt back on, thus retaining his sheathed gladius and his pugio, the dagger which served both as a weapon and a utensil.

Tarquinius did likewise.

The legionary looked from one to the other. Then, muttering dire imprecations, he copied them. 'I'm not the best swimmer,' he revealed.

Romulus grinned. 'You can hold on to me.'

'A man should know who's going to save his skin. I'm Faventius Petronius,' he said, sticking out his right arm.

'Romulus.' They gripped forearms. 'He's Tarquinius.'

There was no time for further niceties. Romulus jumped in, feet first, the haruspex behind him. Petronius shrugged his shoulders and followed. Their distance from the battle meant the three splashes went unnoticed. At once Tarquinius beat a diagonal path out into the harbour. They needed some light to see, but had to stay far enough out to avoid the enemy missiles. With Petronius holding on for dear life, Romulus took up the rear.

How good it would be to catch Fabiola's ship, he thought. It was long gone into the night, though, no doubt headed for Italy. The same destination he had been trying to reach for the last age. Despite his own predicament, Romulus did not give up all hope. Time and again, Tarquinius had said there was a road back to Rome for him. That dream was what kept him swimming. With each stroke, Romulus imagined arriving home and being reunited with Fabiola. It would feel like reaching Elysium. After that, there was unfinished business to be done. According to Tarquinius, their mother was long dead, but she still had to be avenged. Killing the merchant Gemellus, their former owner, was the way to do that.

A flurry of splashes, accompanied by shouts and cries, dragged Romulus' attention back to the present. Scores of legionaries were jumping off the outermost trireme, which was foundering under the weight of too many men. Their fate in the water was no better than on board. Most were immediately dragged under by their armour, while those who could swim were targeted by enemy slingers and archers already positioned on the Heptastadion.

Romulus winced at their plight, but there was little he could do.

Petronius' gaze was also fixed on the unfolding drama. A moment later, his grip tightened.

'Easy,' Romulus snapped. 'Trying to choke me?'

'Sorry,' Petronius replied, relaxing his hold. 'Look though! Caesar's about to jump ship.'

Romulus turned his head. Lit from behind by the blaze from along the eastern harbour, he could make out the agile figure which had rallied the legionaries earlier. No longer was he attempting to control his men. Caesar had to flee now too. Off came his transverse-crested helmet and red cloak, and then his gilded breastplate. Surrounded by a group of legionaries, Caesar waited until all were ready. Then, clutching a handful of parchments, he stepped off the side rail and into the sea. His men landed around him, sending fountains of water into the air. With a protective cordon established, Caesar began swimming towards the Pharos, keeping one hand upraised to keep his paperwork dry.

'Mithras, he's got balls,' Romulus commented.

Petronius chuckled. 'Caesar is scared of nothing.'

A flurry of arrows and stones splashed down nearby, reminding them that this was no place to linger. While the majority of the Egyptian soldiers continued to assail the cohorts stuck on the dock, others were hurrying on to the Heptastadion. From there they could send unanswered volleys at the helpless legionaries in the water.

Romulus was horrified by the slingers' accuracy. The light cast on to the calm surface of the harbour was not that bright. Lower than the docks, and obscured to some extent by the Heptastadion, he had thought their journey would be reasonably safe. Not so. Fitting stones half the size of a hen's egg into their weapons, the slingers whirled them around their head once or twice before letting fly. Perhaps two or three heartbeats went by before another shower was released. A third and a fourth followed in quick succession. Soon the air was filled with the missiles; jets and spouts of water rose up as they landed. Again and again, Romulus saw legionaries being struck on the head. He cringed at the final-sounding impacts. Either they killed on the spot or knocked the victims unconscious, whereupon they drowned. That was if an arrow didn't take them through the cheek or in the eye.

Soon the enemy slingers and archers needed more targets. Because of their decision to swim further out, Caesar's group was still unscathed, like themselves. The status quo would not last, though. Thanks to the lack of Caesarean troops on the Heptastadion, the Egyptians could pursue them on a parallel course, raining death down with impunity.

'Faster,' urged Tarquinius.

Splash, splash, splash. A torrent of missiles and rocks hit the water not twenty paces away, increasing Romulus' pulse. Petronius' breath grew ragged on his neck. They had been seen. He increased the speed of his strokes, trying not to look sideways.