Tarquinius' opinion of her was strengthened when a bleary-eyed Antonius appeared in the doorway. After challenging the doormen, he had a muffled conversation with Fabiola. Then, to Tarquinius' surprise, he let them go. The door immediately closed, preventing any further insights. Drawing the conclusion that he had been guided to the Lupanar by his dream, the haruspex grinned. The gods wanted to show him that although there was danger in Rome, Fabiola for one was well able to look after herself.

There was no need for him to watch over her so closely.

Tarquinius had no idea how wrong he was.

Several weeks go by… The north African coast, winter 47/46 BC The sea was calm now, a different creature to the monster that had battered Caesar's ships on the three-day crossing from Lilybaeum in Sicily. Under a clear blue sky, gentle waves rolled in, rocking the two dozen or so anchored triremes and flat-bottomed transports that lined the shore. Soldiers disembarked, gratefully jumping down into the shallow water before being handed their kit by their comrades. Using special timber frames, horses were lifted from the holds and then lowered into the sea. Their riders then led them ashore. Sacks of foodstuffs, spare equipment and dismantled ballistae were passed hand over hand by chains of legionaries to the ground above the waterline. Under the close supervision of a quartermaster with a tally sheet, they were piled in neat stacks.

Further inland, the playing-card shape of a camp had been marked out; Caesar's tent and the pavilion for the headquarters had been pitched first, their positions in the centre marked by a red vexillum. Hundreds of men were digging the first fossa, using the earth from their efforts to form the beginning of the defensive rampart. Centurions and optiones strode up and down, encouraging the toiling soldiers with alternating promises and threats. In a giant arc around them stood fully half the legionaries present, guarding against sudden attack by the enemy. In the midst of these was Romulus.

The scene was the picture of order, he thought proudly. The Roman army at its efficient best. He was only a small part of it, but he belonged now, which counted for so much. For the first time in his life, Romulus was somewhere that he wanted to be. He would be eternally grateful to Caesar for that. As a result, his dreams of seeing Fabiola and of killing Gemellus had been placed firmly on hold. He owed his freedom to Caesar and, in Romulus' mind, that debt had to be paid back before he could contemplate pursuing his own path again. He would repay Caesar by being a loyal and brave soldier for however long was necessary. Romulus adopted a practical approach to the effect this had on his plans. Thus far, the gods had seen fit to protect Fabiola, and with their help, she would continue to be safe. Just as they were saving Gemellus' miserable hide for him, he thought, gripping his pilum tightly. Every night, after his prayers for his sister's wellbeing, Romulus asked for the fat merchant to be alive if he ever returned to Rome.

Of course there was no guarantee that he or his comrades would survive. The campaign had got off to a bad start, with Caesar already proving fallible. Setting sail against the advice of his soothsayers and without instructing his captains where to land, Caesar and his men had run into severe weather, which had broken up the fleet. In another seemingly bad omen, the dictator had stumbled and fallen that morning as he jumped from his ship into the surf. In a master stroke, Caesar turned the ominous moment on its head by grabbing two big handfuls of shingle and shouting, 'Africa, I have hold of you!' Everyone present had been able to laugh off their superstitious reaction.

Yet their situation remained critical.

Although few men had been lost, only a fraction of the force which had set out from Lilybaeum was in this anchorage. Instead of six legions, Caesar had only 3,500 legionaries, mostly cohorts from different units. More worryingly, thought Romulus, the dictator had fewer than two hundred horsemen, while the Pompeian troops in the area were dominated by Numidian cavalry. Romulus knew all too well how dangerous that could be: Crassus had also retained insufficient horse. He trusted that Longinus, the grizzled officer who'd interrogated him on Caesar's behalf, had passed on this critical detail. Unlike Crassus, Caesar trusted and relied on his subordinates, many of whom had served him for years.

However, there was little Caesar, or anyone, could do about this glaring weakness for the moment. The rest of the army had been carried off by the strong winds and heavy seas, and only the gods knew where they were now. Ships had been dispatched to scour the coast, but their quest could take days. Days in which the enemy could well discover their position.

Romulus grimaced. That eventuality did not bear thinking about. Caesar would cope. They all would – somehow. In the meantime, it was time to dig in and pray that their reinforcements arrived soon. A week passed by without event. Most of the scattered fleet was rounded up and brought to join the small force that had disembarked with Caesar. While still severely outnumbered, his army had also been blessed with good fortune. The local Pompeian forces – more than ten legions strong – proved to be widely dispersed along the coastline. Led by Metellus Scipio, they had been caught napping by Caesar's arrival in the middle of winter. It was only a few days into the new year – hardly the time to start a campaign. Typically, that is just what Caesar had done. Now his enemies needed time to gather their strength, which afforded the dictator crucial breathing space.

The realisation that Caesar had probably expected this lag phase helped increase Romulus' admiration for his leader. The man knew that most soldiers thought in a regimented fashion, only ever fighting in daylight and waging war when it was supposed to happen – in the summer. So he did the opposite. Yet Caesar's lightning-fast tactic had brought a major problem of its own: that of providing the legions with supplies. The empty transport ships were already on their way to Sicily and Sardinia, their mission being to bring back the grain for which there had been no space on the voyage over. In the meantime, though, Caesar's main business was not seeking battle with the enemy, but rather finding food for his men. For a number of reasons, this task was proving more difficult than anticipated.

Romulus had been pondering the problem himself. Stuck on sentry duty much of the time, there was little else to do. Caesar's army could not forage far inland for fear of being cut off from the coast and the reinforcements, which were landing daily. Several veteran legions had yet to arrive, and their presence in a set-piece battle would be crucial. Like the Twenty-Eighth – Romulus' unit – most of Caesar's legions had been formed during the civil war, and were relatively inexperienced.

They still needed food, though. Lots of it.

Unfortunately, local agriculture had been disrupted in a major way. As well as gathering all the food they could find, the Pompeians had conscripted large numbers of peasants into their army. The farms in the fertile landscape were thus largely empty, forcing Caesar's men to harvest any remaining crops for themselves. Inevitably, these did not last for long, and so the dictator had led his legions to the nearby town of Hadrumentum. The Pompeian garrison there barred the gates and refused to surrender. Caesar had neither the time nor the equipment to put a siege in place, so marched on to Ruspina, where he established his main base. Leptis, another local settlement, soon opened its gates to the Caesarean forces, but neither Leptis nor its neighbour were capable of supplying thousands of soldiers for more than one or two days.