When Caesar had returned to Italy in December, he received the news of this, the host that was awaiting him in Greece. Keen to prevent further bloodshed, he made several attempts to open negotiations with Pompey. All were swiftly rebuffed. The Republicans had decided that they would settle for nothing less than their enemy’s total defeat. Caesar’s response was to carry the war to Greece without delay. Now Brutus laughed out loud, uncaring that his men looked at him strangely. Caesar had ignored all his officers’ advice and set sail from Brundisium. At the time, it seemed like utter madness: seven under-strength legions sailing at night, in the middle of winter, across a strait controlled entirely by the Pompeian navy. Like so many of Caesar’s daring tactics, though, it had worked; the next day his entire host landed unopposed on the western coast of Greece.

Caught napping by this, the wily Pompey then avoided battle for months, knowing that his supply situation was far superior to that of Caesar’s. With limitless ships to provide food and equipment to his army, he could afford to march up and down the land while his opponent could not. Boring the tactic might seem, but Pompey knew that Caesar’s men could not live on fresh air. They needed grain, and meat. It was during this lean time that Brutus really grew to respect their opponent. If the rumours were to be believed, Pompey was under constant pressure from the numerous senators and politicians he had in tow. The Optimates, Brutus thought scornfully. There isn’t a real soldier among them. Already resentful of Pompey’s position as supreme Republican commander, these hangers-on wanted a pitched battle and a quick victory.

So did Caesar, and when Pompey would not give it to him, he attempted to force the issue at Dyrrachium. Although by then his forces had been augmented by four more legions, it was a painful memory. The attempt to recreate Caesar’s victory at Alesia had seemed promising initially. More than fifteen miles of fortifications hemmed Pompey against the coast while dams were built to block the streams. A similar length of opposing defences prevented Caesar from advancing, but the combined constructions deprived the Republican army of water for its soldiers and fodder for its horses. By July, the bodies of hundreds of pack animals lay rotting in the sun, increasing the risk of disease among Pompey’s troops. If something wasn’t done, men would begin to die of cholera and dysentery. Meanwhile Caesar’s legionaries, who were short of supplies, ground up charax vegetable roots and mixed them with milk. The resultant dough was baked into loaves, and in a measured taunt of Pompey’s men, some of this bitter-tasting food was tossed into the enemy lines.

Fortunately for Pompey, it was then that two of Caesar’s Gaulish cavalry commanders defected. Discovering from them that parts of his enemy’s southern fortifications were incomplete, Pompey launched a daring attack at dawn the next day. Six legions took part in the massive assault. Uncharacteristically, Caesar refused to admit that his blockade was failing and launched a counter-attack, which failed miserably. Outnumbered and demoralised, his legionaries had fled the field en masse. Not even the presence of their legendary commander could stop the rout. One signifer was so panicked that when confronted by Caesar, he actually inverted his standard and menaced the general with its butt-end. Only the timely intervention of one of Caesar’s Germanic bodyguards – who sliced off the man’s arm – prevented him from coming to serious injury. The same could not be said of Caesar’s army, which lost a thousand legionaries and more than thirty centurions. Strangely, Pompey had soon called off his pursuit, allowing his opponent’s battered legions to escape the field. ‘The fools could have won the war that day, if they but possessed a general who knew how to win,’ Caesar had sneered. Brutus knew it was true.

A month passed. Again the two sides faced each other, but on an open plain this time. Caesar’s army had been depleted by injuries and the garrisoning of towns to nine legions, while Pompey still had eleven.

Superstitiously, Brutus prayed that Dyrrachium would not be repeated here today, at Pharsalus. That he would survive, and be reunited later with Fabiola. With seven cohorts as protection, she, Docilosa and Sextus were safe in Caesar’s camp, nearly three miles to the rear. If the battle was lost, the senior centurion in charge had orders to retreat to the south. It was best not to think of that eventuality, he reflected, hastily burying the thought. Then Brutus grinned, remembering Fabiola’s demand to march out on to the plain and watch the struggle. She was a lioness, he thought proudly. Fabiola had accompanied him everywhere since Alesia and now felt like his good-luck talisman. Discovering that she was also a devotee of Mithras had reinforced this feeling. They had prayed together for victory at dawn, before his departure. In that department, Brutus reflected, everything was going well. Almost everything. He sighed, thinking of Fabiola’s unexplained reticence towards Caesar. Still, it was rarely a problem. Plenty of other officers had used the excuse of the prolonged campaign to bring their mistresses along, diluting Fabiola into the mix.

‘Sir!’ shouted one of Brutus’ centurions. ‘It’s begun. Listen.’

Brutus sat up in the saddle, cupping his right hand to his ear. The sound started as a low thunder, but quickly intensified until the ground shook. Without doubt, it was the noise of hooves. Pompey’s cavalry was attacking, and in response Caesar’s German and Gaulish horsemen trotted forward, to the north-west. There were a thousand of the experienced warriors, with a similar number of specially trained light infantry interspersed between. Yet their task was hopeless. Against more than three times their number all they could do was slow the speed of the enemy attack: a delaying tactic. Brutus’ pulse increased, and he looked around, checking that his men were ready. They were, he saw proudly. Two thousand of Caesar’s finest troops, who would follow him wherever he led.

The clarion sound of bucinae ripped through the air all along the host. Vexilla, red flags, were also raised and lowered, repeating Caesar’s orders to ensure accuracy. Instantly the rhythmic tread of caligae upon the hard ground added to the noise. Two of the three lines in front of Brutus were advancing. Only one, the third, remained to hold their position. He grinned. Undeterred by the cavalry charge, Caesar was taking the battle to Pompey.

Brutus and his men waited, watching and listening to the battle commence. Impatient, nervous, none of them enjoyed holding back while their comrades began fighting and dying. Yet this was different. They had to stay put because their mission was all important.

The first to meet were the two forces of cavalry. Brutus could see the clash in the distance. Sunlight glittered off polished helmets and spear tips, clouds of dust rose and battle cries rang out. Brutus knew what it was like; he had done it before. Within moments of hitting the enemy, all semblance of formation would be lost. The struggle would immediately become a mass of confusing, individual fights, rider against rider, foot soldiers against horsemen. Hack, slash, bend in the saddle. Reassure the horse, wipe sweat from your eyes. Look around, check where one’s comrades are. Dodge a spear thrust. Move forward.

He turned to look west, wondering why the infantry had not yet met. Roman soldiers advanced towards each other in total silence, but there would still be an enormous crash of weapons against shields when it happened.

A legionary messenger came from Caesar’s position, to the rear of the third line. ‘Pompey hasn’t allowed his men to advance, sir,’ he panted. ‘They’re just standing there, waiting.’