Petronius' voice came through a thick fog. 'Daydreaming will get you killed, lad.'

Romulus looked around. 'Huh?'

Suddenly seeing the split helmet and the blood covering Romulus' face, Petronius blanched. 'Are you all right?' he demanded.

'Not sure,' Romulus mumbled. 'My head hurts like a bastard.'

Petronius glanced at the enemy. As it sometimes did, the tide of battle had ripped apart the two sides in their part of the line. It was a heavensent moment. Both sets of combatants would use the brief opportunity to rest before throwing themselves at each other once more. 'Quick,' he muttered. 'Let's get that helmet off. It's no fucking use to you in two pieces.'

Gritting his teeth, Romulus let his friend undo the chinstrap and ease the battered metal off his head. He waited nervously as the other probed the gash with none-too-gentle fingers. It was hard not to scream with the pain, but somehow he managed.

'Just a flesh wound,' Petronius pronounced. Untying a sweat-soaked strip of cloth on his right wrist, he bound it around Romulus' head twice, tying it in place. 'That'll have to do until the surgeon can see to it.'

Wiping the blood from his eyes, Romulus laughed at the absurdity of it. There were so many thureophoroi and peltasts charging towards them now that the idea of having his injury treated was ridiculous. They were outnumbered by more than ten to one, never mind what was going on behind them. The thunder of horses' hooves was so loud that the Pontic cavalry must be making another charge into their rear. The Cappadocians were making short shrift of the unfortunate legionaries on the right flank. It would not be long before that section of the line gave way entirely. The end was in sight.

Petronius caught the meaning of his grim humour. He grinned. 'We're screwed.'

'I'd say so,' Romulus answered. 'Look, though.' He pointed.

Petronius didn't take it in for a moment. Then he saw. 'The aquila is still in our hands,' he roared proudly.

Men's heads turned, eager to take in any crumb of hope. Not far to their right, the symbol of the Twenty-Eighth was being jabbed aloft. Grabbing the standard from the dying aquilifer, an ordinary legionary was shouting encouragement to everyone not to give in. Waves of Pontic warriors were trying to reach him, keen to snatch the glory of winning a Roman eagle from their enemies. None succeeded. The soldier's comrades had sword arms bloody to the elbow from their stout defence of the standard. Thrusting and stabbing like men possessed, they cut down all who came near.

'Can't give up yet,' Romulus enjoined. 'Can we, lads?'

'Mars would never forgive us,' announced a short legionary with a nasty gash to his right arm. 'Elysium's gates only open for those who deserve it.'

'He's right,' shouted Petronius. 'What would any comrades who've gone before us say? That we gave up while the aquila was still ours?'

Romulus watched the sunlight glinting off the eagle's outstretched wings and the golden thunderbolt gripped in its talons. Memories of Brennus dying on the banks of the River Hydaspes ripped at his heart. He and Tarquinius had fled the field once before when an eagle yet flew. Never again. 'Charge!' Romulus bellowed, his skull pulsing with sharp needles of pain. 'For Rome and for victory!' Raising his scutum, he ran madly at the enemy, who were advancing once more.

Petronius was one step behind. 'Roma Victrix!' he screamed.

Their courage fanned white-hot by the pair's words, the nearby soldiers followed.

The Pontic warriors were not put off a few crazy Romans committing suicide when defeat was imminent. As anxious to close as the legionaries, they roared hoarse battle cries and increased their own speed.

Romulus focused on the only man he could make out distinctly with his blurred vision: a giant peltast carrying a bronze-fronted shield with a demon's face painted on it. The creature's slanted eyes and grinning mouth seemed to beckon him, promising a swift path to Elysium. Certainly the man bearing it looked unassailable, a monster whom he was in no state to fight. So be it, Romulus thought defiantly. There'll be no shame when I meet Brennus again. I'm going to die facing the enemy, and defending the eagle with all of my strength.

Ten steps separated him from death. Then five.

The huge peltast raised his rhomphaia in expectation.

Romulus heard a sound that had never been more welcome. It was bucinae, sounding the charge. Over and over they played the notes which all legionaries recognised.

Caesar had arrived.

The noise provided enough distraction for the enemy warriors to hesitate, wondering what the Roman reinforcements would do. The giant facing Romulus stared over at their right flank, which had been crumbling before the ferocious Cappadocian assault. His face took on a surprised look, and Romulus risked a glance himself. To his amazement, he saw the Sixth Legion leading the charge to support the collapsing section. Depleted from years of war in Gaul, and most recently the campaign in Egypt, it mustered no more than nine hundred men. Yet here they were, running at the Pontic infantry as if they were ten times that number.

They were doing it because they believed in Caesar.

Steely determination filled Romulus once more. He stared at the big peltast, trying to gauge his best option. Injured, lacking a helmet and only two-thirds the size of the other, he needed some weakness to exploit. He could see none. Bile rose in Romulus' throat as he took the last few steps, scutum raised high and gladius ready. Despite the rest of the army's arrival, death was going to take him anyway.

To Romulus' utter amazement, a fist-sized stone whistled past his ear and struck the peltast between the eyes. Splitting his skull like a ripe piece of fruit, it punched him into the ranks behind as if he were a child's doll. Grey brain matter splattered out as he went down, covering the men on either side. Their faces registered shock and horror. The rock had struck so fast that it appeared that Romulus had miraculously slain their huge comrade.

Then the rest of the volley landed. While the Twenty-Eighth had been fighting for its life, the ballistae had been readied outside the camp ramparts. Taking a great risk that some of his own men would be slain, Caesar had ordered the artillerymen to aim at the front of the enemy's densely packed lines. It was a risky tactic – which paid off in the richest style. Firing from less than two hundred paces away, the twenty-four catapults' efforts were lethal. Every stone killed or maimed a man, and many had enough velocity to spin off or ricochet onwards, wounding plenty more. Wails of dismay rose from the stunned Pontic troops.

Romulus could scarcely believe his luck. He had been convinced that his last moment was upon him, but Caesar's shock approach had swept that concern away. His energy renewed, Romulus leaped over the body of the peltast, smashing his shield boss into the face of a warrior with a hooked nose. Beneath his fingers there was an audible crunch as the cartilage broke, and the man went down, bawling. Romulus stamped on him for good measure as he stepped over to engage the next enemy.

On his left, Petronius had killed one of the big peltast's comrades and was trading blows with another. On Romulus' other side, a tall legionary with steely blue eyes was hacking with grim determination into a dazed-looking thureophoros.

His instincts urging him on, Romulus barged further into the mass of confused warriors. A few heartbeats later, the next shower of stones from the ballistae landed. This time, though, they were directed at the middle of the Pontic host. Aware that Roman reinforcements had arrived but unable to do a thing about it, the enemy soldiers were also helpless beneath the rain of death. Panic took them, and they began to look over their shoulders.