Prefect Herophilus nodded a greeting as his commander rode up.

'Your men will be in action soon.' Cato pointed to the dark line of riders approaching, the rumble of their hoofs clearly audible above the ongoing cacophony of Nubian instruments. 'Are they ready to do their duty?'

It was a rhetorical question, but it gave the prefect the chance to speak up for his men.

'My boys will be as steady as a rock, sir. You can depend on us.'

'I know it. If you don't mind, I will join your command for the present, and see for myself how your men fight.'

Herophilus bowed his head. 'My pleasure, sir.'

Both officers turned to watch the enemy. Cato struggled to make sense of their numbers due to the dust that engulfed those a short distance behind the leading ranks.

'There must be thousands of them,' said one of Herophilus's decurions.

'Quiet there!' the prefect snapped at him.

The enemy closed to within half a mile and Cato heard the clack-clack-clack of the bolt throwers as the crews prepared to shoot up the Nubian cavalry. Some of the auxiliary horsemen, distracted by the spectacle of the enemy force, allowed their mounts to move out of position until Herophilus cupped a hand to his mouth and bellowed, 'Keep the bloody line there! Decurions! Take the name of any man who can't control his horse!'

The sound of drumming hoofs filled the air and now Cato could feel the vibration through the ground beneath his mount. To his right he heard the officer in charge of the archers order his men to make ready. Then there was a brief stillness over the left flank of the Roman army as they stood their ground and waited for the action to begin. In that moment the sun finally crested the hills to the east and its rays poured over the battlefield, bathing polished armour and weapons in a fiery glitter.

The warm glow was suddenly pierced by the shadowy dashes of the missiles as they were unleashed from the bolt throwers and an instant later the crack of the torsion arms carried to Cato's ears. He watched the fall of shot and saw a rider plucked off his horse and hurled to the ground. More riders went down, together with horses, but they were quickly swallowed up by the waves of Nubian cavalry surging forward. More bolts slammed into the charging mass, and then the archers added their weight to the bombardment, their arrows angling higher into the sky before plunging down. Scores of Nubians were struck down, and yet it seemed to make little difference to their numbers or break the pace of their charge.

Cato drew his sword and his officers followed suit. Herophilus slipped his left arm through the straps of his shield and took up the reins as he shouted orders to his men, his voice shrill with the strain of being heard above the deafening pounding of hoofs. 'Close up! Shields to the front! Make ready your spears and prepare to receive the charge!'

There was a shimmer as the long line of spear tips swept down towards the Nubians. The auxiliary horsemen drew their shields in close, covering as much of their bodies as possible. Beneath them some horses stirred nervously until steadied by a press of the thighs or a calming word. The enemy riders had closed to within a hundred paces now and Cato could see individual details. The riders' mounts were all at full stretch. Their formation had lost cohesion due to the speed of the charge and the loss of those who had been shot down by the archers and bolt throwers. They were still shooting, keeping the range long enough to avoid any danger to their own side, while lashing down on the Nubians at the rear of the charge.

'Here they come!' Herophilus shouted, his eyes wide.

An instant later the first of the enemy reached the Roman line. Their horses shied at the line of mounted men and the deadly points of their spears, and the impact of the charge broke as the melee spread along the line. The prefect and his officers dug their heels in and forced their way amongst the men to join the fight, the cohort's standard bearer following on, keeping the standard raised high for all his comrades to see. Cato edged his mount forward, to just behind the second rank of Roman horsemen. Beyond was a savage sea of gleaming blades, thrashing limbs, the dagger-like ears of horses and wild tossing manes, all accompanied by the harsh clatter and thud of weapons and the cries of rage and pain and whinnies of terrified and stricken cavalry mounts.

'We'll not hold back that host,' said Junius. 'We can't.'

'We must,' Cato replied simply. 'Or die.'

But even as he spoke, more and more of the enemy were pressing forward, forcing the Roman line back.

'Follow me!' Cato commanded, urging his horse forward. He pressed into the melee, knee to knee with the men on either side. They glanced at him in surprise before focusing again on the enemy. Cato raised his sword and gripped the reins tightly in his left hand. He was conscious of not having a shield but it was too late for that. He was committed to the fight and must stay with the men or look a coward if he drew back. To his right he was aware of Junius struggling to stay with him, but another rider intervened and the tribune was forced away and could not safeguard Cato's side.

A gap opened up between two auxiliaries directly ahead and Cato edged his mount into the space, fixing his gaze on the nearest of the Nubians, a lean figure with an ebony face split by brilliant white as he bared his teeth. He spotted Cato and urged his horse forward, raising a heavy curved blade overhead. Cato punched his arm up to block the blow and it glanced away, thudding into the shield of the auxiliary to Cato's right. The man swung round in his saddle and, with an overhand grip, thrust his spear at the Nubian, striking him in the chest. The folds of the robes he wore, together with whatever armour he had beneath, kept the spear point out of his flesh, but the impact drove him back all the same, almost toppling him from his saddle. Cato took advantage of the moment of imbalance and slashed at his sword arm, cutting into his elbow joint. The sword hand spasmed, releasing its grip, and the heavy weapon tumbled down between the flanks of the horses and out of sight. The Nubian howled with agony as he recovered his seat and hauled on the reins, trying to turn his horse away. He succeeded in bringing the beast side on, where it was trapped between the battle lines and left the man exposed to the second spear thrust which pierced his side, under his armpit, and went in deep. A rush of blood accompanied the spear as the auxiliary yanked it free, and the Nubian swayed a moment before falling amid the dust and stamping hoofs.

Cato took the chance to glance round and saw Junius dispatch an enemy with a savage cut to the head. Elsewhere the line had stopped giving ground and the better armour of the Romans meant that they were getting the best of the individual duels. Nor was the enemy pushing forward any more. They had been fought to a halt and as Cato saw, they were giving ground. The reason for this was clear enough. Over the heads of the men in front of him, Cato could see Roman arrows plunging down into the tight press of bodies behind. The Nubians there were anxiously doing their best to shield their bodies with the small round hide shields that most of them carried, but they were poor protection against the barbed iron points. Several men and horses were hit at a time, the wounded animals rearing as the pain of their injuries made them panic and impossible to control.

'Push them back!' Cato roared, edging his mount forward, pressing up against the riderless horse and forcing it aside. A Nubian passed in front of him, out of sword reach, and Cato stabbed his mount in the rump instead. The horse let out a shrill cry and kicked back, narrowly missing Cato's leg, but striking the flank of his mount so hard that Cato heard a rib snap beneath the glossy hide. Abruptly both animals reared up, the Nubian thrown back into Cato's side as he threw his weight forward and clung on tightly to the reins to stay in his saddle. The Nubian's flailing hand caught Cato's tunic above his knee and the fingers clenched. Cato felt himself shift to the side and the terrifying prospect of falling to the ground and being trampled seized him. He cursed the man through gritted teeth and then swung his sword arm over and tried to cut at the hand. But the gap was too cramped to get a swing and the edge pressed into the flesh and did not cut through. Cato desperately started a savage sawing movement in the space that he had and the Nubian howled and a moment later was forced to release his grip and fell beneath Cato's horse where his panicked cry was brutally cut short.