We would soon be crushed by the weight of their numbers alone.

Where was Uther?

Great Light, I prayed with every breath, if you mean to save us today, let it be now!

We fought, grimly hacking at the foe before us. Not a man among us could swing his blade without wounding an enemy. Yet we were losing ground quickly now, as more and more of the barbarians pushed across the river. One band and then another, and another, and still more succeeded in getting round our flanks. We were now almost surrounded, and were being forced into a circle: the death circle, warriors call it, for once adopted there is only one outcome of this manoeuvre.

Where was Uther?

The Saecsen horde, seeing us apparently deserted by cm-allies, screamed their blood lust to their loathsome gods, calling on Woden and Tiw and Thunor, to maim and slay and destroy. Eager to make British blood the sacrifice, they leapt slavering to the fight.

I slashed at every bit of exposed barbarian flesh that offered itself. I worked as the harvester Jabours before the lowering storm. I reaped a vast harvest, but took no pleasure in my mowing. Men fell beneath my streaming blade, or beneath my mount's brain-spattered hooves. I saw men contemplating severed limbs; I saw brave warriors weeping into their death-wounds. I saw faces, sun-bronzed and fair, with eyes the colour of winter ice, once whole and handsome, now twisted in unreasoning agony, or broken and bloody in death.

But no matter how many I slew, more crowded in. Clutching, thrusting, grappling, hewing with notched and ragged blades. One great chieftain loosed an ear-splitting scream and leaped onto the neck of my horse; he clung there with one arm, flailing at me with his war axe.

I flung myself backward in the saddle. His blood-stained blade sliced the air where my head had been and I thrust with the point of my sword, catching him just under the line of his ribs. He roared and dropped his axe, then grabbed the sword with his hands and held it as he fell, seeking to pull me from the saddle with him. My sword was dragged down by his weight and one of his comrades, crazy for the kill, lofted his axe to cleave my skull.

I saw the blade hover in the air. Then the wrist spouted blood and the axe spun awkwardly away. Pelleas, ever alert to my danger, had reached me; and it was not the first time his sword had delivered me. 'Stay with the king!' I shouted, jerking my sword free at last. Pelleas turned and darted after Aurelius, who was charging on ahead, bodies toppling behind him.

The Britons strove mightily against the foe. Never were men more courageous in going to their doom… but there was nothing we could do. Though we slew one, four more arose to take the place of the one; though we slew a thousand, five thousand more remained. Meanwhile, our brave companions were falling beneath the relentless slaughter.

We were completely surrounded now. Aurelius sounded the call to circle the troops. This is the beginning of the end for any army. Knowing this, hating it, we rallied. I do not know where the strength came from but, with prayers and curses, and broken weapons in our hands, we forced the screaming Berserkers back once more.

This angered Hengist, who committed the rest of his vast war host against us – all save his House Carles, his own personal bodyguard made up of the strongest, most formidable of all the Saecsen warriors. Aside from these, every last warrior was pressed into the fight. He intended destroying us utterly.

Across the river they came, streaming towards us, then-faces tight with the ecstasy of hatred. We were slowly being crushed by the steady advance of the enemy. The heads of our countrymen now adorned the long spears of the foemen. Smoke from burning corpses began to drift into the air. So Hengist reckoned that he had won already.

But he reckoned falsely, for the battle was not over yet.

Aurelius saw it first. 'Uther!' he cried. 'Uther has taken Hengist!'

How he saw this, busy as we both were, I cannot say. But I lifted my eyes and scanned the hillside opposite – the tide of battle had carried us back up the hill where we had begun – and I saw a force of mounted men surrounding Hengist's horsetail standard, and the fight there seemed over. The rest of Uther's force was galloping across the river to cut off the enemy rushing to their leader's aid.

I do not know when Hengist realized his mistake, but it must have struck him like a cold blade between the ribs when he turned defenceless to see Uther swooping down on him from behind.

For our part, we sensed the sudden shift in the battle, just as the enemy was about to overwhelm us. We braced for the final thrust, and then, inexplicably, fell forward as the enemy melted away.

Just like that, all at once, the weight of the battle fell from us like a wall crumbling inward upon itself after leaning outward for so long. Aurelius wasted not a moment. He wheeled his horse, snatching up the royal standard, and, waving the proud Eagle above his head, he mounted the attack.

Great Light, we are saved!

Aurelius retaliated quickly and without mercy. Instantly, the remaining horsemen gathered to him and they rode down the enemy from behind.

There is no honour in slaughtering a fleeing foe – only grim expedience. It had to be done.

Caught between the two forces, the barbarians found themselves waist-deep in the Nene, unable to advance or fall back. Confusion seized them and shook them like a dog shaking a rat. Chaos closed its fist round them and they gave in to it. Hengist was securely held; those of his bodyguard still alive, were bound, as he was, and disarmed.

It is a curious thing with the barbarian, but capture a war leader and the fight quickly goes out of them. Let him be killed and they will go on fighting for the honour of accompanying their lord into Valhalla; let their battlechief fall prisoner and they become confounded and dismayed and are easily overcome.

It is as if theirs is a single mind, a single will – that of their leader. And without him they fall instantly into panic and despair.

Therefore, despite superior numbers, despite the awful fact that our main force was well and truly beaten, once Uther held the blade to Hengist's throat, the Briton had prevailed.

The battle continued only in isolated enclaves, mostly Pict and Irish whose chieftains still lived to lead them. These were quickly put down. Would that the Saecsen had behaved that way, for now Uther was left with the odious task of dealing with the prisoners.

Of course, Aurelius had not intended that there should be any prisoners, but that the fight should have been fought to the death. Had the Saecsen won, it would have been. Though a warrior might kill in the heat of battle, slaying time and again without hesitation, among civilized men there are not many who can slaughter defenceless human creatures as they stand mute and passive before him.

I say this because, when the fighting was done, there remained several thousand Saecsen still alive and it was simply not possible to run the spear through them all. If we had, we should have been worse barbarians than those we fought!

'Well?' I asked Uther. He was still in the saddle, his bloody sword across his thigh. 'What will you do?' Aurelius had sent me ahead to Uther while he saw the smaller fights ended and organized aid for our wounded.

Uther scowled darkly, as if it were somehow my fault that this decision had fallen to him. He sought to put off the question by asking, 'What says Aurelius?'

'The High King says you are war leader; it is your decision."

He groaned. Uther was no murderer. 'What do you say, Exalted Ambrosius?'

'I agree with Aurelius. You must decide – and quickly, if you will not lose the trust and respect of your men.'

'I know that! But what am I to do? If I kill the prisoners I am a butcher, and I lose respect; let them live and I am soft-hearted, and I lose even more.'