God love him, he argued so ardently and so well that Arthur gave him Caledvwlch to wear, to show that Cai had the Duke's full authority in command.

The warriors formed the tortoise – a simple manoeuvre by which a barrier of interlocked shields is raised over the heads of those who must approach the wall – and advanced slowly, pushing the great tower before them. Arthur and I watched the battle from the fair vantage of a rock outcrop nearby.

Brave I am, foremost in battle, yet I cannot say I would gladly have been the first to leap through the tower door onto the wall. Cai did that, showing magnificent courage, battling with a dozen or more alone until one by one his men joined him. I do not know how he was not killed the moment his foot touched the wall.

Gwalchavad, Cador and Owain led their warbands into the tower next, followed by Maelgwn, Bors and Ceredig. Once these first gained the fortress wall, we could not keep the rest away. The other kings crowded one another for places beneath the tower, so that a long line of warriors stretched back from the fortress wall.

The first fighting took place on the wall itself, as I have said. But the battle quickly carried to the yard below, and that was dreadful. There was no room to swing a sword without hitting foe or friend alike, so the Cymbrogi worked with their spears. Had they been threshers they could not have taken a greater harvest! The barbarians thought to crush the attack by sheer weight of numbers and so threw their naked bodies against the British spears. The bodies fell one upon the other – a wall of twitching limbs – before Cai and the Cymbrogi, and the enemy were forced to crawl over the corpses of their kin to fight.

The British were swarming over the wall now, hurling spears down into the churning chaos. There were so many Angli pent up within the caer that our warriors killed with every throw.

'There is no honour in this,' I observed. 'It is a slaughter of unknowing beasts.'

'Baldulf is as stubborn as he is proud,' Arthur said. 'But it will be ended soon.'

As if to make a prophet of Arthur, the gate – which had been stopped up with rocks and rubble, suddenly collapsed outward in a white cloud of dust and the enemy stormed out. The British kings were ready. Custennin, Ennion, Ogryvan and Ceredig ran forth to engage the foe. The sound of the clash reached the rock where we sat.

'Are we going down there?' I indicated the battle spreading before us.

Arthur gave his head a sharp shake. 'There is no need. We will let Cai and the kings have this victory.' He turned his horse away. 'Come, we will await them in the valley.'

Baldulf s stubbornness cost him the battle. His pride cost him his life.

The barbarian would not surrender and, even when the battle was well lost, he refused quarter. Cador killed him -and set the Bretwalda's head on the end of his own skull-and-bone battle standard. He then set the standard over the corpses heaped before Caer Gwynnion.

Arthur received the victorious host in the dale. Cai, Cador, Bors and Gwalchavad led the long march down to the camp. Arthur set up his camp chair before the ford and, when the warriors crossed, he welcomed them as heroes and champions and gave them all gifts.

Cai and the others were well pleased, for the pickings were meagre on the hill. Not so much as a gold ear-ring or even a brass pin did they get there. Arthur made up the lack from the share of plunder he had saved for them. He then proposed a victory feast.

Ah, but our hearts were not in it. Weary of battle, our thoughts were on the homeward road. Harvest time was drawing near; the kings were anxious to return to their realms. They had been gone from their affairs long enough. The war, for this year at least, was won. It was time to go home.

So we formed ranks and traversed the long, wide dale of Twide eastward to where the ships lay at anchor on the coast. Then we set sail for the south.

Highest Heavenlies, be praised! Our return to Caer Melyn was all golden gladness and sweet joy. The people gathered at Arthur's hill fort and thronged the track from the ford to the very gates of the stronghold. They cheered and sang as we passed among them. Most of them were Meurig's folk, with a good few from surrounding cantrefs as well. But their welcome was every whit as genuine and heartfelt.

Arthur, first in generosity, feasted them and stood the celebration of our summer's victories out of his own treasury. The other kings enjoyed his largesse, but none offered to help provide so much as a pig or a goat for the feast.

If that is all their renown is worth, so be it. For myself, I would not care to risk a bard's mocking tongue for the price of a few pigs or bullocks.

After the feast the kings departed to their own realms, and we set about ordering the stores – for the tribute had already begun to flow into Caer Melyn from all who had pledged to uphold the War Leader. The news of Arthur's victories had stirred the lords of Britain to something resembling extravagance.

Though the winter proved dark and cold, and the snow deep – as deep as ever I have seen it, I think: clothing the hilltops and mountains in cloaks of purest white, and enfolding the valleys in mantles of thick fleece – we did not mind. The fire burned bright in Arthur's hall, and Myrddin sang the songs of valour and great deeds. Our hearts soared.

At mid-winter we observed a fine and holy Christ Mass. The new-made Bishop Teilo performed the mass, joined by Illtyd and other churchmen of renown in the region. Indeed, the church seemed especially eager to lavish its blessing on Arthur's golden head, for they saw in him the preservation of their sacred work from the ravages of the barbarians and their loathly idols. Indeed, the good brothers were the first to suffer the slaughter and torture of the heathen; always it was a priest's blood spilled on the ruined altar, the monk's body put to the flame.

So, the churchmen were right to bless Arthur, and eager to offer up every prayer for his continued good health and long life. In all, the Christ Mass at Caer Melyn that year gave us all a foretaste of Arthur's reign. And a more blessed and joyous realm I could not imagine, nor hope to find anywhere.

The winter proved far too short for my pleasure. Warmth crept back into the land; the sun lingered longer in the lifting sky. Rivers swelled with rain, the wind gentled, and the green land blossomed.

As soon as the trackways cleared, I rode to the hill-hidden breeding runs to oversee the year's colting. The breeders and trainers had done their work well: two hundred horses stood ready to join the ala. Arthur's warband would not have to walk to battle this year – nor, from the look of it, for many years to come.

I did not deceive myself that the war was over. Even with their Bretwalda dead, the Angli would not give up. They would simply choose a new leader and the war would begin again.

Had I possessed Myrddin's exalted Sight, I could not have foreseen who that leader would be, nor how powerful.

The ships began guarding the coastline as soon as the winter gales ceased for good. From Muir Guidan to the Wash, all along the Bernich coast the ships kept a restless watch. Alas, that was not how the enemy would strike this time. There would be no more sea raids, no more massed attacks on the open field, no more pitched battles at fords. The barbarians respected Arthur's genius that much at least. From now on we would fight a different war.

One morning just after Beltane a small retinue arrived at Caer Melyn. Dressed in their best finery, I did not at first know them: a dozen men in red-and-black checked cloaks, and bright tunics and trousers of blue and orange. Their hair was greased and braided, and their beards trimmed short. Gold and silver glinted from their arms, necks and ears. They held themselves erect, proud and haughty, men and women both astride stocky, winter-shagged ponies – a company of thirty in all, including a grey-mantled druid going before to lead them.