Once inside, Evnissyen stretched out full length, pressing hands and feet against the sides of the cauldron. He pushed with all his might until the marvellous cauldron burst into four pieces and was ruined. As it happened, the wicked man's heart burst also and he died ignobly.

The survivors, all British men, came upon Bran who lay dying beside fair Bronwen. They fell on their knees and wept over him. 'Lord and king,' they wailed, 'the cauldron has burst and now we cannot save you.'

'Listen to me, my brothers,' Bran said, 'and do what I tell you. When I am dead, cut off my head and take it back with you to Ynys Prydein. There let you bury it on the White Hill overlooking Mor Hafren, where it will guard that sea gate from any intruder.

'I tell you the truth, for so long as you do not dig up the head no enemy will ever harm you. You will feast in the land of your fathers, Rhiannon's birds will sing to you, and eighty years will be as a single day. In this way, the head will be as good a companion to you as ever it was, for your joy and prosperity will be assured.

'But let anyone uncover the head and plague and war will come once more to the Island of the Mighty. And, once uncovered, you must hasten to bury it again where no one will ever think to find it, lest worse befall you.

'Now then, it is time for me to die. Do at once what I have commanded you.'

Sorrowfully, the British men did what their lord commanded. They sailed back over the sea to their homeland and buried the head where Bran had told them. And they buried Bronwen a little apart, but near the place where her brother's head rested, so that they could be together.

And, all at once, up sprang a great palace with walls and floors of polished stone that shone like gemstones in the sun. Inside they found an enormous hall and food of all kinds laid upon the groaning board. There was wine and mead and beer to drink. And whether food or drink it was the finest they had ever tasted. As they began to feast, three birds appeared on golden perches and all the most wonderful singing they had ever heard was like empty silence compared to the singing of these marvellous birds.

And the men forgot the sorrow of their lost kinsmen and companions, and remembered nothing of the grief they had seen and suffered, nor any other hardship in the world.

For eighty years they lived like this, their wealth and kin increasing, their joy abounding. The eighty years was called the Assembly of the Wondrous Head. By reason of this, the burial of Bran's head was called one of the Three Happy Concealments. For as long as the head remained undisturbed neither plague nor enemy came to the shores of Britain. So ends this branch of the Mabinogi.

The song finished, Myrddin lowered his harp in utter silence. The assembled kings and warriors deemed themselves in the presence of a True Bard and were mute as deer, eyes glowing as if enchanted, and perhaps they were. For certainly they had been held by this tale, and it had worked its subtle spell inside them.

And inside me as well. I, too, felt the tale as a living creation; I knew it to be alive in the way of all true tales. More the dread because of it! For I understood the deeper significance of the song, and I knew what it was the Emrys had sung:

Arthur's troubled reign, and the Enemy's hand in it.

TWELVE

With Cai and Bors before and Arthur behind him, Baldulf s choices were few. Cut off from reaching their ships on the eastern shore, the escaping barbarians turned northward. They hoped to pass unnoticed through one of the many hidden dales and glens that seamed the lowland hills.

They did this and reckoned themselves moire than fortunate, for they happened upon a ruined Roman fortress. There are no less than half a dozen of the old marching-camps in the hills, camps that served Trimontium, the largest stronghold in the region. Nothing remains of Trimontium save a hump in the grass near the Twide, but the smaller forts were made of stone and withstood the wind and weather. It was one of these that Baldulf found – Caer Gwynnion, the White Fort. Though the wooden gates were long gone, those solid stone walls still commanded the dale below.

The second day after the battle, Cai's forces joined us. We broke camp the next morning and marched north up the dale of the Aloent towards Caer Gwynnion. In all we were lighthearted: our forces were replenished, the foe was in retreat, and our prospects for a decisive victory and an early return to the south good. So we passed along the green-sided hills and the rushing water, and sparkling lark song filled our ears. What could be better?

We had never attacked a Roman fort before. And although we knew well how to defend one, assault is a different matter. Small wonder the Celts of old never won a war. Even in ruins, those strongholds are devilishly difficult to defeat.

Indeed, the barbarians learned a new tactic. Nevermore did we face them in the field – they knew they could not win there! After Celyddon the fighting would be from behind the sheltering walls of a fortress.

The Angli had been deserted by their allies. The Picti had long since fled the battle and had vanished into their high moorland wilderness. The Irish, all that remained, had gone home. Only Baldulf and his kinsmen, Ebissa and Oesc, were left with their host – now pared to fewer than thirty thousand.

The British host had diminished, too. We numbered little more than ten thousand: two thousand horse, and the rest on foot. But a good few of those were fresh troops, who had been with Cai and Bors. These had seen no fighting yet, and were eager to win their mead portion and a share of the plunder.

The siege of Caer Gwynnion commenced on a cold, windswept day of the kind that come so frequently and suddenly in the north. Light rain whipped at our faces. The trails became slippery with mud. The horses and wagons were left behind in the valley below, where Arthur directed the camp to be established. An ala in full flying gallop is not much use against the stone walls of a fortress.

We were not foolish enough to storm the walls unaided. That is madness and defeat, as anyone knows. So Arthur turned his memory back to the same Romans who had built the fortress, adopting a tactic the legionaries used with unrivalled success against the timber hill forts of the Celts. We laid siege to the stronghold, and then set about constructing battle machines.

Myrddin's knowledge served us here, for he knew how such machines should be made, and he directed their construction. We made a wheeled tower with a doorway slightly higher than the walls of the fortress. We also built an onager with which to hurl stones into the walls and yard.

The machines were made of timber that had to be dragged up from the dale below by horse. It was slow and tedious work, but in five days they were finished and the battle could begin in earnest.

When the barbarians saw the tower erected they set up a hideous howl. But when the first stones began streaking from the sky like comets, they screamed in rage and frustration. They stripped naked and ran along the tops of the walls, presenting themselves openly, hoping to draw us into range of their axes and hammers and stones.

But Arthur remained unmoved. He commanded that no man should approach the walls and we all stayed well back and let the war machines do their work. We kept the stones flying day and night, moving the onager continually, so that the enemy could find no safe refuge within the walls.

Within three days they were well battered and hungry. When the seventh day had passed, they were weak and stupid with hunger. Then did Arthur order the tower to be wheeled to the wall. The best warriors were inside the tower, led by Cai, who demanded the privilege of directing the battle.