'God's honour! That is the truth. I do heed the risk. Someone must.' Cai folded his arms across his chest, glowering out from beneath his copper-coloured brows.

'What impossible thing is he proposing this time?" Bedwyr laughed as he sat down on the bench. I settled beside him; Merlin remained standing.

Cai, a pained expression pinching his ruddy features, put up his hands. 'Do not ask me to repeat it. I will not.'

Arthur gazed placidly at Cai and then shrugged. 'Perhaps he is right – it cannot be done.' He turned to Bedwyr and Merlin. 'Well, wise advisers? Advise me wisely, or Morcant will.'

We all looked at one another, silently calculating our chances of surviving this day.

'Well,' said Merlin after a moment, 'perhaps it is a day for impossible feats. Who knows?'

'It seems we have no other choice,' muttered Cai.

'Are we to know this impossible plan of yours?' demanded Bedwyr. 'Speak it out.'

'I was only thinking,' began Arthur slowly, 'you know how these hills catch the echoes… '

The sun stood directly overhead and there was'still no sign of Morcant's war host. Scouts had been dispatched and had returned with confirmation that indeed a force of three hundred or more were approaching along the coast. They had crossed the Ebbw and were making for Glyn Rominw – the vale of the Rominw river.

The deep glen circled Caer Melyn, describing a half-moon arc to the east before curving away to meet Mor Hafren just to the south. Any attacking army would find it a natural roadway straight into the heart of Arthur's realm.

The young Duke knew the vale for what it was, and knew his enemies would regard it a weakness. But part of Arthur's genius lay in his remarkable ability to read the land.

He had only to see a place once to know it – each hill and hollow, every freshet and stream, every dingle and dell, rock cliff and standing stone. He knew where it was safe to ford, where the ground cover was thickest, where the hidden trails met and where they led. He knew all the ancient tracks and ridgeways, where men might safely ride without being seen, how the fields of the various realms were laid, which height would afford protection, which lowland a hiding-place, where natural defences could be found, where the land favoured attack, or retreat, or ambush…

All these things and more Arthur could read in the fold and crease of the earth. The land spoke to him, readily revealing its secrets to his quick eyes.

This is how I came to be squatting on a hillside overlooking a ford on the Rominw, holding a blackthorn bush before me, surrounded by a company of warriors, each similarly hidden. Across the glen, Cai, with another company, lay hidden behind a low, grassy rise. And to the north another company; to the south another, and so on all along the vale.

Tune passed. I sat watching cloud shadows on the hillside opposite me or gazing south along the curving length of the river, listening for the sound of the approaching warband and wondering what detained them – thinking that perhaps they had not chosen Glyn Rominw after all.

The wind had shifted to the north, making the sound of Morcant's approach more difficult to hear – if indeed he had entered the vale. What was taking the old lion so long?

Perhaps he had continued on along the coast to come at us out of the west. Perhaps he had forded the Rominw and crossed back to the east to come inland along one of the smaller streams. Perhaps he had – the thought never finished itself, for at that moment I heard it: the quick, rolling drum of horses hooves upon the earth.

I craned my neck to the south and peered through the branches of my blackthorn bush. A moment later I saw them, Morcant's forces moving through the glen. They came on in a loose pack; there were no orderly ranks, no coherent divisions of any sort. They spread across the valley floor in a ragged swarm. More a mob than a force of disciplined men.

That was the pith of it! So arrogant was Morcant, so smug and self-assured, so confident in his superior numbers, he made no attempt at order in his ranks. He meant to overwhelm Arthur's warband – like a wave on the shore, to simply wash over us and crush us with its all-engulfing weight.

I watched the unruly throng stream into the valley below, and anger leapt up, a hot red flame within me. Fool! Morcant esteemed Arthur not at all. So lacking in respect he did not even deem it wisdom to order his ranks. Oh, the insolence was blinding, the pride deafening.

I saw it all and did not care that we were only seventy against three hundred. Blessed Jesu, if we die today, let it be as true warriors with honour.

The first foemen had reached the ford. Some splashed through the stream, others stopped to drink – the ignorant louts. Careless and stupid in their arrogance. My anger burned more fiercely in me.

As soon as the main body of the warband reached the opposite bank, a mighty shout went up, an all-encompassing shout, a shout to shake the roots of the world. 'ALLELUIA!'

I looked and saw Merlin standing alone on the hilltop, arms raised over his head, his cloak loose and blowing. At the very same instant there came an answer from across the glen. 'A-1-l-e-l-u-i-a!'

The echoes rang. 'Alleluia!… Alleluia!'

I joined in the gladdening cry, and the warriors with me on die hillside shouted too. 'Alleluia!'

The shouts were coming from all along the glen now, the echoes pealing like bells, ringing on and on. Alleluia! Alleluia! Alleluia!

The effect was immediate and dramatic. At that first enormous shout, the enemy had halted. The cries of alleluia assailed them from every side. They scanned the hillside for the foe, but saw no one. Now the echoes encircled them, pelting down upon them… Alleluia! Alleluia! Alleluia! Alleluia!

Morcant's host scattered. The main body drove back across the stream into those still straggling behind. Seeing the ford hopelessly blocked, others turned to the hills. A group of twenty broke off, riding straight towards us.

We let them come. Nearer… nearer…

With a mighty shout we threw off the blackthorn branches that hid us. 'Alleluia!'

Up we leapt, sword in hand, striking, pulling the startled riders from their saddles. We struck them to the ground and sent their terrified horses back down the hill into the confused host. I looked across the glen. The same thing was happening on the opposite hillside, as astonished warriors disappeared behind the grassy rise where Cai's men waited.

Shouting, raving, screaming, the vale throbbed with the unearthly and unnerving sound. Morcant's war host, confronted by this invisible, seemingly invincible foe, bolted in chaotic retreat back down the valley.

Seeing this, we ran for our horses, tethered behind the crest of the hUl. But a few heartbeats later we were hurtling down the face of the hill and into the retreating war host. Morcant and Cerdic stood at the ford, their warriors fleeing away like a flood parting around them. They raged at the men, screaming for them to turn and fight.

And then there was Arthur in their midst with his eleven. They had simply appeared, it seemed – sprung to life from the rocks at their very feet, horses and all.

It was too much. Cerdic wheeled his horse and fled after his men. Morcant was too crazy with rage to heed his own danger. He lifted his sword and rode at Arthur. The two met. There was a quick flash of steel and Morcant fell. His body rolled into the stream and the king lay still.

The fight did not end there. We escaped death that day, nothing more.

Though we were all grateful to walk the land of the living, as the sun faded behind the western hills and we returned to the caer we knew that only a battle had been won. We suffered no losses, and only two men wounded. Cerdic had fled with his warband almost intact; he would nurse the injury to his pride for a season and then he would return to avenge his father. Others who thought to gain from the strife would rally to him, and the war would go on.