‘Well, yes, but don’t run ahead of the story, Viking. He might have been killed, for Odo’s troops were by this time cowering from shadows. He did have his wretched ass stolen, slaughtered and eaten by the starving warriors. But he was let live, and was admitted to Odo’s presence. And there he changed Odo’s mind.’

‘How?’ Orm asked.

Sihtric shrugged. ‘I don’t know what he said to Odo. I don’t know what he promised him, what he showed him. But, Viking, if I knew your future, all of it, it would not be hard to manipulate you. Perhaps you can see that.

‘In any event al-Hafredi persuaded Odo that he should not submit to the Moors, and despite his hostility to Charles he should throw himself on the Frank’s mercy and face the Moors with him. And he whispered to Odo how the Moors might be beaten.’

‘And Odo was convinced by this?’

‘He must have been. For that’s precisely what he did.’

So the Moors faced the Franks, that October three centuries past, the future of all Europe at stake. The two forces had been well matched. Charles was a proven war leader, as was Abd al-Rahman. There followed seven days of inconclusive skirmishes and scouting.

At last the combat came. Odo’s weary forces made little difference to Charles’s military strength - but the advice Odo was able to give on how the Moors fought, and how Abd al-Rahman thought, was much more valuable.

‘The Moorish cavalry charged. But Charles’s infantry held their ground. The Muslims were taken aback. They had been used to Christians breaking and running from their advances. In that one moment the battle turned, just as al-Hafredi said it would. And then Charles shocked the Moors by attacking them aggressively.

‘In the combat that followed, Abd al-Rahman was killed. I have always wondered if al-Hafredi had something to do with it - perhaps that drab monkish habit concealed a knife. The Moors were not broken. They could have fought on, but without their leader, they chose to turn away.

‘The battle itself was inconclusive. But it was a crucial day, in all our histories - Bede of Jarrow knew this, in faraway England. The Moors had come a thousand miles north from the strait to Africa. Now at last they had been turned back. And though they continued to raid southern Gaul, they were never to progress so far north again. Why, less than a century later Charles’s grandson Charlemagne was mounting expeditions the other way across the Pyrenees.’

‘Christendom was saved, then. And what became of al-Hafredi? How did his story come down to you?’