‘There were fault lines, on both the Moorish and Christian sides,’ Sihtric said. ‘Abd al-Rahman always had trouble with the Berbers. One Berber general called Munuza managed to carve out an independent kingdom for himself in northern Spain, bordering Gaul. And his neighbour in Gaul was the Duke Odo of Aquitaine, who had nominally pledged allegiance to the French kings, but like Munuza craved his own independence. Both pebbles in the shoes of their respective rulers, you see.

‘Well, Abd al-Rahman had a tidy mind. He shook out both these pebbles. He killed Munuza, and then crossed the mountains into Aquitaine. Odo’s forces were defeated, and Abd al-Rahman, leading his army in person, drove forward, thrusting deep into Gaul. Fifteen thousand men he had, to carry out the usual burning, looting, massacring, enslavement and so forth. And he advanced to within two hundred miles of Paris, to a place called Poitiers.’

‘I know it. Not far from the sanctuary of Saint Martin of Tours.’

‘And there, history turned,’ Sihtric said. ‘The Muslims were at the door to the “Great Land”, as they called it, of western Europe. Perhaps they could go further - perhaps they could advance all the way to Constantinople.

‘But there, on the Roman road north of Poitiers, al-Rahman faced the army of the Frankish king, the last significant obstacle between the Muslims and all Europe.’

Orm knew the story. ‘Charles Martel. The Hammer.’

‘Well, Charles became known as “the Hammer” only after his great victory, after he saved Europe for Christendom. A story told to every young Christian warrior since! But it need not have been so. This is where we come to the rent in time’s tapestry, Orm. This is what happened . . .’

Odo of Aquitaine, his army defeated by the Moors, his cities stormed, his people slaughtered or enslaved, was in despair. His only possible ally was Charles of the Franks, on whom Odo had previously made war himself. Odo considered surrendering to the Muslims, who might prove more merciful to him and his family than the Christians.

Sihtric said, ‘He seems to have been a poor sort of a man, and a worse ruler. But then he got help. A monk turned up at Odo’s camp. He rode only a humble ass, like Christ entering Jerusalem, and carried nothing, no food, not even a bottle of water. He relied for his life on the Christian charity of the folk whose lands he crossed. He was a peculiar type, too well-fed to be a monk - and well-spoken, with a peculiarly accented Latin on his lips. He impressed with minor miracles - fortune-telling, an ability to predict bad storms and harsh winters, that sort of thing. He said his name was Alfred, he was from the famous monastery of Lindisfarne in England, and he had a message from Christ for Odo.’

‘He was al-Hafredi.’