And yet Artorius had made great changes. To those old Celtae forces, fighting had been ritualistic. Armies would draw up to face each other, would make a racket and an elaborate display, and only small teams of champions would be sent to do battle together. And they couldn’t sustain a long campaign: Celtae armies, recruited from local farmers, had been forced to disperse when the crops needed harvesting. All that had had to change when the Romans had come with their propensity for pitched battles with decisive outcomes: The Celtae had quickly learned the techniques of long campaigns and massed slaughter.

Now the Romans were gone, but their lessons lingered. Artorius had been assiduous. He had even picked Regina’s brains over what she could remember of Aetius’s reminiscences of the comitatenses. Now Artorius’s warriors were an effective and mobile fighting force, just as capable as the Romans’ of waging a pitched battle—and of mounting a summer-long campaign.

But Artorius’s practices were increasingly laced with a primitive darkness.

Regina knew the old beliefs, spouted by Myrddin and others. To take the head of your enemy was to possess his soul, so when these Saxon heads were mounted on stakes around the walls of the hill fort their souls would keep out danger. Regina wasn’t sure how much of this Artorius believed, but she could see how he used its symbolism, working on both friend and foe, to cement his victories.

Regina lived with barbarians, and was the mistress of a warlord. But she could live with that until, as she always promised herself, things got back to normal, and the Emperor returned with his legions to sweep out the Saxon marauders, dissolve the petty native kingdoms—including Artorius’s—and restore Roman dignity and order, so that this brief and bloody interval would come to seem no more than a bad dream.

Now here came the riothamus himself, at the head of his army.

At the gate, Artorius embraced Regina. He was hot, his armour scuffed, and she could smell the stink of his horse. “We have won great victories, my Morrigan. Everywhere the Saxons lie slain, or they run away at the sound of our trumpets. They are falling back to their fastnesses in the east, but perhaps next season—”

“Your deeds will live on for a thousand years, riothamus.”

He cocked an eyebrow. “You sound like Myrddin. However I hear a ‘but’ in your voice . . .”

“But your collection of severed heads would have appalled Vespasian.”

His face clouded. “The Caesars aren’t here. They abandoned us to the Saxons. I do what I have to do. In fact—” Artorius turned speculatively, looking east, the direction of Europe and the rump of the Empire. “Perhaps, in fact, now that we are strong, we should be planning what to do about the Caesars and their betrayal of Britain.”