“I probably will,” I said. “He’s a Norseman and a pagan. But that makes him your enemy, and he’s an enemy living on your land.”

“And he pays us tribute. And tribute weakens the payer and acknowledges his subservience.”

“Cheaper in the long run,” I said, “just to kill the bastards.”

“Ingilmundr swore on his gods to live peaceably with us,” Æthelstan continued, ignoring my comment.

I leaped on his words. “So you trust his gods? You accept they are real?”

“They’re real to Ingilmundr, I suppose,” Æthelstan said calmly. “Why make him take an oath on a god he doesn’t believe in? That just begs for the oath to be broken.”

I grunted at that. He was right, of course. “But no doubt part of the agreement,” I said scathingly, “was that Ingilmundr accepts your damned missionaries.”

“The damned missionaries are indeed part of the agreement,” he said patiently. “We insist on that with every Norseman who settles south of the Ribbel. That’s why my father put a burh at Mameceaster.”

“To protect missionaries?” I asked, astonished.

“To protect anyone who accepts Mercian rule,” he said, still patient, “and punish anyone who breaks our law. The warriors protect our land, and the monks and priests teach folk about God and about God’s law. I’m building a convent there now.”

“That will terrify the Northmen,” I said sourly.

“It will help bring Christian charity to a troubled land,” Æthelstan retorted. His aunt, the Lady Æthelflaed, had always claimed the River Ribbel as Mercia’s northern frontier, though in truth the land between the Mærse and the Ribbel was wild and mostly ungoverned, its coast long settled by Danes who had often raided the rich farmlands around Ceaster. I had led plenty of war-bands north in revenge for those raids, once leading my men as far as Mameceaster, an old Roman fort on a sandstone hill beside the River Mædlak. King Edward had strengthened those old walls and put a garrison into Mameceaster’s fort. And thus, I reflected, the frontier of Mercia crept ever northward. Ceaster had been the northernmost burh, then Brunanburh, and now it was Mameceaster, and that new burh on its sandstone hill was perilously close to my homeland, Northumbria. “Have you ever been to Mameceaster?” Æthelstan asked me.

“I was there less than a week ago,” I said ruefully. “The damned monk who lied to me left us at Mameceaster.”

“You came that way?”

“Because I thought the garrison would have news of you, but the bastards wouldn’t talk to me, wouldn’t even let us through the gate. They let the damned monk in, but not us.”

Æthelstan laughed. “That was Treddian.”

“Treddian?”

“A West Saxon. He commands there. Did he know it was you?”

“Of course he did.”

Æthelstan shrugged. “You’re a pagan and a Northumbrian and that makes you an enemy. Treddian probably thought you were planning to slaughter his garrison. He’s a cautious man, Treddian. Too cautious, which is why I’m replacing him.”

“Too cautious?”