“DEATH OF KINGS.” By Bernard Cornwell. Harper. $27.99.

Bernard Cornwell takes us to a moment in the English isles’ misty past when the dream of unity was a fragile, endangered thing. His novel “Death of Kings” is set in the late 9th century, a time of ferocious division and Danish domination that Cornwell has claimed as fictional territory in his “Saxon Chronicles” series.

“In the winter of 898, there was no England,” says Uhtred of Bebbanburg, a mighty warrior at the novel’s center. “There was Northumbria and East Anglia, Mercia and Wessex, and the first two were ruled by the Danes, Wessex was Saxon while Mercia was a mess, part Danish and part Saxon.”

Uhtred can well sympathize with this sorry state of affairs. His own sense of identity is just as divided: “And I was like Mercia because I had been born a Saxon, but raised as a Dane.” In the dangerous maneuvers to dominate, then, whose side should Uhtred support, Saxons or Vikings?

Early on, the dying King Alfred and his son Edward call upon Uhtred to unite the Saxon lands against their common enemy. But why? Uhtred wonders. “Why ally myself to a man destined to fail?” he says, thinking of Alfred. And yet, Uhtred is loyal to them, struggling against several Viking marauders as well as traitorous actions that end up pitting Saxons against each other.

Cornwell’s story reminds us of the perilous condition of nationhood and identity in those distant times, and of Viking power that, if it had remained unchallenged, could have turned the British Isles into some kind of Norse colony or outpost. Though readers have the benefit of historical hindsight, the players in Cornwell’s story certainly have no idea how God (the Norse or Christian version) will determine their fates.

Decisive moments hinge on mighty personalities, and Uhtred is one of these: In fact, he bears the qualities of a king, not the warrior who serves one. He’s passionate in battle, passionate about his love for Aethelflaed, Alfred’s daughter (she proves to be an invaluable commander in the field), and passionate about the land he calls home.

Cornwell convincingly sets Uhtred’s adventures in the context of historical events (he is not entirely a fictional invention, by the way, but is based on an actual ancestor of the author). He also gives us an awful sense of the conditions of 9th-century warfare. No place is “more terrible than the shield wall,” Uhtred says of the way soldiers lock their shields together to fend off the charges of their enemies. As he says this, he touches an object on his necklace that some could mistake for the cross of Christianity, though it isn’t one. “It is the place where we die and where we conquer and where we make our reputation. I touched Thor’s hammer, prayed that Edward was coming, and readied to fight.”

Before joining a shield wall, then, a stiff drink of ale or mead might be a good idea.

The novel climaxes with the rebellion of Aethelwold, a cousin to Edward, and Cornwell renders the final battle with shield-splintering detail. The Anglo-Saxon Chronicles might be “our best source for the events of the period,” including this rebellion, Cornwell writes in a historical note, but the chronicles also only “give us the bare bones of history, without much detail or even explanations for what happened.”

A veteran of the best-sellers lists (especially for his tales of Sharpe, an English soldier in the Napoleonic era), Cornwell adds meat to these bare bones, and he knows how to move the story along with clean, clear, well-oiled prose.

It’s the sort of story that can be enjoyed simply for its plot, but it also supplies interesting information about Mercia and Wessex or the strains on a lord’s finances to maintain and feed his troops. Far smoother reading on the topic than you’ll find in a musty old history book.