As a writer of historical fiction, Bernard Cornwell has produced at least one book every year for more than three decades. What accounts for his extraordinary output? For one thing, he says, “I’m not writing literature.” Literature tackles life’s big questions, while “my books are about killing people.”  In all, his 54 books have sold more than 20 million copies world-wide, covering topics from Stonehenge to the Napoleonic Wars to the American Revolution. Two of his series have been turned into BBC television shows. His latest novel, “The Flame Bearer,” is the 10th in his “Last Kingdom” series, set in 10th-century Northumbria during the making of England.  At the time, the land was divided between two warring factions, a Christian Saxon south and a pagan Viking north. The series follows a character named Uhtred of Bebbanburg, a bad-tempered yet loyal Viking warrior who in the latest book tries to reclaim his family’s castle from a traitorous uncle.  In each of his books, Mr. Cornwell, 72, explains what is fact and what is fiction in a historical note at the end. For 10th-century England, “so much of it is darkness and shadow. We don’t know what happened,” he says. “That’s wonderful, because that means you can start making things up.”  When there’s more of a historical record, Mr. Cornwell tries to describe events as accurately as he can. For his best-known series, about a fictional British officer in the Napoleonic Wars named Richard Sharpe, Mr. Cornwell researched the details of battles down to the buttons on the uniforms the soldiers wore. “It’s not something where Robert E. Lee suddenly has AK-47s at Gettysburg,” he says. “I do think I have a duty not to totally mislead.”  Born in London, Mr. Cornwell was long fascinated by the military. His birth parents were each in the Air Force of their respective countries—his mother was British and his father Canadian. They were together only briefly, and he was put up for adoption as a baby. He was raised by a couple who were part of a religious group, the Peculiar People, that eschewed tobacco, alcohol, movies and modern medicine. As a teenager, he developed a particular passion for the Napoleonic Wars.  Mr. Cornwell tried to join the military but was rejected for being nearsighted. After college, he worked as a teacher and then as a news producer at the BBC. He met his second wife, Judy, an American travel agent, while she was visiting Northern Ireland in 1978.  Mr. Cornwell moved to the U.S. to be with her, but without a green card he couldn’t work. He started writing fiction to try to make some money. In 1980, he met a literary agent at a Thanksgiving Day parade party in New York and followed him around the event until he agreed to read Mr. Cornwell’s novel. He is still with the same agent today.  He became an American citizen in 1998 and now splits his time between Chatham, Mass., on Cape Cod and Charleston, S.C. He says that he hasn’t experienced any problems writing about England and Europe (where his books tend to sell best) from the other side of the Atlantic. “P.G. Wodehouse lived on Long Island and wrote the most English novels ever written,” he says. “C.S. Forester’s Horatio Hornblower series were all written in California, so there’s this long track record of this.” He still goes back to England to visit his daughter from a former marriage and his grandchildren.  Mr. Cornwell only met his birth parents 14 years ago. Trying to enliven a dull interview with a newspaper reporter in Vancouver, he said that he knew his father lived in Canada and that he’d always wanted to find his parents. Soon after the story came out, one of his long-lost cousins approached him at an event in Toronto and told him where he could find his father. Then he met his mother, who had gone on to marry and have more children in England.  These days, Mr. Cornwell has tapered down to writing just one book a year so that he can spend three months acting in summer stage on Cape Cod. Last year he played Prospero in Shakespeare’s “The Tempest.” Next summer, he will be the narrator in Neil Simon’s “The Good Doctor.”  When he’s writing, he usually wakes up around 6:30 and walks his dog, Whiskey. Then he writes until about 5, stopping several times for lunch and walking breaks. At night, he reads—anything but historical fiction. Instead, he likes science, history and police procedurals. Recently, while reading “The Gene” by Siddhartha Mukherjee, he stumbled upon an anecdote about medieval magicians who thought that if you buried human sperm in a dung heap, a little human being would come out. He wrote it down to use in a future book.  He is now working on a new book, which he started in September, though he won’t reveal the details. He feels that he hasn’t made much progress and isn’t sure it will work out. He doesn’t mind giving up on stories that don’t come together quickly. “In that case, it’s much easier to do a quick-and-dirty Uhtred,” he says. “I have all the characters in my head.”  Write to Alexandra Wolfe at alexandra.wolfe@wsj.com
The historical novelist talks about his prolific output, his passion for the Napoleonic Wars and why he likes writing about long-ago events.