To Lure Young Readers, Nonfiction Writers Sanitize and Simplify

Of all the horrors Louis Zamperini endured during World War II — a plane crash into the Pacific, 47 days stranded at sea, two years in a prisoner-of-war camp — the one experience that truly haunted him was when a Japanese guard tortured and killed an injured duck.

The episode, recounted in Laura Hillenbrand’s best seller “Unbroken,” also traumatized many readers, Ms. Hillenbrand said. So when she was writing a new edition aimed at young adults, she left that scene out.

“I know that if I were 12 and reading it, that would upset me,” Ms. Hillenbrand said.

Inspired by the booming market for young adult novels, a growing number of biographers and historians are retrofitting their works to make them palatable for younger readers. Prominent nonfiction writers like Ms. Hillenbrand, Jon Meacham and Rick Atkinson are now grappling with how to handle unsettling or controversial material in their books as they try to win over this impressionable new audience.