Richard Adams, the bestselling English author best known for his hugely influential 1972 debut novel Watership Down, which has been adapted numerous times, including the acclaimed 1978 animated film and a 1990s animated series, has died. He was 96.

“Richard’s much-loved family announce with sadness that their dear father, grandfather, and great-grandfather passed away peacefully at 10pm on Christmas Eve,” said a message posted today on Adam’s official website.

A quote from his most famous novel accompanied the announcement – “It seemed to Hazel that he would not be needing his body any more, so he left it lying on the edge of the ditch, but stopped for a moment to watch his rabbits and to try to get used to the extraordinary feeling that strength and speed were flowing inexhaustibly out of him into their sleek young bodies and healthy senses.”

“‘You needn’t worry about them,’ said his companion. ‘They’ll be alright – and thousands like them.'”

Adams famously carved out one of the greatest second-acts in literary history, establishing himself as an important talent at age 52 after a career spent in civil service. Born in 1920 in Wash Common near Newbury, Berkshire, England, Adams initially intended to study history, attending Oxford for two years until he was drafted into the British Army during the second world war. Adams never saw combat but served as a Brigade liason in the Royal Army Service Corps in Palestine, Europe, and east Asia. Following his wartime service, Adams returned to Oxford and, after graduation in 1948, joined the British civil service.

He eventually became Assistant Secretary to the Ministry of Housing and Local Government, which would eventually become part of the Department of the Environment, and stayed on this career path for more than two decades. Though he began writing fiction in his spare time, he remained unpublished and could easily have retired as a public servant. That changed, however, thanks to his daughters.

While on a road trip in the late 1960s, Adams had begun telling his daughters a made-up story about a group of rabbits escaping their doomed warren. As their enthusiasm for the story grew, Adams added more details, eventually creating a complex mythology and culture for his fictional rabbits. As he told it in later interviews, his daughters insisted he publish his stories as a book. After two years, he completed the book: Watership Down.

The story follows Hazel and Fiver, two littermates low on their warren’s hierarchy who lead a group of other outcasts on an epic quest to establish a new home safe from the threat of human beings. Along the way, they encounter several other groups of rabbits, evade both man, beast, and even fellow rabbits trying to kill them, ultimately triumphing despite incredible risks and devastating loss.

Watership Down was, at first, a hard sell. Rejected by four publishers and three agencies, it was Rex Collings who agreed to publish it – to immediate success. Hailed for reinventing the genre of fiction written from an animal’s point of view, Adams created a detailed, densely crafted culture and mythology for his fictional rabbits whose intricacy, complexity and internal consistency is rivaled only by J.R.R. Tolkein’s Lord of the Rings universe. It was also praised for its realistic characters and indeed, many of the book’s colorful figures were inspired by people Adams had known, particularly during his World War II service.

The book would quickly sell more than a million copies and became cultural sensation. And, much like Tokein’s works, the novel’s fictional “lapine” language added new words and concepts to the English language, most notably “Tharn”, which means “being frozen in terror”. It would eventually win the Carnegie medal and the Guardian children’s prize.

Of course, Watership Down is probably best known today for the 1978 animated adaptation – an adaptation still joked about for being somewhat terrifying to kids expecting a charming tale of rabbits and instead getting an epic filled with dangers and bloody battles. Directed by Martin Rosen and John Hubley and written by Rosen, the film featured the voices of John Hurt, Richard Briers, Michael Graham Cox, and Harry Andrews in a chilling performance as the book’s primary villain, rabbit dictator General Woundwort.

While a success in British theaters, it flopped in the United States but has since become a cult classic. Numerous other adaptations have followed, with a $100 million BBC/Netflix adaption starring James McAvoy, Nicholas Hoult, John Boyega, and Ben Kingsley due out in 2017.

Adams wrote nearly 20 other works of fiction and nonfiction. Among them, his 1977 novel Plague Dogs, about two dogs who escape an animal testing facility. It was adapted as an animated film in 1982, written and directed like Watership Down by Martin Rosen. Other works include his 1988 historical novel Traveller, and his 1996 short story collection Tales from Watership Down.

Among his other achievements, Adams was once a writer-in-residence at the University of Florida and later at Hollins University in Virginia; he received the inaugural Whitchurch Arts Award for inspiration in 2010; and was given an honorary doctorate by the University of Winchester.