David Buchan/Getty Images Charles, 9th Earl Spencer
Charles Spencer tackles a screen-worthy chapter in royal history with his new book.
In The White Ship, historian and 9th Earl Spencer explores a disaster that changed the course of the monarchy forever: the maritime disaster in 1120 that killed 300, including King Henry I's heir, William Aetheling.
"It is Game of Thrones meets Titanic," Spencer tells PEOPLE Royals in the new fall issue, on newsstands now. "And once people get over going back 900 years, it's a very recognizable story with very fallible human beings."
In the book, which is already a bestseller in the U.K. and is set for release in the U.S. on October 19, Spencer examines the shocking brutality of Henry I, whose success at maintaining safety for his subjects at home came with the cost of his fearsome tactics with foes.
— Charles Spencer (@cspencer1508) September 1, 2021
"If you wanted to be a successful ruler in Europe in the 12th century, you had to make people scared of you," says Spencer.
Meanwhile, his heir William Aetheling was a fun-loving 17-year-old when his reckless partying led to the devastating shipwreck.
Henry II was crowned King of England in 1154. His reign marked an end to the turmoil that had followed the White Ship disaster. The grandson of Henry I, his Plantagenet bloodline would occupy the throne until the Tudors overthrew and replaced them in 1485. pic.twitter.com/O0jG9Jas0m
— Charles Spencer Bookshop (@cspencerbooks_) July 21, 2021
"It's the medieval version of drunk driving," says Spencer, "where the teenagers get riotously drunk and then encourage the crew, to whom they're entrusting their lives, to join in the drinking. And guess what? They hit a rock, the ship goes down and all but one person on board drowns.
For more royal insights, including glamorous photos and inside stories, pick up a copy of PEOPLE Royals, on newsstands now!
"It's an incredible lesson," he continues. "The king, who insisted on going on his own ship with the grown-ups and then left his teenage son on board the most exciting ship, the White Ship, was tempting fate. It's certainly not his fault, but you can see how it happened."