During medieval times, Roger Federer's killer backhand might have been considered, well, actually killer. The elegant and graceful game of tennis was responsible for so many royal deaths that it could make an executioner jealous.
Start with Louis X of France. One of the 14th century's most avid players of jeu de paume (an early, racquet-less form of tennis that involved hitting the ball with the palm of the hands), Louis famously constructed the world's first modern indoor tennis courts, allowing him to play his beloved sport year-round. In June 1316, Louis played a heated game and reportedly became extremely dehydrated. To cool down, the panting king glugged a giant urn of chilled wine … and promptly died.
The cause of Louis X's death—whether from alcohol poisoning, overheating, or some preexisting condition—is unknown. We do know, however, that the 26-year-old monarch left no male heirs (besides a posthumous infant son who died within the week), and when his brothers likewise failed to have boys, the Capetian dynasty ended, creating conditions that eventually led to the Hundred Years' War.
The next tennis-related fatality struck in 1437. Known for having a physique of "excessive corpulence," King James I of Scotland supposedly played the game to keep his bloating belly in check. Problem was, he kept losing tennis balls to a pesky sewer drain. (As a contemporary put it, "[T]he balls that he played with oft ran in at that fowle hole.") To fix the problem, James had the sewer sealed.
Three days later, a group of assassins crept into King James I's lodgings. Hearing them approach, James lifted a floorboard and plunged into the sewer, hoping to make his exit by crawling out the exterior pipes. Unfortunately, the escape was the same pipe he had sealed. James was trapped and thusly murdered.
Half a century later, the deadly sport struck again when an overexcited King Charles VIII of France met his maker after rushing through a poorly maintained castle in an effort to see a highly anticipated game of tennis. According to The Memoirs of Philip de Commines:
"[He] took his queen … by the hand, and led her out of her chamber to a place where she had never been before, to see them play at tennis in the castle-ditch … It was the nastiest place about the castle, broken down at the entrance, and everybody committed a nuisance [that is, peed] in it that would. The king was not a tall man, yet he knocked his head as he went in."
Hours later, the 27-year-old king collapsed and died.
The list of tennis-related demises goes on. In 1751, King George II's son Frederick, the Prince of Wales and heir apparent, died of a reported lung abscess. (Doctors at the time blamed a tennis or cricket ball that had earlier struck his chest.) And Queen Anne Boleyn was watching a tennis match in 1536 when she received orders to present herself to the Privy Council, which informed her of her ensuing execution.
As Boleyn was being beheaded, her husband, King Henry VIII, attended to other duties. As one version of the events goes, he was busy playing a leisurely game ... of tennis.