Grace Kelly had a life that could only be described as a fairy tale: She left behind an enviable career in Hollywood along A-list celebrities to become the Princess of Monaco by marrying Crown Prince Rainier III in 1956. At age 52, however, the story turned tragic.

Following her tragic car accident, tabloids ran wild as her surviving daughter reported conflicting reports of her mother’s final moments. New theories about her demise were formulated every day. Only recently unearthed details shed light on what really happened on that fateful September day.

On September 13, 1982, Princess Grace was headed back to Monaco from the royal family’s country home, Roc Agel, located just across the French border. Towering above Monaco at 3,766 feet, the roads surrounding the area are famously steep and narrow.

Traveling with her daughter Stéphanie, the two were carrying dresses and clothing in boxes that took up the entire back seat. Although the chauffeur offered to drive, the Princess insisted it would be more efficient if she drove, since the backseat was full.

It was well-known that the Princess was not a fan of driving, so why she insisted on taking her and her daughter alone was a little strange. Nonetheless, the two set out down the mountain in their green Rover 3500.

The road that leads from the country residence down to the Moyenne Corniche, which takes you into Monaco, is called the D37. About two miles from La Turbie, there is a particularly steep, 150 degree turn in the road, and that’s where things went awry.

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The car carrying Princess Grace and her daughter missed the turn completely, going through a retaining wall and tumbling 120 feet through tree branches and brush before landing in a densely forested area on the slope.

Both women were jostled to the backseat of the car as it flipped down the slope, but Stéphanie survived the accident with a broken collarbone, ribs, and hairline cervical fractures. Her mother, however, would not be so lucky.

But how exactly did the car go off the cliff? Multiple theories have surfaced due to conflicting eyewitness reports. A local bystander named Sesto Lipio claimed that he saw young Stéphanie, who was unlicensed at the time, in the driver’s seat.

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This theory was supported by the fact that, after the car had landed, Stéphanie exited the totaled car from the driver’s side. Furthermore, her mother, who was alive immediately after the crash, just unconscious, was found in the back seat.

Was she be trying to cover for her daughter? The rumor was never substantiated since other eyewitnesses did report seeing Princess Grace in the driver’s side. In 2003, Stéphanie went on record to squash the rumor once and for all.

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“I was not driving,” she told Paris Match. “I was thrown around inside the car like my mother… The passenger door was completely smashed in — I got out on the only accessible side, the driver’s.” But the case wasn’t closed.

Stéphanie’s recount of the accident’s details came under question, as the only person in her family she ever discussed it with was her older sister Caroline. She famously said in an interview, “I still can’t talk to my dad about it because I know it hurts him and I don’t want to do that.”

Some have wondered whether she had been so traumatized by the event that she had blocked it out of her memory, but she insists otherwise. “I remember every minute of it,” she said. “It’s only in the last few years that I’ve been starting to cope with it.”

Nonetheless, Stéphanie’s account of the crash has not changed since the day it happened: Her mother was in a panic as they lost control of the car, saying that the breaks weren’t working. To stop the car, Stéphanie put the gear in park.

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This was supported by the investigation, which confirmed that the car was indeed found in the park position on the slope. So was there a mechanical malfunction with the breaks?

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Not according to the experts. In fact, eyewitnesses claimed to see the car swerve violently before accelerating off the cliff. Stéphanie says her mother may have accidentally mixed up the break for the accelerator. Medical reports explained how.

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Princess Stéphanie recalled her mother complaining of having a headache. As it turns out, just moments before the crash, her mother’s headache got worse, as a sudden sharp pain caused her to momentarily black out. That wasn’t the end of it.

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After losing consciousness for a few seconds, she seemed to snap back to life, aware that she was driving, but disoriented. She accidentally slammed on the gas instead of the breaks, sending the car careening over the edge. She had just experienced a mild stroke.

Medical examinations after the accident found evidence of a mild cerebral hemorrhage, causing her to lose consciousness for a few moments. The tragic crash then caused another hemorrhage, from which she would never regain consciousness.

Princess Grace of Monaco was declared to be fully brain dead the following evening and was removed from life support. Her funeral was a lavish celebration of her life and achievements, attended by Cary Grant, Nancy Reagan, and Diana, Princess of Wales.

Despite being the subject of rumors and theories for years after the event, the medical and scientific evidence point to the clearest explanation we have for the accident. Princess Grace of Monaco will always be remembered as the epitome of Hollywood glamor and European elegance.

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1. Grace Kelly always wanted to be an actress, a dream her parents didn’t exactly support. Rumor has it that her father, John, thought the acting profession was merely a “slim cut above streetwalker.” 

2. Acting was actually in Grace’s blood: her Uncle Walter was a vaudeville star and her other uncle, George, was a Pulitzer Prize-winning screenwriter. Why did Grace’s father detest acting so much when it was already in his family? 

3. Grace came from a wealthy and influential family, in part because of her parents’ athletic accomplishments: John won three Olympic gold medals, and Grace’s mother, Margaret, taught athletics at the University of Pennsylvania. So much talent in one family!

4. The athleticism in the family didn’t end with Grace’s parents. Her brother, John Jr., competed as a rower in four Olympic games and even won a bronze medal in 1956. He ended up giving his medal to Grace as a wedding present!

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5. Grace was accepted into the American Academy of Dramatic Arts, but she had difficulty finding acting gigs. Grace eventually found work as a model and was on the cover of magazines like Cosmopolitan. She even appeared in some cigarette ads. 

6. Grace almost didn’t make it as an actress. All available spots at the A.A.D.A. were filled when she applied, and they almost didn’t let her interview. Without the influence of her Uncle George, she probably wouldn’t have been accepted.

7. Would it come as a surprise that Grace isn’t British? Her measured way of speaking was really just the result of vocal training from her coaches at the A.A.D.A., who thought she needed to rid herself of her Philadelphia accent. 

8. It’s hard to imagine Grace Kelly as anything other than beautiful, but that’s how her friends and family first saw her. One of her childhood friends said Grace was “nothing glamorous” growing up — imagine their surprise when she graced the cover of Cosmo!

9. Just because Grace wasn’t gorgeous growing up doesn’t mean she wasn’t talented. Her peers at Stevens School — a private high school — printed “Miss Grace P. Kelly — a famous star of stage and screen” in the yearbook.

10. Things sure were different back in the ‘50s: when Grace first moved to New York, she lived in the Barbizon Hotel for Women, a hotel that forbade men from going above the main floor. 

11. Most of the high-profile men she dated started out as her co-stars: Gary Cooper was her co-star in High Noon, Clark Gable was in Mogambo, and Ray Milland was in Dial M For Murder. The problem? The men were usually already married!

12. Back in the day, there was no greater honor than having your name appear on a stamp. Grace Kelly received this honor twice: in the U.S. as “Grace Kelly” and in Monaco as “Princess Grace.” 

13. In 1955, Grace won an Oscar for her role in The Country Girl, though she could have won an additional award had she not dropped out of the film On The Waterfront whose star Eva Marie Saint won Best Supporting Actress that same year.

14. When Grace decided to marry Prince Rainier of Monaco, it came at the expense of her acting career. She was 26 when she retired from acting, and though she was offered roles for the rest of her life, she never accepted.

15. So, who is this Prince who captured Grace’s heart? The two met at the 1955 Cannes Film Festival and both sensed a connection. After writing love letters to one another, the Prince met with Grace’s family and proposed.

16. Who said romance is dead? Before marrying Prince Rainier, Grace had to do three extremely old-fashioned things: renounce her American citizenship, take a fertility test, and pay a dowry of $2 million.

 17. Grace Kelly’s wedding dress was truly something to behold. It was made by Academy-Award winning designer Helen Rose and had 25 yards of silk taffeta and 100 yards of silk net. The veil had thousands of pearls sewn into the delicate fabric.

18. Despite being a Prince, Grace’s husband apparently felt uncomfortable about his wife’s former acting career — so much so that he banned all of her films from being played in Monaco. How could he ban such a huge part of Grace’s life?

19. Princess Grace didn’t always conform to princess-y stereotypes. Her longtime assistant said that Grace was never “stuffy” and that “she had a mischievous sense of humor.” She even wore trousers — but only around the house. 

20. Despite Prince Rainier’s distaste for Grace acting in films, the couple apparently worked on an independent film together, Rearranged, when ABC executives became interested in the premise. But when Grace died unexpectedly, the film was never released. 

21. At Grace’s funeral, James Stewart gushed about the Princess, calling her “the nicest lady I ever met.” Judging by the other attendees — Cary Grant, Nancy Reagan, and Diana, Princess of Wales — the feeling must have been shared by many.