Prince Charles and Princess Diana
Prince Charles and Princess Diana are pictured at an official event during their first royal Australian tour 1983 in Newcastle, Australia. Patrick Riviere/Getty Images

Long before affairs and other scandals plagued Prince Charles and Princess Diana’s marriage, the Prince of Wales was a single man searching for a wife. While it appeared he found the perfect woman when his engagement to Diana was announced, it turns out their marriage may have never happened if Prince Philip didn’t give his son an ultimatum.

In the book “The Duchess: The Untold Story,” author Penny Junor claimed while Prince Charles was courting Princess Diana, he may have misunderstood his father’s demand for him to make a decision about their relationship.

“The Duke of Edinburgh wrote to his son to the effect that he must make up his mind about Diana,” Junor wrote.

However, the royal author claims the demand was more for Diana’s peace of mind, rather than pushing Charles into a marriage. Junor implied Philip thought it was best for Charles to, “either marry her or let her go; with all the media madness, it was not fair to keep her hanging on, and he was in danger of tarnishing her reputation.”

Instead, Prince Charles thought his father was telling him to propose. “[Charles] wasn’t yet certain, but Diana was so perfect in so many ways that he couldn’t risk losing her,” Junor revealed.

“Charles was preparing to propose marriage to a girl he barely knew as a result of a misinterpreted memo from his father. It could not have been more catastrophic,” the author explained.

Despite Philip’s goal to simply set Diana free from unnecessary attention, Charles thought he had no choice, but to marry a stranger. “The Prince saw it as an ultimatum to marry, although others who saw the note think this was the wrong interpretation.”

Prince Charles and Princess Diana married in 1981 and had two children together, Prince William and Prince Harry. In 1996, the couple finalized their divorce and Charles went on to marry Camilla Parker Bowles.