Prince Charles allegedly married Princess Diana because he was frightened of his father, Prince Philip. A new book cited that the Duke of Edinburgh pressured his son, the Prince of Wales, to find a bride so he was forced to propose to Lady Di.

Prince Philip Revealed author Ingrid Seward wrote that Prince Charles confided in friends over the pressure to marry Diana. Apparently, Prince Philip told his son, during his short courtship with the future Princess of Wales, that he cannot string along a 19-year-old girl when Charles is of the marrying age at 31.

More pressures to marry Diana came from the press, which has labeled her as "the next queen." Prince Philip allegedly told Prince Charles that he needed to act on this -- marry Diana or let her go and look for another bride. According to History Extra, Prince Philip even wrote a memo to his son. Prince Charles chose the first option out of fear towards his father.

Seward also revealed that Lady Diana was originally set up for Prince Andrew, Prince Charles' younger brother. Friends of the princess thought that their personalities were more suited for each other and Andrew's age was closer to Diana.

As a younger child, Princess Diana frequently spent time with Prince Andrew and the Queen's youngest son, Prince Edward, at Sandringham since her father, John Spencer, worked for the royal family. Only, Lady Diana was keener on a courtship with Charles than his brother.

Charles and Diana ultimately ended up married in 1981. A year later, they welcomed their first-born son, Prince William. In 1984, their second-born, Prince Harry, arrived.

However, Charles and Diana's had marital problems from the beginning. According to reports, the princess struggled with mental health issues because of her unhappy childhood while Charles had been seeing Camilla Parker-Bowles, an ex-girlfriend.

In an interview with journalist Andrew Morton, Princess Diana said that the happiest times in her marriage to Prince Charles were the years before the birth of Prince Harry. Because by 1985, the Prince of Wales had a full-blown affair with Camilla.

Meanwhile, Robert Lacey, the author of the biography Battle of Brother, also confirmed that Prince Charles was pressured into marrying Lady Diana because of Prince Philip. The Duke of Edinburgh expressed to his son that he needs to get down on one knee and propose or walk away from Diana "immediately" to protect her good name.

Prince Charles and Princess Diana separated in 1992 and then divorced in 1996. The following year, the Princess of Wales succumbed to an accident in Paris. Twelve years later, Charles married Camilla, who became the Duchess of Cornwall.