Princess Diana humiliated Prince Charles during a state banquet.

The Prince and Princess of Wales had a rocky relationship. Shortly after welcoming their two sons Prince William and Prince Harry, their marriage ended in divorce.

According to royal correspondent Ross Benson in his book “Charles: The Untold Story,” Princess Diana was not expected to attend the state banquet for President Mario Soares of Portugal at Buckingham Palace in 1993.

In 1992, Prince Charles and Princess Diana announced their separation. Following their split, the Princess of Wales was banned from every royal occasion and only Queen Elizabeth II could enforce an order to allow her presence back at an official royal event.

One time, Princess Diana suddenly phoned the Queen and informed her that she would attend the state banquet. The monarch couldn’t reportedly bring herself to enforce the ban because she was “frightened.”

“The Queen was frightened of the influence that Diana exerted over her sons, William and Harry,” Benson wrote.

“And most of all frightened over the future which she senses belongs to Diana. That is why the Queen shied away from telling Diana that she would be unwelcome at the State banquet.”

Since Queen Elizabeth II wasn’t able to stop her daughter-in-law, Princess Diana hijacked the royal event. The People’s Princess reportedly walked into the official ceremony at the palace and stood beside the Prince of Wales, who was described by the author as the “husband who detested her.”

“She had outshone him, outmanoeuvred him and finally humiliated him,” Benson continued.

It was not the only way Princess Diana made her vengeance to Prince Charles following their failed marriage which she blamed to his affair with Camilla Parker Bowles. The Princess of Wales publicly exposed the heir apparent in her infamous Panorama interview when she said, “there were three of us in this marriage, so it was a bit crowded.”

Royal biographer Penny Junor said that Princess Diana had a “superb performance” in the interview that it was worthy of an Oscar. No one expected her shocking revelations. She reportedly told her private secretary about it but didn’t give specific details. Princess Diana just said that “it’s terribly moving.”

Prince Charles and Princess Diana
Prince Charles and Princess Diana are pictured attending a centenary service for the Royal College Of Music on Feb. 28, 1982 at Westminster Abbey, London. Fox Photos/Hulton Archive/Getty Images