Princess Diana didn’t have any idea that her dad, John, 8th Earl Spencer, was a World Ward II hero.

During his interview on “Today,” the Princess of Wales’ only brother, Charles Spencer, talked about his late dad. He said that he only found out recently that his father was a wartime hero after receiving a letter from someone he didn’t know personally.

In the letter, it was revealed that John led a British Army unit to liberate two French towns.

"My family and I really didn’t know anything about my father’s war story beyond the bare minimum, so I always had this question mark as to what he had done. I got this letter out of the blue a few years ago. Totally surprised – ‘Do you know who a Lt. Althorp was? Because we have records, he was involved in our liberation…’ And I wrote back and said ‘Yes, Lt. Althorp would have been my father,’” he said.

Since Charles didn’t have any idea about his dad’s past, it is highly likely that Princess Diana didn’t also know that his dad served in World War II. The late royal didn’t have a close relationship with her parents. In fact, growing up, Princess Diana blamed herself for her parents’ divorce.

According to royal experts, Princess Diana’s parents always wanted to have a baby boy, and they did. But shortly after John was born, he passed away. Princess Diana was born after her older brother, and her parents hoped that she would always be a boy.

Growing up, Princess Diana thought that this was one of the reasons why her parents split. But during an interview, Frances Shand Kydd denied the allegations. She said that she and her entire family were delighted following Princess Diana’s birth, and they didn’t have any problems with her being a girl.

Princess Diana passed away on Aug. 31, 1997, following a fatal car crash in Paris.

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Britain's Princess of Wales arrives at her London health club. Johnny Eggitt/AFP/Getty Images)