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The future King Edward VIII with the Duke of York (the future King George VI), Prince Henry, Duke of Gloucester and Prince George, Duke of Kent—whose mysterious death happened 84 years ago today.

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On 25 August 1942, Prince George, Duke of Kent, son of King George V and Queen Mary, died in a military air crash at the age of 39. It brought a tragically early end to the life of a beloved son, brother, father, and husband, marking the first time in several centuries that a member of the royal family had died during active service.

It was a foggy day above the mountains of Scotland that the Royal Air Force plane went down, with the fragments of the aircraft quickly destroyed and the lone survivor silenced by the Official Secrets Act.

What happened above Caithness that day remains a mystery. The report, which was drafted to solve the case of the dead Duke of Kent, went missing—his legacy lost to history. But who was the charismatic king’s brother, whose libertine love life, glamorous marriage to Princess Marina of Greece, and dedication to the RAF endeared him to the British public?

On December 20, 1902, George was born at York Cottage, Sandringham, the fourth son of the then Prince and Princess of Wales. His father, George, was the only surviving son of King Edward VII and Queen Alexandra; his mother, Mary, was the daughter of the Duke and Duchess of Teck. Prince George was one of six siblings—his brother, Prince John, died at just 13 years old.

At the time of his birth, Prince George was fifth in line to the throne behind his father and three older brothers: Edward (the future King Edward VIII and Duke of Kent), Albert (King George VI, father of Queen Elizabeth II), and Henry, Duke of Gloucester. George was baptised at Windsor Castle in January 1903, and his godparents reflect the close bonds between the British royals and their European cousins: Prince Valdemar of Denmark, Prince Louis of Battenberg, Empress Dowager Maria Feodorovna, and Princess Christian of Schleswig-Holstein.