British royal family patriarch Prince Philip
, 96, has lived a long and full life. He married Queen Elizabeth in 1947 and has since welcomed four children, eight grandchildren, and five great-grandchildren. But Philip's older sister, Princess Cecilie of Greece and Denmark's life was tragically cut short on a foggy day in Belgium in 1937. Philip, Cecilie, and their three siblings are the children of Prince Andrew of Greece and Denmark (son of King George I of Greece) and Prince Alice of Battenberg (great-granddaughter of Queen Victoria of England). The family was exiled from Greece in 1922 and settled in Paris. And in 1931, Cecilie married Georg Donatus, Hereditary Grand Duke of Hesse — or "Don" for short — with whom she would raise three children. Actors portraying a young Philip and Cecilie on The Crown
. (Photo Credit: R/R) Then, tragedy struck. On Nov. 16, 1937, Don and Cecilie departed Frankfurt, Germany, en route to London for the wedding of Don's younger brother Louis.