Prince Philip, Duke of Edinburgh Athens for a month in mid-1939. At the behest of the Greek king, George II, he returned to Britain in September to resume training for the Royal Navy. He graduated from Dartmouth the next year as the best cadet in his course. During the Second World War, he continued to serve in the British forces, while two of his brothers-in-law, Prince Christoph of Hesse and Berthold, Margrave of Baden, fought on the opposing German side. Philip was appointed as a midshipman in January 1940. He spent four months on the battleship HMS "Ramillies", protecting convoys of the Australian Expeditionary Force
Prince Christoph of Hesse the sister of the future Prince Philip, Duke of Edinburgh. They had five children: Prince Christoph of Hesse Christoph Ernst August of Hesse (Frankfurt, 14 May 1901 – Apennine Mountains near Forlì, 7 October 1943) was the fifth son of Prince Frederick Charles of Hesse and Princess Margaret of Prussia. He was a German SS officer killed in a plane crash during World War II. He was a brother-in-law of Prince Philip, the consort of Queen Elizabeth II. Born in Frankfurt, Prince Christoph was a great-grandson of Queen Victoria and Prince Albert of Saxe-Coburg and Gotha through their eldest daughter