In 1937, at age eleven, Elizabeth's life took a definitive turn when her uncle abdicated, and her father was crowned King George VI. Elizabeth was the Heir Presumptive to the Throne. Elizabeth still enjoyed occasional pranks, but she was also maturing into her position as the future head of the monarchy with her move to Buckingham Palace. A descendant of the Heir Presumibles is required to study all there is to know about state matters, so she took it upon herself to do so. In addition, she studied European history as a part of her education at Eton. Margaret and Elizabeth were both educated in constitutional history and broadened their knowledge of European history. When Hitler invaded Poland in 1939, their studies were curtailed. During the war, Elizabeth and Margaret were suggested to be evacuated to Canada. The Princesses were ordered not to leave because the King would not leave, and their mother would not leave either. Thus, they stayed first at Balmoral, then Sandringham, and finally Windsor.