 In 1936 , her husband unexpectedly became King when his brother , Edward VIII , abdicated in order to marry the American divorcée Wallis Simpson . Elizabeth became Queen . She accompanied her husband on diplomatic tours to France and North America before the start of World War II . During the war , her seemingly indomitable spirit provided moral support to the British public . In recognition of her role as an asset to British interests , Adolf Hitler described her as " the most dangerous woman in Europe " . After the war , her husband 's health deteriorated and she was widowed at the age of 51 . Her elder daughter , aged 25 , became the new Queen . 
