When World War II began, he was appointed the French Official Observer attached to the British General Headquarters. In this capacity he accompanied the British Army to Belgium. He knew personally the main politicians in the French Government, and on 10 June 1940 he was sent on a mission to London. The Armistice ended that mission. Maurois was demobilised and travelled from England to Canada. He wrote of these experiences in his book, Tragedy in France.Maurois, 1940, Foreword
