Nazi Germany's occupation of Czechoslovakia in March 1939 and its invasion of Poland in September 1939 (the latter invasion immediately drawing France and Britain into World War II) provoked the drive to explain the phenomenon of Nazi Germany. In 1940, Sebastian Haffner, a German émigré living in Britain, published Germany: Jekyll and Hyde, in which he argued it was Adolf Hitler alone, by the force of his peculiar personality, who had brought about Nazi Germany.