The
Winter War (, , ) was a military conflict between the
Soviet Union and
Finland in 1939–1940. It began with the Soviet invasion of Finland on 30 November 1939 (three months after the outbreak of
World War II), and ended with the
Moscow Peace Treaty on 13 March 1940. The
League of Nations deemed the attack illegal and expelled the Soviet Union from the League on 14 December 1939.