context: The Winter War, November 30, 1939 - March 13, 1940, was a war between Finland and the Soviet Union. The Soviet Union began the Winter War by attacking without declaring war, and ended 105 days later in the Moscow Peace Treaty. The League condemned the attack and resigned from the Soviet Union on December 14, 1939.
question: How did the Winter War begin?
answers.text: The Soviet Union began the Winter War by attacking without declaring war