Voir sur FrenchStream. Most people think that World War II started on September 1st, 1939, when the Germans invaded Poland, and then spread to Asia on September 7th 1941, after the Japanese attacked Pearl Harbor. However, World War II actually started ten years earlier, when Manchuria was invaded by a now-forgotten Japanese general: Kanji Ishiwara. This is the little known truth about the most famous war in history.