The Manchurian Crisis of 1931 posed a major challenge to the League of Nations and the Far East became the focus for the UK League of Nations Union and other groups and activists for peace. The crisis began on 18 September 1931 when an explosion occurred close to the Japanese-owned railway line near Mukden in China. It soon became obvious that the explosion was engineered by the Japanese to enable them to invade the province of Manchuria, an area rich in raw materials much needed by the island nation.
China appealed to the League of Nations. In accordance with the Covenant of the League the threats of moral condemnation, economic sanctions or military action were discussed. However, the lack of support from the United States, which was not a member of the League, meant that any of these would prove ineffective. In the event, and as a face-saving exercise for the League, a Commission was set up under Lord Lytton to report on the incident. In 1932 the Lytton Report found Japan to be the aggressor. Japan was condemned, leading to diplomatic isolation. Her response in March 1933 was to walk out of the League of Nations. Following her exit from the League Japan began a programme of expansion in the Far East.