The Mukden Incident occurred on September 18, 1931, when a small explosion was staged by the Japanese military near the city of Mukden in Manchuria. This event was used as a pretext for Japan to invade and occupy the region, claiming it was necessary for their security. The incident marked the beginning of a broader conflict in Manchuria and led to the establishment of the puppet state of Manchukuo. The incident is significant as it exemplified Japan's aggressive expansionist policies during the early 20th century. It also highlighted the failure of the League of Nations to address international aggression, as Japan withdrew from the organization after being criticized for its actions in Manchuria. The Mukden Incident set the stage for further military conflicts in Asia leading up to World War II.