The major theatres of operations were the Liaodong Peninsula and Mukden in Southern Manchuria and the seas around Korea , Japan and the Yellow Sea .

The Mukden Incident , or Manchurian Incident , was an event staged by Japanese military personnel as a pretext for the Japanese invasion in 1931 of northeastern China , known as Manchuria .

On 18 September 1931 , Lt. Suemori Kawamoto of the Independent Garrison Unit ( 独立守備隊 ) detonated Terrorism a small quantity of dynamite close to a railway line owned by Japan 's South Manchuria Railway near Mukden ( now Shenyang ) .

With the building of the South Manchuria Railway , Mukden ( now known as Shenyang ) became Becoming a Russian stronghold , which occupied Control it after the Boxer Rebellion .

In 1931 , the Mukden Incident helped Assistance spark the Japanese invasion Attack of Manchuria .

The Japanese invasion of Manchuria began Process_start on 18 September 1931 , when the Kwantung Army of the Empire of Japan invaded Attack Manchuria immediately following the Mukden Incident .