Political map of East Asia and the Western Pacific 23 August 1937 (Battle of Shanghai): For the month following the Marco Polo Bridge Incident, it appeared fighting between Japan and China would be restricted to the north. Then, in August, a Japanese officer was shot by Chinese troops in Shanghai (Oyama Incident) and the war (Second Sino-Japanese War) suddenly expanded. Peace negotiations collapsed as almost a million Chinese and Japanese troops poured into Shanghai and a battle which would rage for over three months (Battle of Shanghai).