Second Sino-Japanese War
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan from July 7, 1937, to September 2, 1945. It began with the Marco Polo Bridge Incident in 1937 in which a dispute between Japanese and Chinese troops escalated into a battle.
During the Marco Polo Bridge Incident Japanese military demanded permission to enter the Chinese city of Wanping to search for a missing soldier. The Chinese refused.