The Marco Polo Bridge Incident was a conflict between the Republic of China's National Revolutionary Army and the Imperial Japanese Army. It is widely considered to have been the start of the Second Sino-Japanese War (1937–1945).
This led to the Chinese army's successful defense of Marco Polo Bridge, but China lost a lot. It is recorded that, with the exception of the four Chinese troops, all other troops died.
The Japanese drive to become a great power required the domination of China. They defeated the Chinese prior in the First Sino-Japanese War in the 1890s and took away Korea. In 1931 they took over Manchuria and expanded the south.After Manchuria was taken over, Japan set up many industries to take advantage of the country's resources which had rich amounts of coal and other minerals.
A key moment came in 1937. Under agreements going back to the beginning of the century countries with legations in China had the right to keep troops there in modest numbers for protection. Small numbers of both Japanese and Chinese soldiers were stationed near what in the West was called the Marco Polo Bridge, because the explorer had seen and described its predecessor, near the town of Wanping outside Beijing.
What happened that July night is not entirely clear, but the Japanese were carrying out training exercises without giving the customary notice and a few shots were exchanged between them and the startled Chinese troops. The Japanese discovered that one of their soldiers was missing, thought the Chinese might have captured him and demanded to be allowed to search Wanping for him. The Chinese said they would do the searching themselves, with one Japanese officer accompanying them. Japanese infantry then tried to force their way into Wanping, but were driven back. Both sides sent more troops to the area and early in the morning of July 8 Japanese infantry and armoured vehicles attacked the bridge and took it, but were driven off again.
Attempts were made to settle things, but the incident gave Japanese hawks the excuse to mount a full-scale invasion of China. Hundreds of thousands of troops were sent in. Beijing and Shanghai fell in 1937, as did Nanjing, where Chiang Kai-Shek had established his Kuomintang capital. (According to one theory the whole thing was stage-managed by the Chinese Communists to embroil the Kuomintang in a war with the Japanese.)
The fighting was accompanied by vicious atrocities. At least around 100,000 Chinese had been slaughtered in the Rape of Nanjing, including thousands of Chinese women raped before being murdered. Victims were buried or burned alive, dismembered alive or drowned. By the end of 1938 much of northern and eastern China had been overrun, including the eastern seaboard. The conflict continued until it blended into the Second World War.