Japanese marines at Guangdong in the Battle of Wuhan
Most historians place the beginning of the Second Sino-Japanese War on July 7, 1937 at the Marco Polo Bridge Incident, when a crucial access point to Beijing was assaulted by the Japanese. Some Chinese historians, however place the starting point at the Mukden Incident of September 18, 1931. Following the Mukden Incident, the Japanese Kwantung Army occupied Manchuria and established the puppet state of Manchukuo on February 18, 1932. Japan tried forcing the Chinese government to recognize the independence of Manchukuo. However, when the League of Nations determined that Manchukuo was a product of Japanese aggression, Japan withdrew from the League.
Following the Marco Polo Bridge Incident in 1937, the Japanese occupied Shanghai, Nanjing and Southern Shanxi in campaigns involving approximately 350,000 Japanese soldiers, and considerably more Chinese soldiers. Historians estimate up to 300,000 people perished in the Nanking Massacre, after the fall of Nanjing on December 13, 1937, while some Japanese historians denied the existence of a massacre at all. Throughout the next few years, the Japanese air force launched air bombing raids on nearly every city in China, leaving millions homeless.
The Marco Polo Bridge Incident not only marked the beginning of an open, undeclared, war between China and Japan, but also hastened the formation of the Second United Front between the Kuomintang (KMT)and the Chinese Communist Party (CCP). The cooperation took place with salutary effects for the beleaguered CCP. The high point of the cooperation came in 1938 during the Battle of Wuhan . However, the distrust between the two antagonists was scarcely veiled. The uneasy alliance began to break down by late 1938, despite Japan’s steady territorial gains in northern China, the coastal regions, and the rich Yangtze River Valley in central China. After 1940, open conflict between the Nationalists and Communists became more frequent in the areas outside Japanese control, culminating in the New Fourth Army Incident. The Communists expanded their influence wherever opportunities were presented, through mass organizations, administrative reforms, land and tax reform measures favoring peasants, while the Nationalists attempted to neutralize the spread of Communist influence and fight the Japanese at the same time.
The Japanese had neither the intention nor the capability to directly administer China. Their goal was to create friendly puppet governments favorable to Japanese interests. However, the atrocities committed by the Japanese army made the governments that were set up very unpopular. In addition, the Japanese refused to negotiate with the Kuomintang or the Communist Party of China, which fueled further anti-Japanese sentiments. The Japanese also forced the Chinese people living under their control to change their money into military banknotes, which the current Japanese government still refuses to exchange even today