Someone know the Second Sino-Japanese War?

The Second Sino-Japanese War (1937–1945) was a military conflict that was primarily waged  

between the Republic of China and the Empire of Japan. The war made up the Chinese theater  

of the wider Pacific Theater of the Second World War. The beginning of the war is  

conventionally dated to the Marco Polo Bridge Incident on 7 July 1937, when a dispute  

between Japanese and Chinese troops in Peking escalated into a full-scale invasion. This  

full-scale war between the Chinese and the Empire of Japan is often regarded as the  

beginning of World War II in Asia. In 2017 the Ministry of Education in the People's  

Republic of China decreed that the term "eight-year war" in all textbooks should be  

replaced by "fourteen-year war", with a revised starting date of 18 September 1931 provided  

by the Japanese invasion of Manchuria. According to historian Rana Mitter, historians in  

China are unhappy with the blanket revision, and (despite sustained tensions) the Republic  

of China did not consider itself to be continuously at war with Japan over these six  

years.[28] The Tanggu Truce of 1933 officially ended the earlier hostilities in Manchuria  

while the He-Umezu Agreement of 1935 acknowledged the Japanese demands to put an end to all  

anti-Japanese organizations in China.

Explanation:

4 copper and gold, the california gold rush is why im pretty sure.