“Wasn’t it 1931?”
You are right. Japan started firing on Manchuria in Sept. 1931. However, the war really didn’t begin in earnest until the China incident of 1937. Also, I disprove the notion that China would be conquered by Japan if US would’ve entered the war. You have to remember, that even by Dec. 1941, China still wasn’t conquered yet. Also, the Republic and the Maoist joined forces in 1937 against the common enemy, Japan. Though China was still very 3rd world, it did receive valuable war shipments from USA. China’s estimated 400 million people seemed to offer the Allies a great military asset in terms of inexhaustible manpower.