The 400 Million

The 400 Million, also known as China in 1938, was a 1939 black-and-white documentary film by Dutch filmmaker Joris Ivens about the Second Sino-Japanese War, part of the East Asian theater of World War II. The filmmaker moved between the Republican, Communist, and guerrilla forces of the Chinese resistance to Japanese invasion. Their dialogue in Mandarin is accompanied by English translations read by American actors.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.