In July 1937 Japan invaded China. In the summer and autumn of 1937 CHIANG Kai Shek tried to defend Shanghai, but he finally withdrew and retreated to Nankin, and then along the Yangzi river towards Wuhan (an industrial area composed of 3 cities, the most important of which was Hankou). It was there that in 1938 he opposed once again the Japanese forces. Between July and September 1938, the city of Hankow was heavily bombed by Japan.