<human>:  Why did the Japanese lose the battle of Nanjing?
<bot>: The Japanese were outnumbered and outgunned. They were also ill prepared for the war in China. The Japanese had not anticipated the speed with which the Chinese forces could mobilize and move, and they were unprepared for the large scale use of modern weapons, such as artillery and aircraft. The Japanese forces were also poorly trained and ill equipped, and many of them lacked the discipline to fight effectively.