 Knowing a hasty retreat would discourage foreign aid, Chiang resolved to make a stand at Shanghai, using the best of his German-trained divisions to defend China's largest and most industrialized city from the Japanese.The battle lasted over three months, saw heavy casualties on both sides, and ended with a Chinese retreat towards Nanjing, but proved that China would not be easily defeated and showed its determination to the world.The battle became an enormous morale booster for the Chinese people, as it decisively refuted the Japanese boast that Japan could conquer Shanghai in three days and China in three months.