The Nanjing Massacre was a massacre (an unjust killing of many people) that happened in Nanjing, China, in December of 1937 and January of 1938. It was part of the Second Sino-Japanese War, which was the part of World War II between China and Japan. At the time, Japan was trying to take over China and Nanjing was the Chinese capital. The Japanese Army reached Nanjing on 13 December 1937 and began killing thousands upon thousands of men and boys and raping thousands upon thousands of women and girls.