Second Sino-Japanese War
In 1931, the Imperial Japanese Army began to occupy China, starting in the northeast (Manchuria), where they created a puppet state called Manchukuo. In 1937, they occupied Beiping (now called Beijing), and then Nanjing.  For six weeks in Nanjing, the army committed the Nanjing Massacre.  During this massacre, Japanese soldiers killed between 40,000 and 300,000 Chinese people, and raped at least 20,000 women and girls.