In 1931, the Japanese imperial army staged the September 18 Incident – a false flag operation designed to justify its invasion of China. Eleven months later, Shiro Ishii arrived in Northeast China, where he set up the Kwantung Army's Epidemic Prevention and Water Purification Department, which would later become known simply as Unit 731. In the guise of epidemic prevention and water purification work, it conducted experiments on living human beings as part of a program to develop biological weapons. A museum in Harbin contains evidence of the horrific crimes Unit 731 committed during World War II. These atrocities were crimes against humanity and an outrage that trampled on human conscience. Yet, many Westerners remain unaware of this dark chapter in history.