The Kaimingjie germ weapon attack (simplified Chinese: 开明街鼠疫灾难; traditional Chinese: 開明街鼠疫災難; lit. 'Kaiming Street Plague Disaster') was a secret biological warfare launched by Japan in October 1940 against the Kaiming Street area of Ningbo, Zhejiang, China. A joint operation of the Imperial Japanese Army's Unit 731 and Unit 1644, this attack was operated by military planes taking off from Jianqiao Airport in Hangzhou,: 89 which airdropped wheat, corn, cotton scraps, and sand infected with plague fleas to target locations. From September 1940, Ningbo, Quzhou, and other places were subjected to various forms of biological warfares until the end of October 1940, when the attacks triggered a plague epidemic in Ningbo.
After the outbreak of the plague, the city authorities in Ningbo built a 4.3-meter-high isolation wall around the epidemic area, segregating patients and suspected cases, and eventually burned down the Kaiming Street area to eradicate the disease. Until the 1960s, this...