Ningbo plague attack

The Ningbo plague 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 attack launched by Japan in October 1940 against the Kaiming Street area of Ningbo, Zhejiang, China, using fleas infested with plague (Yersinia pestis). A joint operation of the Imperial Japanese Army's Unit 731 and Unit Ei 1644, the attack was carried out by military planes taking off from Jianqiao Airport in Hangzhou, 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 warfare 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 an isolation wall 4.3-metre (14 ft) high 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 burned area was still referred to as the "plague field". According to the doctoral thesis of Junichi Kaneko, a military doctor of Unit 731, on October 27, 1940, Unit 731 spread 2 kilograms (4.4 pounds) of plague bacteria over Ningbo using aircraft, resulting in a total of 1,554 deaths from the first- and second-round infections.