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.
Background
Japanese biological warfare plan In June 1925, Japan signed the Geneva Protocol, which committed Japan to refrain from using biological and chemical weapons in warfare. The development of Japan's biological weapons was highly secretive and led by Shiro Ishii. He planned and raised funds for Japan's biological weapons program. In 1939, the Imperial Japanese Army established Unit Ei 1644 in Nanjing to conduct research on biological and chemical weapons. Units Ei 1644 and 731 studied the effects of various chemicals and pathogens that could be used as biological weapons on soldiers and civilians and developed weapons to further expand the Japanese Empire's territory in Asia. After the failure of the rapid decisive victory plan in the war against China, the Japanese military began using bacteriological weapons. In the summer of 1939, during the Battle of Khalkhin Gol, the Imperial Japanese Army used biological and chemical weapons against Soviet and Mongolian troops. On June 13, large quantities of white powder were airdropped in the vicinity of Lihai, Shaoxing. On June 15, chemical tests conducted by the local river police did not reveal any abnormalities, but subsequent bacterial culture tests revealed turbidity in one test tube and cotton-like floating substances in another, with pathogens such as tetanus and diphtheria observed under a microscope. Within days after the airdrop, the weather in Shaoxing was clear and sunny, with abundant sunlight, which was not conducive to bacterial growth, so no epidemic outbreak occurred. This is the earliest recorded instance of the Japanese military's bacteriological weapon attack in Zhejiang.
Strategic location of Ningbo Before 1937, Zhejiang cities such as Ningbo, Jinhua, and Quzhou in Zhejiang did not experience a plague epidemic. However, people may have been aware of the plague near Ningbo in Shanghai in 1910. The incubation period of the plague is 2 to 8 days. At the time of the outbreak, sulfa drugs, streptomycin, and other antibiotics had not yet been invented, so residents of Ningbo could not have access to antibiotics and were primarily treated with serum. Without treatment, the mortality rate of the plague was almost 100%, and there was not enough serum supply prepared in advance. After the outbreak of the Second Sino-Japanese War in 1937, Ningbo became one of the important seaports for China to obtain international aid supplies, with a daily throughput of over 10,000 tons of goods. As a port city with a population of 260,000, Ningbo had numerous streets, dense housing, crowded residents, relatively poor sanitary conditions, high population mobility, and frequent goods entering and leaving, making it easy for the plague to spread and proliferate through people and goods transmission. Kaiming Street is a north-south urban main road in Ningbo and is the main commercial centre of the old city. Since the first Japanese air raid on Lishe Airport on August 16, 1937, the Japanese military had directly attacked Ningbo at least 7 times. On 17 July 1940, the Japanese military first invaded Zhenhai, but were driven out by the Chinese army five days later on the 22nd. The Japanese military again bombed Ningbo on 5 and 10 September of the same year.
Operation
Decision-making
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