As far back as in the Ancient Chinese Empire, the plague has been used as a weapon in warfare. The Huns, the Mongols, and the Turks are just a few of the many groups said to have used the plague as weaponry--whether by contaminating water supplies with the carcasses of infected animals or even catapulting the bodies of plague victims into enemy cities. (However, given the fact that the bubonic plague is only transmitted to humans through animals, these warfare techniques may not have been very effectual). More effectively perhaps, in World War II Japan released large numbers of infected fleas in designated enemy territories as well as intentionally infected many of their prisoners of war. Since World War II, the United States is said to have developed biological weapons involving the pneumonic plague.
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