Most people in the civilised world condemn the use of biochemical weapons, such as in the recent alleged gassing to death of more than 1,000 citizens in Syria. Weapons that use chemicals to poison the body’s biological functions and cause large numbers of fatalities are not a modern invention. The first recorded use of such methods of warfare in China was during the Western and Eastern Han dynasties (206BC-AD220).
China and the Xiongnu nation, to its north and west, were then fighting on and off in a war that lasted several centuries. During the reign of Emperor Wu (141-87BC), China’s military power was at a peak and its troops made deep inroads into Xiongnu territory. The battered Xiongnu had to resort to “magic”. When they received intelligence that Chinese troops were attacking along a certain route, their shamans would place a hex on several cows and goats. Then they either buried the animals’ carcasses along the way or dumped them in water sources. When the Chinese invaders drank the water, entire legions suddenly fell sick and died, thus giving the Xiongnu a brief respite.
It’s not known how but it’s almost certain the shamans caused the livestock to be infected by a contagious virus that spread to humans and resulted in widespread death by biochemical means.