"s were recognized for their potential impact on people and armies as early as 600 BC … The crude use of filth and cadavers, animal carcasses, and had devastating effects and weakened the enemy … Polluting wells and other sources of water of the opposing army was a common strategy that continued to be used through the many European wars, during the American Civil War, and even into the 20th century. Military leaders in the Middle Ages recognized that victims of infectious diseases could become weapons themselves …"