What is biological warfare ?
The use of biological poisons or infectious agents , such as bacteria, viruses, and fungus, with the intention of killing or incapacitating people , animals, or plants as an act of war is known as biological warfare, also referred to as germ warfare.
For Instance: Spain used the biological weapon i.e smallpox to conquer America. Smallpox is an infectious fast spreading disease. Smallpox turned out to be a fatal killer illness. Whole communities were killed and destroyed, paving the way for Spain to Conquest the US territory.