What is Germ Warfare?

Germ warfare is, these days, more typically known as
biological warfare.  It is the use of biological agents to kill or incapacitate your
enemy in war or to destroy the enemy's resources.

For
example, during World War II, the Japanese experimented with trying to spread bubonic
plague by dropping infected fleas from airplanes.  This did not really come to anything,
but it would have been germ warfare -- trying to kill enemies by making them
ill.

Another example would be if someone introduced a
really bad disease of (for example) corn to the American Midwest.  If an enemy did this,
they might (if they were successful) really hurt the American
economy.