Japanese biological warfare practitioners got the same kind of immunity as German rocket scientists. Japanese experiments had killed perhaps as many as 10,000 Chinese, mostly conscripted civilians. One practitioner, Shiro Ishii, was the commander, and he got a free pass for himself and his outfit. By the time we learned that they had been only sadists amusing themselves, leaving nothing useful for scientists or weaponeers, it was too late. Monsters went free.
War is horrible enough with blades and munitions, which combatants wield with varying degrees of enthusiasm.
Chemical and biological weapons, however, inspire a kind of universal queasiness, which has not kept them from being used.
English blankets with smallpox traces felled Native Americans at long range. For millennia, animal and human corpses in wells and creeks have worked wonders. Munitions technology actually has reduced crude biological warfare. Conquerors need to drink, too.
“The Living Weapon” on “American Experience” obviously concentrates on biological weaponry, ways of disabling or killing enemies, including enemy civilian populations.