WW2 is notable for not seeing widespread deployment of chemical weapons. Hitler had been subject to gas attacks as a foot soldier in WW1 and forbade the use of chemical weapons as inhumane.
Per https://en.wikipedia.org/wiki/History_of_chemical_warfare#Wo... this (a) overlooks the widespread use of chemical weapons in the Pacific theater, and (b) ascribes the non-use by Germany to humanitarian reasons, which is largely speculative. Actual quotes from officers discuss far more practical reasons: Germany feared chemical retaliation, and the horses relied upon for logistics could not be outfitted with sufficiently performant gas masks.
Entirely untrue in the Pacific theatre, with the Japanese doing human experiments both with germ and chemical agents. The largest scale use I remember was where they released infected rats (forget where) in a certain Chinese city to cause a plague.
