chemical warfare, n.All

Adolf Hitler wore his mustache in that fashion after shaving it to fit his gas mask in World War I

Shaving really only became popular after World War I when troops returned home having been clean-shaven so that gas masks could securely fit on their face.

Chemical warfare is no worse than conventional warfare. It is in no way worse to make a man's eyes water with gas than to fill his bodies with fragments of a bursting shell.

Chemical warfare is psychiatry’s answer to the battlefield of the mind.