In a recent Press utterance we find an appeal to prohibit chemical warfare and to "trust the general sentiment of the civilised world to say that the lesson has been learnt in that sense." "There is the League of Nations to furnish that sentiment with a mouthpiece and a sanction." We agree, but to stop there is dangerous, the most important thing which it must furnish is a mechanism of control, a check, or guarantee. This question is one of the most important which confronts us for world peace. It merits the most careful consideration. Even responsible and relevant officials who admit that their League must do more than issue edicts, that their mechanism must function, are ignoring the specific technical aspect of the war methods whose use we wish to limit. This matter will receive later attention. The following pages, therefore, are an attempt to represent the salient points in the development of chemical warfare, its causes, results, and future. Such an attempt cannot limit itself to merely British developments, and this is not a final detailed memoir of British chemical warfare. Further, in considering the future, we examine another aspect of chemical warfare. Facts lead us to believe that it was purely the most open and obvious activity in a whole campaign of chemical aggression which had effective unity of conception and direction long before the war started. Need for a Balanced View of Chemical Warfare.--The facts of chemical warfare have probably been less ventilated than those of any other important war development. Yet no subject has aroused more general and intense feeling. Tanks, aircraft, the different campaigns, enemy memoirs, and a variety of war subjects, have received a considerable measure of publicity, some more than full measure. Grave questions are pending in which the chemical aspect of national defence is a prominent factor. However willing the individual concerned, he cannot make a sound judgment on the brief technical or popular garbled versions which have appeared. One searches in vain for balanced and detailed statements on the question. This may be due in no way to lack of intention, but to lack of opportunity. Therefore, no excuse is needed for this contribution, but rather an apology for the obscurity which has so far surrounded the subject. What is the cause of this emotional or almost hysterical background from which a clear definition of the matter is only now beginning to emerge? Circumstances are to blame; the first open act of chemical warfare decided the matter.