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Note the sharp curtain which is formed, behind which the infantry advance.

INTRODUCTION

No one who has the welfare of the country at heart can fail to share Major Lefebure's anxiety that a clear, accurate, and unbiased account of chemical warfare should be presented to the public, so that the many erroneous ideas now prevalent in regard to poison gas and its uses may be dispelled.

The whole subject of chemical warfare is at present sub judice, and there is great danger that the future safety of this country may be jeopardised by the almost universal ignorance of the peculiarities and potentialities of this class of warfare. Recent publications in the Press have shown a tendency to deal with the subject on purely sentimental grounds, and attempts have been made to declare this form of warfare illegitimate without full and careful consideration of all the facts and their significance for the future.

Major Lefebure has therefore attempted in his book to make it quite clear that no convention, guarantee, or disarmament safeguard will prevent an unscrupulous enemy from employing poison gas, especially if that enemy has discovered some new powerful agent, or possesses, as Germany does in her well-organised and strong chemical industry, a ready means for producing such chemicals in bulk at practically a moment's notice; further, that the safety of this country makes it imperative that the study and investigation of the subject should be continued and that our chemical and dye industry should be developed, so that when an emergency arises we may have the necessary facilities for supply ready to hand.

It is not for me to express any opinion here either as to the desirability of using gas as a weapon or as to the possibility of preventing an enemy from using it. But I am convinced that a decision come to without full knowledge of the facts may involve grave danger and heavy preventable loss of life. I am further convinced that Major Lefebure, by his special knowledge and long experience as chemical liaison officer during the war, is well qualified to speak, and that his opinion is entitled to full consideration. For these reasons I think that his book will do a much needed public service. I wish it every success, and the greatest possible number of readers. HENRY WILSON, F.M.

CHAPTER 1

EXPLANATORY

The Riddle of the Rhine.—The Great War challenged our very existence. But with the tension released, and the Allies victorious, the check to the German menace appears crushing and complete. Few realise that one formidable challenge has not been answered. Silently menacing, the chemical threat remains unrecognised. How, asks the reader, can this be? Are we not aware of the poison gas campaign? Indeed, we have not yet grasped the simple technical facts of the case, and these are merely the outward signs of a deep-rooted menace whose nature, activities, and potentialities are doubly important because so utterly unsuspected by those whom they most threaten.