This kind of tactics was impossible during the Great War for a very simple reason. There was not enough mustard gas. The Germans used a quite surprisingly complicated process for its manufacture. When we decided to follow their example, one of our chemists (a Cambridge man, I am glad to say) hit on a vastly cheaper and speedier method of manufacture. Unfortunately, our first supplies only arrived in the field in September, 1918. There is reason to think that the knowledge that we were at last about to develop gas and smoke warfare on a large scale had a good deal to do with the acceptance by the Germans of the armistice conditions. The reason why we did not use mustard gas earlier is also simple and rather instructive. In 1915 a British chemist proposed to a General who was concerned with such questions that the British should use dichlorethyl sulphide. “Does it kill?” asked the General. “No,” he was told, “but it will disable enormous numbers of the enemy temporarily.” “That is no good to us,” said the man of blood; “we want something that will kill.” It is interesting to find how completely the ideas of this worthy soldier as to the object of war coincided with those of the average intelligent child of five years old. I may remind you that Clausewitz held the view that the object of war was to impose one’s will upon the enemy. This idea would, however, appear to have been too abstract, too complicated, or too humanitarian for the British military mind. At any rate, it had its fill of killing. It was not, therefore, until the Germans had demonstrated upon the persons of some tens of thousands of British soldiers (we had 14,000 casualties, though with only 400 deaths, during the first three weeks of the mustard gas war) that there was something to be said for a weapon that was not primarily designed to kill, that we began to use it. It seems, then, that mustard gas would enable an army to gain ground with far less killed on either side than the methods used in the late war, and would tend to establish a war of movement leading to a fairly rapid decision, as in the campaigns of the past. It would not much upset the present balance of power, Germany’s chemical industry being counterpoised by French negro troops. Indians may be expected to be nearly as immune as negroes.