Mustard gas is a very different thing. It was never used to force a decision by breaking the enemy’s lines, but to cause him casualties and deny him the use of ground. For, after a given area has been well sprayed with dichlorethyl sulphide from bursting shells for some time, it is death to occupy it without a mask, and the vapour may blister the skin, while anyone touching the ground will be certain of a very serious blister. Someone placed a drop of the liquid on the chair of the director of the British chemical warfare department. He ate his meals off the mantelpiece for a month. The most interesting thing, however, about mustard gas is that, though it caused 150,000 casualties in the British Army alone, less than 4,000 of these (or 1 in 40) died, while only about 700 (or 1 in every 200) became permanently unfit. Yet the Washington Conference has solemnly agreed that the signatory powers are not to use this substance against one another, though, of course, they will use such humane weapons as bayonets, shells, and incendiary bombs. It is worth while attempting to analyse the reasons for this rather curious decision. First, perhaps, we must put the complete and shameful ignorance of most of the politicians and many of the soldiers who took part in the Conference. Their ideas of gas warfare were apparently drawn from the descriptions of the great German cloud-gas attacks of 1915, which killed at least 1 in 4 of their casualties, and were written up on a large scale for recruiting and political purposes. But it is the business of politicians and soldiers, conceivably even of journalists, to know the truth about such matters before coming to decisions, or even impelling others to come to decisions about them. To this ignorance, however, there was joined one of the most hideous forms of sentimentalism which has ever supported evil upon earth――the attachment of the professional soldier to cruel and obsolete killing machines. I would remind you of the conduct of the Chevalier Bayard, whom his contemporary soldiers described as _sans peur et sans reproche_. To captured knights, and even bowmen, he was the soul of courtesy, but musketeers or other users of gunpowder who fell into his hands were invariably put to death. It is worth remembering that, until the invention of gunpowder, fighting had for many centuries been remarkably safe for everyone who could afford a good suit of armour, while the abominable arquebus and its descendants have saved the remnants of Christendom from the Turks, Mongols, and other paynims who had by Bayard’s time successfully overwhelmed one half of its original extent.