The Germans will perhaps not always be able to protect their retreats by the desert-like devastation of thirty or forty kilometres of country. Their weak point will be found some day or other, and on that day the cavalry will resume its importance. The difficulty in feeding and obtaining horses seems to have compelled the Germans to reduce their cavalry forces considerably. CHAPTER VII FORBIDDEN WEAPONS 1. Asphyxiating gases. 2. Tear-producing gases. 3. “Gaz-vésicant.” 4. Liquid fire. =1. Asphyxiating gases.= During the present war Germany has ransacked the arcana of science for the means of destroying her enemies. Those to which she resorted had been forbidden and condemned as belonging to barbarous ages by all the conventions to which she had been a party, and by all the agreements that she had signed. Asphyxiating gases were used for the first time against the British troops on the Yser. The corrosive vapours of chlorine are fatal to all who have been sufficiently exposed to them, and when first directed against an unprepared and unsuspecting enemy, their effects were terrible. Fortunately the use of these gases is possible only when the wind is favourable and the weather dry; and as the coincidence of these conditions is exceptional, especially in the north of France, the Allies had time to invent protective masks and distribute them to their troops. The models adopted can be slipped on easily and quickly even in the dark and are effective for several hours. Every soldier is provided with one. At the start, when gas-offensives were still in the experimental stage, the German attacks were limited to single discharges, which were more or less rapidly dissipated by the wind and were quite harmless to adversaries equipped with good masks. But shortly afterward, when their weapons were turned against them, and their trenches were “gassed” by the Allies, and the Germans discovered by experience that a mask causes great fatigue and even exhaustion if its use is greatly prolonged (since it interferes so much with the breathing), they altered their method of procedure and began to take advantage of favourable winds to launch successive waves of gas, in order to wear their enemies out by keeping them in their masks as long as possible. Next, as the approach of the whitish gas-cloud was easily visible and was always promptly signalled by the lookouts, the German scientists, in an effort to catch their adversaries unprepared, modified their original formulas and produced colourless gases, which are more difficult but by no means impossible to detect. =2. Tear-producing gases.= The next step was to find some means of nullifying as much as possible the protection of respiratory apparatus, so the _good_ Germans invented the tear-producing gases which, in spite of the special glasses that have been added to the masks, rapidly interfere with vision and place the victim _hors de combat_.