20. Are the arrangements, in case of gas attack, complete and known to all ranks? 21. Are the orders as to wearing equipment carried out? 22. Are my men using wood from the defences as firewood? 23. Are my men drinking water from any but authorized sources? 24. _I am here for two purposes: To hold this line under all circumstances, and I do as much damage as possible to the enemy? Am I doing all I can to make this line as strong as possible? Am I as_ OFFENSIVE _as I might be with organized snipers, sniperscopes, rifle grenades, catapults, etc., and patrols?_ Defensive Measure Against Gas Attacks. I. Introduction. A. General Considerations: In the absence of suitable means of protection the poison gases used in war are extremely deadly and the breathing of only very small quantities of them may cause death or serious injury. This being the case, it is essential that not the slightest time should be lost in putting on the anti-gas device on the gas alarm being given. It cannot be too strongly insisted on that the measures to meet hostile gas attacks afford _perfect protection_, and if they are carried out properly no one will suffer from gas poisoning. The whole basis of protecting troops against gas lies (a) in keeping the appliances in perfect working order; (b) in learning to adjust them rapidly under all conditions, and (c) in ensuring that every man is given immediate warning. These results can only be attained: (1) By frequent and thorough inspection of all protective appliances. (2) By thorough instruction and training in their use. (3) By every man understanding and complying with all standing orders on the subject of defense against gas. If these are effectually carried out, there is nothing to fear from hostile gas attacks. Officers must impress this on their men, as an important object of all anti-gas instruction should be to inspire complete confidence in the efficacy of the methods which are adopted. B. Nature of Gas Attacks: (1) GAS CLOUDS: This method of making a gas attack is entirely dependent on the direction of the wind. The gas is carried up to the trenches compressed in steel cylinders. These are dug in at the bottom of the trench and connected with pipes leading out over the parapet. When the valves of the cylinders are opened, the gas escapes with a hissing sound, which, on a still night, can frequently be heard at a considerable distance. It mixes with the air and is carried by the wind towards the opposing trenches, spreading out as it goes forward. A continuous wave of gas and air is thus formed, the color of which may vary: (a) Because of the weather conditions. In very dry air it may be almost transparent and slightly greenish in color, while in damp weather it forms a white cloud. (b) Because it may be mixed with smoke of any color.