Gas attacks may be carried out in two ways, by asphyxiating shells or by waves of gas.
The shelling of a position with asphyxiating shells is made to neutralize the action of its defenders and, if possible, to kill and wound some of them. Asphyxiating shells are used in counter-battery fire against the enemy’s artillery emplacements. They are also used for shelling a woods in which troops are located and against strong points of the hostile position, either during an offensive period or to carry out attrition of the enemy. Such shelling is also carried out for an offensive, either in the preparation or for the protection of theflanks during the attack. Asphyxiating shells may be thrown on a village or strong point in rear or on the flank of the enemy’s position where he may organize a counterattack.
Gas waves are used against the enemy’s position with or without following up with the infantry for a raid or an attack. Usually the liquified gas is brought to the first lines in cylinders under heavy pressure. These cylinders must be properly protected from hostile fire until the time that they are to be used. With a favorable wind, the gas is carried across “No Man’s Land” and into the enemy’s position. Gas waves, of course, are more efficient than asphyxiating shells, but the use of the former method is more difficult as it takes special apparatus and a trained personnel, and can be used only under favorable atmospheric conditions.
Protections against Gas.In general, protective measures against gas waves are the same as against asphyxiating shells. The individual protective apparatus is the gas mask. The essential part of a mask is composed of several layers of porous material containing a chemical that will neutralize the poisonous gas. The gas mask has an efficiency of several hours. Each man carries a gas mask and there are also a certain number keptin reserve in the different depots of the sector. Each gas mask must be properly adjusted and it is the duty of each officer and non-commissioned officer to ascertain that each man in the company has a gas mask in good condition. He must always carry the same.
Each man is trained to put on his mask rapidly. Standing orders compel the man to put on his gas mask immediately the alarm is given or upon his detection of gas by color or odor. Frequent exercises are held to perfect the men in putting on their gas masks rapidly. This drill may be held at the same time as the “stand to” exercises are carried out. The men must have confidence in their gas masks. For this purpose, each man is sent through a “chlorine chamber” several times to give him confidence that, although the gas may be of great density, it has no disagreeable effects.
There are also collective protective apparatuses used in dugouts. Each large shelter possesses such apparatus. Besides this, the entrances and openings of each dugout will be closed by a double canvas impregnated with a special chemical solution to neutralize the gas.
Special Precautionary Measures.First, there is established a system of bells, sirens, and klaxons which are used by the watchersto give the signal of alarm. This signal is taken up and repeated in all parts of the position and to the rear. Careful observation on the part of a garrison may detect signs of a coming gas attack. Metallic noises in the hostile line may indicate the transportation of gas cylinders. Very often the enemy will use little balloons to ascertain the velocity and direction of the wind. Foggy weather is a special time of danger.
In each sector or regiment, an officer is in charge of the maintenance of protective gas apparatus and all the measures against gas attack. With the proper precautionary measures and application of the protective measures, the gas attack is not very dangerous.