Chapter 46

TRENCH AND MINE WARFARE[14]

=1194. Asphyxiating gases.= The asphyxiating gases employed may be divided into three general classes, viz:

_Suffocating gases_, the most common of which are carbonic and nitrogen.

_Poisonous gases_, under which head come carbon monoxide and cyanogen.

_Gases which affect the throat and bronchial tubes_, such as chlorine and bromine. The latter class is most commonly employed.

The methods usually employed for liberating these gases are to have a plant some distance in rear of the trenches where the gas is stored under pressure and carried to the trenches through pipes, where it can be liberated towards the enemy's trenches when there is a favorable wind to carry it along; or, the gas may be carried in cylinders or other containers and liberated at the desired points. Hand grenades or bombs are also employed which, upon bursting, liberate the gas or in some cases scatter acids or caustic soda. Some of these bombs contain a chemical which when liberated affects the eyes, causing impaired vision. The Germans employ several kinds of shell containing gases of different densities, one of heavy gas fired as a curtain to the rear to permit reinforcement of the trenches and another of lighter gas to demolish the trenches and destroy the firing line. As a general rule these gases are employed when the fire trenches of the opposing forces are close together though the shell containers may be used at long ranges. All of these gases being heavier than air lie close to the ground and flow over and down into the trenches.

=1195. Protection against gases.= The best protection against these gases, is a mask of some kind. The commonest form employed is a flexible mask that conforms to the head, is fitted with glass for seeing through, and has an arrangement of tubes and valves which require the wearer to inhale through his nose and exhale through his mouth.

These masks have an absorbent composed of hyposulphite of sodium or of 72 per cent of the nitrous thiosulphate and 28 per cent of bicarbonate of soda. This absorbent placed so that air must be breathed through it, neutralizes the acids in the gases. Soldiers are provided with these masks, sometimes with two of them, and are required to have them renewed every three months.

Trench sprays may be used to spray neutralizing liquid in the trenches to kill the gases.

The _favorable conditions_ for the employment of gases are wind blowing toward the enemy's trenches and warm weather. _Unfavorable conditions_ are rain, cold, and adverse winds.

In some localities weather vanes placed in the direction of the enemy's trenches and arranged so that they may be watched at night give an indication of favorable winds and enable the defender to prepare for a gas attack.

Before the masks were provided bonfires were prepared of oil soaked materials which; when ignited, produced an intense heat and the resulting column of air diverted the gas clouds.

=1196. Liquid fire.= By use of hand or motor driven pumps, and a light grade of petroleum, columns of liquid fire may be squirted into the opposing trenches. If the oil should fail to remain lighted it may be fired by bursting hand grenades or throwing fire balls into the trenches. This means of attack is employed when opposing trenches are close together.

As a defense measure ditches may be dug in front of the trenches and filled with a porous material which is then soaked with oil. Heavy oils, being hard to ignite, are not dangerous to the defense, and will remain with little loss for a long time. To make sure of prompt ignition gas lines are laid in the ditches. When turned on the gas readily ignites and the resulting fire produces great heat. Wire or barbed wire looped in the ditches and staked down makes this a formidable obstacle.

=1197. Grenades and bombs= are containers, designed to be thrown by hand, by a sling, fired as a rocket or from specially constructed mortars, or dropped from aerial craft. They burst by time or percussion fuses and may be improvised in a variety of forms and are most useful in close attack or defense. Their effect is local but they are very demoralizing to men's nerves.

=1198. Hand grenades= are designed to be thrown by the hand and vary greatly in construction. In general, however, they consist of a container filled with bullets or pieces of iron or other metal in the center of which is a charge of high explosive which scatters the bullets or fragments with deadly effect. The three methods of discharging a hand grenade are:

_By time fuse_ which is lighted by hand. About 5 to 9 seconds is the time from ignition until the grenade bursts. This does not give the defender time to pick up the bomb and throw it out of the trench.

_By friction primer and fuse._ In this form of hand grenade a strap on the wrist with a short line attached with a hook on the end of it serves, when the hook is engaged in the ring of the grenade, to jerk the primer when the grenade is thrown. This automatically ignites the fuse which bursts the grenade in from 4 to 5 seconds.

_By percussion._ In this form of grenade the charge is fired when the grenade strikes the ground or object at which it is thrown. In this form of grenade a safety pin holds the plunger from the cap. When the grenade is to be thrown the safety pin is withdrawn.

As a general rule fuse burns at the rate of 1 inch in 1 and 1/4 seconds; however each lot of fuse should be tested.

Figs. 1 and 2 show two forms of improvised grenades. Common cans, such as preserved fruits and vegetables are shipped in commercially, make good containers. The usual weight of a hand grenade is about 1-1/2 pounds.

=1199. Other methods of throwing grenades.= Many grenades have been designed to be fired from the ordinary rifle. This grenade has a rod which is inserted in the barrel of the rifle. A special charge of powder is used in the cartridge from which the bullet has been withdrawn.

Common slings, catapults, and other devises have been frequently used.

=1200. Aerial mines.= (Fig. 3.) This form of grenade is very heavy, often weighing 200 pounds and is fired from a trench mortar.

=1201. Winged torpedo.= (Fig. 4.) This projectile is fitted with three winged vanes which steady its flight and greatly increase the accuracy. A rod fitted into its base enables it to be fired from a comparatively small trench, mortar. The torpedo weighs about 40 pounds and the mortar 200 pounds. The mortar, being light, can be carried from one part of the trench to another by two men.

The aerial mine and winged torpedo may be used effectively to beat down the enemy's defenses, destroying his sand bags and trenches, and cutting away wire entanglements and other obstacles. The winged torpedo having a greater range (500 yards) and being more accurate, is the more effective.

=1202. Bombs from air-craft= are some form of high explosive bomb which burst on striking. Another type of bomb used by aeroplanes consists of a container filled with steel darts. The bursting charge is fired by a fuse. The operator usually cuts the fuse so that the bomb will burst at a considerable altitude. The steel darts are scattered in all directions and have sufficient velocity to pass through a man or horse.

=1203. Protection against hand grenades.= (Fig. 5.) For protection against hand grenades and bombs a screen of wire netting may be erected in front of the trenches and arranged at such a slope that most of the grenades passing over the screen will clear the trench while those striking the netting will roll away from the trench. This protection is very satisfactory for communications, machine gun emplacements, etc., but, is of doubtful value in fire trenches as it does not permit an easy offensive by the defenders.

=1204. Tanks.= The so-called "tanks," first used by the British armies in the battle of the Somme in September, 1916, are in reality armored caterpillar tractors carrying machine guns and capable of traversing rough ground, smashing down trees and entanglements, and passing across the ground between the opposing trenches over the shell holes made by the opposing artillery.

The machinery, guns and crew are contained in an armored body and the two tractor belts extend to full length on either side, being so arranged that the tank can climb a steep slope. From the meager data obtainable it would appear that the tanks carry from 4 to 6 machine guns in armored projections built out from the sides. These are provided with revolving shields permitting two guns to fire in any direction at one time.

The principle of the tractor is similar to that of those manufactured in the United States and used commercially in reclamation work. The addition of the armored body and guns makes the "military tank."

These "tanks" have proven of great value in village fighting, by smashing down barricades and driving machine guns from their positions in cellars and houses. They have also been used with some success in destroying obstacles.

The power of these new engines may be judged from their ability to smash down trees six inches in diameter and by means of cables to uproot trees as large as 15 inches in diameter.

These "tanks" are proof against rifle and machine gun fire, but are unable to withstand even light artillery.

=1205. Helmets.= Steel helmets made their appearance in the European war in 1915, as a protection to the soldier's head against rifle, machine gun and shrapnel fire. So successful were they that they are being furnished to all troops on the battlefield. Already several millions have been supplied. Where heretofore head wounds accounted for over 20 per cent of the casualties in trench warfare, the percentage has been reduced by the wearing of helmets to about one half per cent. While the helmet does not afford complete protection against rifle and shrapnel fire, it has been found that hits result only in severe concussion, where before fatal wound resulted. These helmets are painted khaki color.

=1206. Masks.= Steel masks for sentinels and snipers have been adopted by the Germans. This mask covers the head and face with curved surfaces which deflect bullets. Small eye holes permit a clear view of the target and a small section is omitted in the lower right side to permit bringing the rifle against the cheek in firing.

=1207. Periscopes.= Periscopes have been universally adopted in trench warfare for observing the enemy while keeping completely under cover. It is a simple arrangement of two mirrors in a vertical tube. The upper reflects the image of the object to the lower mirror which in turn reflects it to the eye of the observer. By raising the top of the periscope above the parapet the soldier can watch the foreground while at the same time remaining completely concealed himself.

A more elaborate periscope for the control of artillery fire has a collapsible tube which may be extended and elevated to a height of 75 feet.

=1208. Sniperscope.= This is a combination of the periscope and rifle by means of which a soldier can aim and fire his piece at an object without exposing himself above the parapet.

=1209. Aids to firing.= Rifles laid in notched boards placed in the parapet may be sighted and prepared for night firing, or a wire stretched just outside of the loophole on which the barrel of the rifle can rest when in the proper firing position to cover certain points, enables the soldier to fire effectively at night when it is too dark to aim.

=1210. Mining.= Military mining consists of digging communications and chambers underground and placing therein charges of explosives and firing such charges. Mining is slow and restricted in its application and therefore this method of attack is used against very strong points of the enemy's line,--a salient, a building, or other point,--held in great force. The aim in mine warfare is to make a sudden breach in the enemy's trench, destroy the flanking supports which could be used to stop this breach and then to take the trench by assault and organize it for defense before the enemy's forces, disorganized from the explosion, can recover.

Sometimes mines are placed in front of the trenches and exploded electrically when the enemy reaches them in attempting an assault.

=1211. Countermining.= The enemy, when mining operations are suspected, runs out tunnels to meet the opposing mine. Sometimes listening galleries are driven underground and men posted to detect the sound of mining operations. Once the direction of the opposing tunnel is discovered a charge of explosive is laid across its approach and fired at a moment when it will cause the most damage.

FOOTNOTES:

[14] To those desiring to go into the subject of trench warfare in detail, the author would recommend "Trench Warfare," by himself. George Banta Publishing Co., Menasha, Wis.; $1.25.