Chapter 15: Trench Warfare (1)

General Principles.

1. Defense may be made in depth by all organizations, down to and including the platoon, or it may be made laterally.

2. The smallest active segment, be it only three men, must have a chief and a second in command, who is responsible for the proper upkeep and defense of the segment. All occupants of active segments must know all instructions which should be simple.

3. Any troops in charge of a portion of trench must never abandon it, no matter what happens, even if surrounded.

4. All ground lost must be retaken at once by immediate counter attack launched by the unit which lost the ground. As a matter of fact a counter attack is difficult for a platoon or company; it is really necessary for it to be made by a battalion.

5. Each company must provide for emplacements for mine throwers to be served by the artillery and for pneumatic guns to be served by their own men.

Instructions to be Issued by Battalion Commander.

1. Disposition of companies in sector assigned (best done by sketch showing sectors assigned to companies).

2. Special orders to companies (concerns field of fire to be obtained not only in own sector, but also in those adjoining it).

3. Improvement of defense. (Brief reports from company commanders to be followed by work being done on order of battalion commander after inspection.)

4. Organization of watching (not sentry duty) (by company commander under supervision of battalion commander).

5. Organization of observation (not sentry duty) (by company commander under supervision of battalion commander).

6. Organization of supply (procuring, routing, etc., of tools, ammunition, food, water, etc.), (by company commander under supervision of battalion commander).

7. Organization of liaison (communication) (runners, telephone, telegraph visual signaling, pigeons, etc., by company commander under the supervision of battalion commander). _All telephonic communication must be in code_.

8. Organization of supplies to include amounts to be expected daily from the rear.

9. Knowledge of enemy must be imparted to company commanders in order to assist them in making their dispositions.

10. Frequent reports to be made of existing conditions at the front for information of higher commanders.

11. Lateral defense of boyaux must not be overlooked.

12. Wide turning movements are not possible. Enveloping movements are possible only on local attacks against small portions of the hostile line after it has been pierced. All main attacks are confined to purely frontal attacks.

13. The most important obstacle is barbed wire entanglements.

14. Communication (liaison) between and co-ordination and co-operation of, the different elements of a command is of the utmost importance.

15. Artillery co-operates more closely than ever with infantry. Its reconnaissance officers accompany infantry lines in order to obtain information. _There is a certain number of artillery observers attached to each battalion of infantry_.

The general method of attack is to smother the defense with a torrent of explosive shells, kept up incessantly for one or more days, and shatter the defense so they will offer but slight resistance to the infantry; then rush forward with the infantry and seize the positions while the enemy is demoralized, and consolidate them before reenforcements can be brought up.

The artillery bombardment is necessary to prepare the way for the
infantry advance. It has for its objects:
(1) To destroy the hostile artillery, wire entanglements and
infantry trenches.
(2) To produce curtains of fire and prevent bringing up
reenforcements.

_Light guns are assigned to_ EACH BATTALION OF INFANTRY, subject only to orders of regimental and battalion commanders concerned.

Save under exceptional circumstances the light gun is always attached to the Machine Gun Company for the attack.

The essential role of the light gun is to destroy with direct fire the visible machine guns; they are employed separately and not grouped.

The infantry is divided into two classes: Holding troops--and attacking or shock troops. Holding troops are those doing routine or trench duty; shock troops are picked organizations of young and vigorous men and are kept in camps well behind the battle front. Holding troops are two weeks in and two weeks out of the trenches.

All specialist groups, _i.e._, Machine Gun Companies, etc., are officered, allowing company and battalion commanders to concentrate them, if the situation requires.

_They play the normal part in combat if they do not receive special instructions._

Attack of a Defensive Position.

Unity of command in depth must be preserved everywhere, unless there is an imperative reason for doing otherwise.

The front of each regiment should be divided between two or three battalions.

_Each battalion commander having to look after a front of from 500 to 600 yards, can exercise efficient control of his command._

In preparing for an assault, seniors must take steps to organize it and make all necessary preparations themselves, and not leave all the responsibility with the juniors.

In the assault each unit must know its special task beforehand, and it should be rehearsed in rear of the line of trenches. Each commander must know the exact time he is to start and must start on time.

The first waves of men are placed at 4 or 5 pace interval. Chief of section can command only a front of 80 to 100 paces and it is necessary to form the section in two (2) waves. The first containing the grenadiers and automatic riflemen, the latter in the center. The second wave contains the riflemen and rifle grenadiers, the latter in the center.

If the terrain is cut up by woods, villages, etc., the proportion of grenadiers may be increased by taking them from the sections in support and the automatic riflemen sent back to the second wave.

If the distance to cross exceeds 300 or 400 yards, the number of automatic riflemen should be increased.

_Two or three sections are usually placed abreast on the company front, which thus covers two to three hundred yards._

The support sections follow the leading sections of their company at about 50 yards, marching in two lines, if possible in two lines of squad columns at 20 yard intervals.

The first wave of the support is usually formed of the one-half section of specialists.

The echeloning of the specialists in front is also the most favorable formation to progress by rushes in a terrain cut up by shell holes.

The chief of section is between the two (2) waves of his section.

The captain is usually in front of the support sections.

The support sections are closely followed by a powerful line of machine guns, which are thrown into the fight when needed to reenforce the leading units.

"Trench Cleaners" usually march immediately after the leading sections and may be taken from the support sections. They are armed with pistols, knives and hand grenades.

The captain can use his section complete, or take out the specialists and use them for a particular purpose.

The specialists carry only the weapons of their specialty and have their loads lightened. The ordinary riflemen carry the usual packs and equipment.

Officers no longer lead the assault, but direct it. They are equipped with the rifle and bayonet, the same as the enlisted man.

Each unit of the first wave of the attack is given a definite objective. Different waves must not break upon the first wave.

Fire is opened by the assaulting troops only at short ranges, the advance being protected by a curtain of artillery fire. The advancing line makes use of shell holes and all other available cover.

When the first section reaches its objective it is joined by the half section of riflemen; it immediately organizes the captured ground.

Attacking From Trenches.--The commanders of brigades and battalions, with the commander of the artillery detailed to support them, study on the ground the artillery plan so far as it affects them. Immediately after the advance of the infantry begins, the artillery supporting it commences an intense bombardment with the object of forcing the enemy to take cover. At the moment laid down in the table of artillery fire the barrage lifts clear of the trench and the infantry rush in and capture it. The infantry must be taught that their success depends upon their getting within 75 yards of the barrage before it lifts, in order that they may reach the trenches before the enemy can man them. The secret of a successful assault is exact synchronization of the movements of the infantry with those of the barrage.

The pace of a barrage depends, to a certain extent, on the pace of the infantry, which varies with the condition of the ground, the length of the advance, the number of enemy trenches to be crossed, etc. It may be from 15 to 75 yards per minute. The pace of the barrage should be quicker at first, and should gradually slow down as the men become exhausted, in order to give them time to get close to the barrage and pull themselves together for the final rush.

In an attack each unit must have sufficient driving power in itself to carry it through to its objective and enable it to hold its ground when it gets there. When a number of trenches have to be carried, considerable depth will be required, and the frontage must be reduced. A brigade usually has a front in attack of 250 to 350 yards, but this may be increased to 1,000 or 1,200 yards.

A battalion should have a front of 250 to 350 yards. The battalion must be organized in depth in a series of waves. Two companies are usually put abreast in the first line and the others in the second line. Each company in both lines attacks in column of platoons at about 50 yards' distance, with intervals of three to five paces between men, so there would be eight lines of waves, of two platoons each. The 8th and 16th platoons, the two in rear forming the eighth wave, are usually not employed in the attack, but are left behind as a nucleus to form on in case of heavy casualties.

The front line must not be less than 200 yards from the enemy's front line.

The leading two or three waves are likely to meet machine gun fire, and generally move in extended order. Not more than two waves can be accommodated in one trench. Subsequent waves will move in line or in line of section columns in single file. Russian saps must be run out as far as possible across "No Man's Land" to be opened up immediately after the assault, as approach trenches. Ladders or steps are necessary to assist the leading waves in leaving the trenches, as they must move in lines. Provision must be made for bridges over the first line trenches for the rear waves. In the original assault line will be more suitable for both leading and rear waves. In later stages it is better for the rear waves to move in small and handy columns. In the original assault the distance between waves may be 75 to 100 yards; in later stages they may follow each other at 50 yards.

In the original assault, zero, or the time for the assault to begin, may be fixed for the moment at which our barrage lifts from the enemy front trench, the infantry timing their advance so as to be close under our barrage before it lifts. In the later stages zero must be the moment at which our barrage commences, and this commencement will be the signal for the infantry to leave their trenches. Each wave is assigned its own objective. All watches must be synchronized in order that all units may start off at the appointed time.

The first wave is composed of bombers and rifle grenade men, and attacks the enemy's first line of trenches. It must go straight through to its objective, following the artillery barrage as closely as possible. The second and third waves, composed of riflemen with bayonets and Lewis guns, re-enforce the first wave after the latter has occupied the enemy's first line trench, and attack the second line trench. The fourth wave takes up tools, ammunition and sand bags and assists in consolidating the line. The fifth wave is a mopping-up party to clear the enemy's dugouts. The sixth wave comprises battalion headquarters and has two Lewis guns, kept for a special purpose. The seventh and eighth waves, if used, seize and consolidate the enemy's third line trench.

Bombing squads (1 non-commissioned officer and 8 men) are on the flank of each attacking wave. Battalion bombers are assigned a special task.

All movements must be over the top of the ground. The pace throughout should be a steady walk, except for the last 30 or 40 yards, when the line should break into a steady double time, finishing up the last 10 yards with a rush.

Barrage is continued 20 or 30 minutes after the objective has been reached.

Mopping parties must be trained with great care under selected officers. They should always wear a distinguishing mark. They must at once dispose of any occupants who may have emerged from their dugouts, and picket the dugout entrances.

The ultimate unit in the assault is the platoon. It must be organized and trained as a self-contained unit, capable of producing the required proportion of riflemen, bombers, rifle bombers, Lewis gunners, and carriers, all trained to work in combination.

Assaulting troops should have twelve hours of daylight in the trenches before the assault begins, to enable them to get acquainted with the ground and get some rest. All ranks must be given a hot meal, including hot tea or coffee, before the assault.

Take every precaution to prevent the enemy from realizing that the assault is about to take place. Bayonets must not be allowed to show. No increase in rate of artillery fire. No unusual movements must be made in the trenches, and there must be no indication of the impending assault until the barrage is dropped.

When the trench has been taken, it should be consolidated at once to prevent counterattack. To protect this consolidation, throw out an outpost line, the posts consisting of one non-commissioned officer and 6 riflemen with a Lewis gun, about 150 to 200 yards apart and 100 to 300 yards beyond the line. These posts should be established in shellholes, which are to be converted into fire trenches, protected by wire entanglements, as soon as possible.

Approach trenches toward the enemy should be blockaded and hand and rifle grenadiers posted to guard them. The main captured trench should be converted at once into a fire trench facing the enemy. If it is badly knocked to pieces, a new trench may be constructed 40 or 50 yards in front of the captured line. The commander must reorganize in depth to provide supports and reserves for counterattacks. Situation reports should be sent back frequently. Rough sketches are better than messages.

Tanks follow infantry as closely as possible to deal with strong points. They are employed in sections of four.

Machine guns may be used to provide covering fire for attacking infantry, cover its withdrawal if the attack fails, fill gaps in the assaulting lines, assist in the consolidation of positions and repel counterattacks.

Lewis guns are of great value in knocking out hostile machine guns. They usually move on the flanks of the second wave of assault. Later they are used to back up patrols and to hold the outpost line while the garrison line is being consolidated.

As soon as consolidation begins, wire entanglements should be constructed. Every effort should be made to secure the objective against recapture. Any men available should be used to continue the offensive.

All commanders down to and including company commanders must keep some portion of their command as a reserve. The company commander needs his reserve to work around points which are holding against the leading lines, to protect his flanks in case the companies on his right and left are delayed in their advance and to exploit his success and gain ground to the front. He must keep it well in hand behind the company.

Battalion reserves must start with the assaulting column and get across "No Man's Land" as soon as possible; they must not get out of hand. Such a reserve is usually checked in the vicinity of the enemy's front line trench, where it can be thrown in to assist the advance or extend a flank as needed.

The brigade reserve is kept well in hand just clear of the friendly front line and support trenches. Reserves of companies and battalions must start moving over the top of the ground with the rest of the assaulting troops.

Defense Of Trenches.--The latest methods consist in constructing, supporting and strong points at the most favorable points to be held, such as villages, woods, etc. These are separated by intervals not too great for mutual support. They are of such resisting power that they must be taken before the attack can progress. In the intervals between them fire and communicating trenches are constructed, but these are only held lightly. Dummy trenches may be placed in these intervals. Lines of the various works are so traced that they bring enfilading fire on troops attacking adjacent positions. The lines need not be continuously occupied, but the obstacles extend in an unbroken line along the whole front. Wire entanglements are set in front of important positions in belts 20 feet wide, in two or three rows, each 20 yards apart.

Each supporting point usually is occupied by a battalion, and consists of a series of trenches formed into strong points, each held by a garrison of one or more platoons or a company. The supporting points are from 600 to 800 yards in depth and have a front of 600 to 1,000 yards. The first line of strong points is occupied by one or two companies in firing and cover trenches, while the remainder of the battalion occupies the support and reserve trenches. Bomb-proofs are built along the cover trenches and are connected with the firing trenches. Approach trenches are protected on both flanks by wire entanglements. Strong points in support and reserve trenches are prepared for an all-around defense and divided into two or more separate strong points by wire entanglements.

A body of infantry attacked is to oppose to the assailant its high powered weapons, machine guns, automatic rifles, rifle grenades and hand grenades and to reserve for the counter attack the grenadiers and riflemen. There is always one line upon which the resistance must be made with the greatest energy; for its defense the following methods have been found successful. Machine guns should be placed where they can secure the best flanking fire, and every one put out of action should immediately be replaced by an automatic rifle. If machine gun barrage fire is to play its role successfully at the moment of assault, the guns must survive the bombardment. Their protection is secured by placing them under shelter during the bombardment and making their emplacements as nearly invisible as possible. They should be echeloned in depth as far as practicable. They are generally placed in re-entrants of the firing trenches and cover the intervals between the adjoining supporting and strong points. Where the ground will permit they are often placed in concealed positions 20 to 30 yards in front of the trenches, to break up attacks made by hostile infantry. Not too many should be placed in the front line, and they should be echeloned in depth so as to confuse their disposition. The value of machine guns depends on the possibility of using them suddenly for brief periods, and in using them as long as they are effective. Machine guns disposed for flanking fire must be well covered by grenadiers; this is also true of automatic rifles.

Automatic rifles, rifle grenades and hand grenades are used to constitute a barrage to keep back the enemy. The entire front should be defended by a barrage of hand grenades, while the barrage of automatic rifles and rifle grenades is superposed farther to the front, up to 400 yards.

All riflemen and those grenadiers not employed in forming barrages are reserved to make a counterattack.

Companies on the second line operate on similar principles; machine guns, automatic rifles and rifle grenades are arranged so as to cover every portion of the first line that might be invaded. After a short preparation by fire from these, the grenadiers and riflemen make the counterattack.

The captains in charge of the two lines are responsible for the arrangement of the machine guns, automatic rifles and rifle grenades, the distribution of barrages and the distribution of groups for the counterattack. The real strength of the defense consists, not in holding the fire and cover trenches, nor even the support trenches, but in holding the supporting and strong points until the counterattack can be launched.

Liaison.--The question of liaison in battle is of the utmost importance, and complete co-ordination of the different arms is absolutely necessary. Each battalion sends an officer or non-commissioned officer and a cyclist to the colonel, and each colonel sends a soldier to the battalion commander.

The principal means of communication are the telephone, telegraph, wireless, aeroplane, mounted messengers, autos and motorcycles; and at the front runners, visual signals, rockets and carrier pigeons.

Each battalion commander is connected by telephone with each company commander, with the artillery observers, with the artillery commander, with his own colonel and with the adjacent battalions on either side.

The signallers of assaulting companies move with the company commander. All signallers should be given a special training in repeating a message several times to a known back station which may not be able to reply forward.

At the commencement of the assault the pigeons and pigeon carriers must be kept back at battalion headquarters, and sent forward as soon as the position has been gained.

Runners can be relied upon when all other means fail. They must be trained with their companies. Runners should be lightly equipped and wear a distinctive mark. They must be familiar with all the principal routes to all the principal centers within their battalion sector. The quicker they go the safer they are. Company and platoon runners must go forward with their respective commanders. Messages to be carried long distances will be relayed. Never send a verbal message by a runner; ignore any received; all messages must be written.

Company and battalion commanders must be prepared to assist artillery liaison officers in getting their messages back. Liaison officers must be exchanged by all the assaulting battalions with the battalion on either flank.

Trench Orders.--(Battalion): Trenches are usually divided into a certain number of bays; the number of men to defend these bays depends upon the length of trench allotted to each company. Each section is detailed to guard a certain number of bays.

Non-commissioned officers and men must always wear their equipment by day and night. Every company will "Stand To" arms daily one-half hour before dusk and one-half hour before dawn, and will remain until dismissed by the company commander.

The enemy's trenches are so close that it is very important for the men to have their rifle sights always at battle sight, so that there will be no necessity to alter their sights in case of alarm. By night all bayonets are to be fixed and half of the men on duty in the trenches are to be sitting on the firing platform with their rifles by their side. In case of attack, especially at night, it should be impressed upon the men that they fire low.

Section commanders are responsible that the men under their command have sufficient standing room for the purpose of firing over the parapet. They must have a clear field of fire, and not only be able to see the enemy trenches but the ground in the immediate vicinity of their trench. When making new trenches parapets should be at least five feet thick at the top in order to be bullet proof.

Repairs or alterations of the parapet should be reported at once by the section commander to the platoon commander, who will report it to superior authority. Repairing of trenches, fatigue, etc., will be carried on either by day or night according to company arrangement. Certain hours will be allotted for these tasks and no man is to be employed upon any kind of work out of these hours. No man should leave his post in the trenches at any time without the permission of the non-commissioned officer in charge of that post. At night there should be at least one sentry post to each ten yards of parapet. At night, double sentries should be posted if possible, and no sentry should be kept on duty for longer than an hour at a time. The arrangement should be such that when one sentry is doing his last half hour, his comrade will be doing his first half hour.

Sentries at night should always have their rifles resting on the parapet, ready to fire at a moment's notice. As few sentries as possible should be posted by day, so as to give as much rest as possible to the remainder of the men.

By day any existing loop-holes may be used by a sentry for observation purposes, but this must be strictly prohibited at night, when the sentry must look over the parapet. If a sentry is continually fired at, the section commander will post him in another position, but not too far from his original position. There is no excuse for a man going to sleep on sentry duty; if he is sick he should report the fact to the non-commissioned officer, who will report to superior authority.

An armed party of the enemy approaching the trench under a flag of truce should be halted at a distance, ordered to lay down their arms, and the matter at once reported to the company commander. If the party fails to halt when ordered to do so, or does not convey a flag of truce, they should be fired upon. An unarmed party should be halted in the same way. It is not necessary to challenge at night; open fire at once. This is modified only by special instructions.

Men especially picked for listening patrols and sharp-shooters will be given special privileges. All loud talking must be checked at night by officers and non-commissioned officers. All working parties must wear their equipment and carry their rifles. All picks and shovels will be returned after use to the company store room. Ration parties and parties carrying materials for repairs, etc., need not wear their equipment or carry rifles; they should be accompanied by a fully armed non-commissioned officer as an escort. Not more than 20 men are to be away from the company at one time; one non-commissioned officer and four men per platoon.

Rifles must be kept clean and in good condition while in the trenches. They will be cleaned every morning during an hour appointed by the company commander for the purpose. Platoon commanders will be responsible that section commanders superintend this work. All rifles except those used by sentries are to be kept in racks during the day.

Trenches must be kept in sanitary condition. Platoon commanders will be responsible for the latrines in their sections of the trenches. All water for drinking and cooking is to be taken from a water cart or tank provided for this purpose.

Stretcher bearers will be stationed at a place designated by the commanding officer. No soldier will be buried nearer than 300 yards from the trenches.

In every platoon a non-commissioned officer will be detailed for duty by day; he will do no night duty. He will post the day sentries and see that they are on the alert and carry out their orders correctly. He will be responsible for the cleanliness of his lines and will frequently visit the latrines. He will see that all loose ammunition is collected.

The platoon commander will always send a non-commissioned officer to draw rations and he will be responsible for their delivery.

The passing along of messages by word of mouth will not be used. All messages should be written.

Special instructions will be issued as to precautions against gas.

Selection of Site.

(a) Fire trench should be selected with due regard to tactical requirements and the economy of men.

(b) Every fire trench should have a good field of fire, at least 250 yards.

(c) The trenches should have the best possible cover.

(d) The forward position on a slope for the first line has the best advantage. The support trench should be on the reverse slope from 100 to 600 yards in rear of the first line to prevent direct observation and to be practically free from artillery fire. The reserve trench is usually from 1/2 to 1 mile in rear of the first line. Remember that the first line, the support line, and the reserve line are all fire trenches. Do not put them on a crest.

(e) The communicating trenches (boyaux) should be zigzagged, wide and deep, and should follow the low ground. The longest straight trench should not exceed thirty paces. The angle made by each turn should be less than 140 degrees.

(f) The fire trenches should have salients and re-entrants so as to flank the wire entanglements. The bays are usually 27 feet long with 9 feet of traverse.

(g) There are two problems in the siting of trenches, one for those to be constructed under fire and another for those that will be constructed without any danger from fire. Trenches built under fire are usually made by connecting up individual shelters made by the front line when forced to halt. Trenches built under quiet conditions can be laid out according to the best possible plan.

Trench Construction.

Several kinds of difficulties face the trench digger: Sand, clay, water and bullets. In order to overcome them he must be familiar with the general arrangement of a trench, the principles which govern its construction and the standard trench as it has been worked out in the present war at the cost of thousands of lives.

General Arrangement.--A position is a combination of trenches, consisting of: The fire trench, or first line, nearest the enemy; the cover trench, just behind the first line, where all but sentinels of the fire trench garrison are held in dugouts or shelters; the support trench, from 150 to 200 yards in rear of the cover trench, and the reserve, from 800 to 1,200 yards still further to the rear.

The support trench is placed far enough from the first line to prevent the enemy from shelling both trenches at once. By a concentration of artillery fire and a determined advance of the hostile infantry the first line may be captured. The support trench must be so organized that it will then act as a line of resistance upon which the enemy's advance will break. Lieutenant Colonel Azan of the French army says: "As long as the support trenches are strongly held, the position is not in the hands of the enemy."

The reserve is usually a _strong point_, so organized that it can maintain independent resistance for several days if necessary, should the enemy obtain control of adjacent areas.

Where possible trenches should be on reverse slopes, with the exception of the first line; but usually the outline of a trench is determined in actual combat, or is a part of hostile trench converted. Under these circumstances it cannot be arranged according to tactical ideals.

Artillery and the automatic gun are the determining factors in trench warfare to-day. The effect of artillery fire must be limited in its area as far as possible, and trenches are, therefore, cut by _traverses_, which are square blocks of earth not less than nine feet square, left every 27 feet along the trench. They should overlap the width of the trench by at least one yard, thereby limiting the effect of shell burst to a single _bay_, the 27-foot length of firing trench between two traverses. Sharp angles have the same effect as traverses, but angles of more than 120 degrees cannot be utilized in this way.

The sides of the trench are kept as nearly perpendicular as possible, to give the maximum protection from shell burst and the fall of high angle projectiles. The _parados_, the bank of earth to the rear of the trench, has been developed during the war to give protection from flying fragments of shells exploding to the rear, and to prevent the figure of a sentinel from being outlined through a loop-hole against the sky. The _berm_, a ledge or shelf left between the side of the trench and the beginning of the parados, has come into general use in order to take the weight of the parados off the earth at the immediate edge of the trench, and so prevent the reverse slope from caving in easily under bombardment or heavy rain.

Automatic guns have made it necessary to break the line of the trench at every opportunity, in order to secure a flanking fire for these arms. Auto-rifles and machine guns have tremendous effectiveness only in depth, and flanking fire gives them their greatest opportunity.

Trench Construction.--The methods of building trenches are the same whether the work is carried on under fire or not. In an attack, upon reaching the limit of advance, the men immediately dig themselves in, and later connect these individual holes to make a continuous line of trench.

Most of the digging must be done at night, and must be organized to obtain the most work with the least confusion. There are three ways of increasing the efficiency of the men. In the first of these, squad shifts, the squad leader divides his men into reliefs and gives each man a limited period of intensive work. Reliefs may be made by squads or by individuals. The second way of increasing efficiency is to induce competition among the man and squads, thus making the work a game in which each soldier's interest will be aroused in the effort to do better than the others. The third method is to assign a fixed amount of work to each man. An average task, which all ought to accomplish in a given time, is found by experience, and those who finish before their time is up are relieved from further work during that shift, and allowed to return to their shelters.

Continual care must be used to check up the tools on hand, as the men are prone to leave them where they were working rather than carry them back and forth to work. Each unit must guard its property from appropriation by neighbors on its flanks.

System of Laying Out Trenches.--The trace of the trench is first staked out, particularly at traverses and corners when the work is to be done at night. Measurements should be exact, and the men should be required to line the limits of each trench so as not to exceed them in digging. All sod should be taken up carefully and used on the parapet for concealment or on the berm to make a square back wall for the dirt of the parapet. If possible this should be done with the parados wall, so as to make it as inconspicuous as possible from the front.

Men should begin to dig at the center of the trench and throw the dirt as far out on the sides as possible, so that as they go deeper the earth can be thrown just over the berm. The slope of the sides will be kept steep and the men prevented from widening the trench as they dig. In sandy soil the sides of the trench should be allowed to reach their angle of repose (which is wider at the top than required), then the trench walls supported with _revettments_ to the proper width, which are filled in behind with sand. Always dig to full depth before beginning to revet, as it is impossible to dig deeper afterwards without loosening the revetting.

Revettments.--Every trench at points needs support, and this _revetting_ may be done with any of the following materials: Sod; corduroy of logs laid lengthwise; sand bags (size 20 in. x 10 in. x 5 in.); galvanized iron; chicken wire and cloth made in a frame about six feet long; _hurdles_, wicker mats made by driving three-inch stakes into the ground, leaving uprights as high above the ground as the depth of the trench, then weaving withes and slender saplings between the uprights; expanded metal; _gabions_, cylindrical baskets made like hurdles except that the stakes are driven in a circle; _fascines_, bundles of faggots about 10 inches in diameter by 9 feet long. The faggots are laid together on a horse or between stakes driven in the ground, then "choked," or bound tightly together, by a rope 3 feet 8 inches long with loops at each end, tightened with two stiff levers. The bundle is then bound with wire at intervals of two feet. The circumference of a fascine should be 25 inches.

Capt. Powell of the C.E.F. found during 18 months' service in the trenches, that a separate construction for the bottom and firing step from that of the parapet made repair much simpler when the trench was damaged by shell fire. The upper part of the trench usually suffers most, while the bottom section, if unattached, often remains intact and the drainage system needs only to be cleared out. If the portion above the firing step is one piece with that below, however, the whole trench has to be reconstructed.

There is nothing more important than the supports used to keep revetting in place. With sods, sand bags, concrete and gabions, a proper arrangement in the first place will make other support unnecessary.

Sod should be placed carefully, with a slope of not more than one inch on four, with the vegetation uppermost. This type is least affected by rain.

Sand Bags should be used like brickwork, laid in alternate headers (binders) and stretchers. Their use should be confined as far as possible to emergency and repair work, because after a few weeks the bags rot and cannot be moved about. If the trench wall has been demolished by artillery fire, the particles of cloth make digging out the bottom of the trench a very difficult matter.

Concrete Work has been used extensively by the Germans, but the chips fly like bullets under shell explosion, and the concrete cracks and disintegrates in severe weather. It is used in the bottom of trenches for drainage and for the firing step.

Gabions may be set into the wall of the trench and filled with earth, or used at corners to prevent the wearing down of the edge, which reduces the protective effect of the trench. Set in at a slight angle they will hold the side without further re-enforcement.

With the other forms of revetting some secondary support is required. This is usually furnished by sinking stakes into the bottom of the trench and securing their upper ends to a "dead man"--a stake or log sunk in the ground more than three feet away. The tendency is to sink the dead men too near to the trench, and to attach too many wires to one of them. It is important to sink the stakes at least one foot below the bottom of the trench. By digging holes for them instead of driving them in directly, the sides of the trench need not be disturbed by the concussion of driving the stakes. This is especially important in sandy soils. Stakes should be placed about two feet apart. Dead men should be buried deeply enough to prevent cutting by shell explosions.

Trench Armament.--A few machine guns are set in concealed emplacements along the trench to cover important salients. The automatic rifle is used over the parapet. Besides these there is the rifle grenade and trench mortar. The rifle grenade has a simple emplacement. After securing the proper elevation, the butt of the rifle is placed between posts or blocks of wood and the muzzle rested against a log on the wall of the trench. A trench mortar emplacement is dug in the rear wall of the trench, or a shell hole is utilized, care being taken to conceal it from aerial observation.

Loopholes.--Loopholes are still much in use for observation, but they are employed less and less for firing, as they are difficult to conceal from the enemy and almost useless when the enemy is close. They should cut the parapet diagonally, not directly to the front, and should be concealed by vegetation and by a curtain over the opening when they are not in use. Sheet steel plates with small peep holes are used on the parapet. They are set up with a slope to the rear to deflect bullets.

Trench Bottoms.--In clay or hard soil special arrangements must be made for drainage. Where possible the trench should have a convex surface and should be smooth. A rough bottom means delay in reliefs, and possible injuries. Where trenches are used for long periods board walks should be constructed. Under these drains or sink holes can be placed to collect water. A sink hole may be constructed by digging a pit filled with small stones, or a barrel may be sunk into the ground and filled with stone. Where there is not sufficient slope to carry off the water, or at the lowest point of a drainage system, a water hole should be dug in front of the trench large enough to handle the drainage water.

Communication Trench (or Boyau).--Running to the rear and joining the different parallel resistance trenches are communication trenches or boyaux. These are for transportation of men and material as well as for communication. Communication trenches should be made wide enough to allow travel for men with loads, should be at least seven feet deep and as smooth as possible on the bottom. Rough places will delay traffic. They are dug with turns every 20 or 30 yards to prevent their being swept by gun fire. When boyaux are built by night sharp zig-zag corners should be used, or the angles will not be acute and protection will be lost. During daylight when the directions can be seen, the construction may be a serpentine curve, with no stretch of more than 30 yards visible from one point.

Boyaux are sometimes used for lateral defence and often emplacements for automatic guns are arranged to cover stretches of them. Bombing stations are placed near by to protect the guns and to clear the boyau of the enemy. At these points the boyau is left straight for a short distance in front. Where provision is made for lateral or frontal defence by rifle fire, firing steps are constructed. If this is inconvenient for movement along the boyau, individual emplacements must be made in the side wall for firing. Sentry posts are dug at right angles to the boyau.

Arrangements for passage of men moving in opposite directions may be made by extending short spurs at the corners, enlarging the boyau at the bends, digging niches or passing points here and there, or constructing island traverses with the boyau running around on each side.

Every boyau should be marked where it meets a trench with a sign indicating the place and trench. Without this messengers, reliefs and re-enforcements may easily be lost in the maze of trenches.

Latrines should be run out about 20 feet from boyaux at points directly in rear of lateral trenches. If possible they should be placed so that men cannot enter them without passing near the platoon leaders. This will prevent men from leaving the front line, under the pretense of going to latrines, during bombardments or mining operations. The trench leading to a latrine should be constructed like a boyau, and the pit should be close to the side nearest the enemy, to give the best possible protection from shell fire. There are three types of trench latrines: Deep boxes which are covered and have rough seats; short straddle trenches or trenches equipped with a single horizontal bar, and portable cans, used where the ground or the limited space make it impossible to dig pits. These cans should be emptied daily into holes behind the trenches, which are covered after the cans are emptied into them.

Urinals should be separate from the latrines. They may be either holes about three feet deep filled with stone, troughs with a covered pit at the end, or portable cans.

Shelters. For the protection of men not actually on duty three forms of shelters are used. The _splinter-proof_ is a form of light shelter whose covering affords protection only against splinters. These are usually on the reserve line. About 12 inches to 20 inches of earth over a roof of logs or planks will afford protection from splinters and shrapnel. Curved sheets of iron may also be used. The _deep shelter_ or _bomb-proof_ is a chamber constructed by digging from the surface and constructing a roof. To protect against eight-inch shells the top of the chamber should be twenty feet below the surface. Heavy beams or sections of railroad iron are laid across the roof. Above them is a layer of earth several feet thick; then another layer of timber extending to undisturbed ground on the sides with concrete, crushed stone, metal, etc., above to make a percussion surface for exploding projectiles that penetrate the upper layer of earth. This layer fills in the rest of the space to the level of the ground.

Shelters should not exceed six feet in width, but can be of any length. This will prevent the crushing in of the roof timber by the explosion of a projectile buried in the upper layer of earth. The principles of constructing shelters will be considered under "Dugouts," as they are similar for the two types.

Dugouts are chambers tunnelled into the ground with twenty feet or more of undisturbed earth above them. They are used in the cover trenches and sometimes in the first line. Enough of them must be built to shelter the garrison of each sector, allowing one man per yard of front. They must also be built for machine gun and trench mortar detachments.

Sentries must be stationed in observation posts which command the ground in front of each dugout. They must be connected with the dugouts by telephone or speaking tube.

Position.--Dugouts must always be on the side of the trench toward the enemy. This prevents flying shells from falling into the entrances. They should connect with lateral trenches, not with boyaux, as men at the entrance obstruct traffic through the boyaux.

Entrances and exits must be well concealed, with not less than five feet of head cover. This should be provided with a bursting layer. All dugouts must have at least two openings, one on the opposite side of the traverse or angle from the other. It is well to have an exit behind the parados leading to a surprise position for a machine gun and bombers. All openings must have a sill 6 inches to 8 inches high, to prevent water from entering the dugout.

Galleries leading to dugouts should be built at an incline of 45 degrees. Their dimensions should be 2 feet 6 inches by 6 feet. Frames are of squared timber. The sill and two side posts should be not less than 6 inches square, and the frames in the passageways 2 feet 6 inches by 4 feet 6 inches. They must be placed at right angles to the slope of the gallery, with distance pieces between uprights. In treacherous soil the frames rest on sills. Steps in the passageway are 1 foot broad and 1 foot high.

Bomb-traps, extensions of the gallery about 3 feet long, should be dug beyond the point where the entrance to the dugout chamber leads off from the gallery. These will catch bombs thrown in from the surface and protect the chamber from the effects of their explosion.

Interior. The standard section is 6 feet by 8 feet, to allow for bunks on each side. Frames of 6 by 6 timber spaced 2 feet 6 inches apart support the sides and roof. Roof planking should be 2 inches thick, and the sides should be covered with 1-1/2 inch plank or corrugated iron. Two shovels and two picks for emergencies should always be kept in each dugout. The construction of the chamber should be that of a very strong box, so that it will stand strain, if necessary, from within as well as from without.

Depots for Supplies must be near the headquarters of the platoon, company, battalion and regiment. Shelters may be made with ammunition boxes set into the side of the trench. Places should be provided for the following: Food, ammunition for rifles and auto-rifles, grenades, rockets, tools and other supplies. Places must also be arranged in the front line for ammunition, rockets and hand and rifle grenades.

Telephones. Communication is established as speedily as possible with the various units. In the forward trenches wires do not last long under bombardment and fire left open along the side of the trench, where quick repairs can be made. All soldiers must be taught to respect these wires and to care for them when they are found under foot or hanging. Conduits are dug for wires to battalion and regimental headquarters, and these are fairly safe from shell fire.

Departure Parallel. In preparing for an advance upon the enemy, a straight line trench without traverses, and with steps at the end for exit to the surface, is built in front of the first line trench. This line of departure is generally brought within about 200 yards of the hostile line by means of _saps_, short trenches run out from the front line to the new parallel. Since this line of departure can be seen by the enemy, it is sometimes better to construct steps in the front line trench itself, or when possible to build a _Russian sap_. This is a tunnel very near the ground, which can be broken through at a moment's notice when troops are ready to advance.

Machine Gun Emplacements.--Shell-holes with a good field of fire and emplacements along boyaux are the best location for machine guns. Few guns are placed in the front line, and these only at strong points in the line, which command a maximum field of effectiveness. Shell-holes may be imitated for machine gun emplacements, but in any case they should be connected by underground passage with the trenches. Thus when trenches are destroyed by bombardment the machine guns remain intact. The field of fire for each machine gun should be carefully determined and marked by three stakes, one for the position of the gun, the other two for the limits of the field of fire. Using these as guides, the gun can be fired correctly at night. During the day it is never left in place nor fired from its actual emplacement.

Listening Posts.--These stations are usually carried out to the edge of the entanglements nearest the enemy. The listening station must be large enough for half a squad, and often has an automatic rifle and grenade thrower. There should be not more than two posts for each battalion. They are not occupied during the day. They are hard to defend and easily captured by a raiding party which cuts the wire to one of the flanks and comes in from the rear. The boyau leading to the post should be zig-zagged. The post itself should be deep enough for good head cover.

Wire Entanglements.--The object of the entanglement is not to stop completely the advance of the enemy, but to delay him at close range under machine gun, auto rifle and rifle fire, and within range of grenades and bombs. Entanglements should be concealed as much as possible from the enemy's trenches and from aerial observation. If possible, they should be placed on a reverse slope or in a dead angle. They should be from 50 to 100 yards in front of the trench, so that artillery fire directed upon the trench will not be effective on the wire. At the same time the wire must not be far enough advanced so that the enemy's raiding parties can cut the entanglements.

Wire entanglements are classified as high entanglements, low entanglements and loose wire.

High Entanglements are strung on metal or wood posts about four feet high, both wire and posts being painted for camouflage. The driving of posts must be muffled, and metal screw posts are used when near the enemy's line. Posts are placed in two parallel lines, two yards apart, spaced alternately so that the posts in one line are opposite the middle of the interval in the other.