TRENCH WARFARE
TRENCH
WARFARE
A MANUAL FOR OFFICERS AND MEN
BY
J. S. SMITH
SECOND LIEUTENANT WITH THE BRITISH
EXPEDITIONARY FORCE
[Illustration]
NEW YORK
E. P. DUTTON & CO.
681 FIFTH AVENUE
COPYRIGHT, 1917,
BY E. P. DUTTON & CO.
Printed in the United States of America
TO
THE AMERICAN OFFICERS AND MEN
WHO SERVED AND
ARE SERVING THEIR COUNTRY
UNDER ALIEN FLAGS
INTRODUCTION
It is a safe bet that when the German army started for Paris they had
plans for use in the event of disaster. The disaster occurred, and a
new type of warfare requiring the highest courage, skill and endurance
was born. I say born because although trench warfare was known before,
it died in birth compared to this war, for the amount of science,
energy and variety of weapons used.
More earth has been removed by a combination of man, pick and shovel
in making these trenches than was excavated to make the Panama Canal
possible, and in less time.
It is my object in this book to give a faint idea and knowledge of the
trenches, and to approximately explain the way warfare is carried on,
and I offer the information contained herein as a basic foundation on
which to use the further knowledge you will gain as an officer, and
which, for obvious reasons, I will not and cannot give here.
The notes are all taken from different courses of instruction, and
observations made during thirty-one months of service, fifteen of which
was spent on the Belgian and French fronts, both as private and officer
in the infantry service.
I do not lay down my information as expert and final by any means,
but as trench warfare changes from day to day, improvements are made,
old ideas discarded, new ones tried, it can be seen that nothing can
be laid down as a cut and dried rule, but the principles of trench
building, generally speaking, remain the same. This I have endeavored
to give, along with a few other notes which will give an idea of the
many and varied tasks that a second lieutenant must know before he is
fit to take hold of men in a place such as the Western Front, where
there is very seldom a chance to rectify mistakes, or to experiment
more than once.
When the British and French armies started their retreat from Mons, as
far as the British army was concerned they were hampered by their want
of knowledge of trench warfare as used in the South African war. The
men retired day by day, hardly staying in one place long enough to dig
themselves in. At that time for digging a trench system, one valuable
lesson was learned, and that was, that the hole such as they had been
taught to make in just such circumstances as they were up against then
was no good, as it offered them no protection from overhead shrapnel,
and at the best of times made a very poor shelter. This hole used to be
dug a little more than the width of a man and straight back his full
length, he naturally throwing the dirt in front of him and thus making
a little parapet.
When the battle of the Marne commenced and the British and the French
drove forward, this valuable lesson and many others had been learned,
so that when the armies had reached the limits of their endurance,
instead of digging themselves in in the old style, a new system was
used, greatly assisted by shell fire.
A round hole was dug by each man to fit his individual size and made
to suit himself. Here he squatted and fought, if necessary, and got
what rest was possible during that day, with the enemies’ line at
distances varying from 100 to 500 yards from him. During the night,
these men when not fighting or bothered by counter-attacks, or trying
to obtain rations, water and the many necessaries that a fighting man
requires, deepened their shelters and joined them together by little
narrow ditches. During the next day there might be bitter fighting,
so it would be even possible that other troops would come up and
relieve during the early dusk. The relieved troops would retire a short
distance and dig themselves another row of little holes where they
might act as supports in case the temporary front line gave. During
that night the holes on the front line would be enlarged until they
finally joined and gradually without deliberate intention the trench
became a permanent feature. Then the line slightly in the rear became
connected with the front line system by what were then nothing more or
less than ditches and this was the birth of the present system which
now stretches from the sea to Switzerland.
The trench systems now generally consist of three complete lines or
systems of trenches, each system being self-supporting and independent
of the other. The second and third systems are generally laid with
due consideration to protection, fields of fire, and all the other
tactical requirements that are necessary to such a system; it being
impossible in the majority of cases to keep these points in mind during
the building of the first or original line. These systems generally run
to a depth of six to eight miles from the front firing line. They are
so constructed that when a firing line has been broken through to any
great extent, what was formerly a communication trench at once becomes
a fire trench, and serves to bring a heavy enfilade fire on the troops
occupying the captured area.
It must be remembered that the considerations, arguments, and notes
laid down in this book cannot, under stress of circumstances, always be
acted on. It will be found, however, that a certain amount of training
and of study as to the conditions governing the sighting, building, and
living in these trenches, will cause a man, even under great stress
of excitement, to look for and try to obtain the ideal as a matter of
habit and without giving much time and thought to the question.
The Art of War is “the greatest amount of common sense used in the
shortest possible time.”
J. S. S.
EDITOR’S NOTE
Mr. J. S. Smith, the author of this book, is an American, born in
Philadelphia, who enlisted in the 29th Vancouver Battalion in the fall
of 1914. He saw service along the Belgian front, and in August 1916 was
given a commission in the British Army. He is now (June, 1917) serving
with the British Expeditionary Force on the French front.
CONTENTS
PAGE
INTRODUCTION vii
LOCATION AND CONSTRUCTION OF TRENCHES 1
DUGOUTS 19
RESISTANCE OF ROOFING MATERIALS 24
DUMPS 25
LATRINES 27
REVETMENTS 28
Sand Bags 29
Corrugated Iron 32
Fire Platforms 34
TRAVERSES 36
LISTENING POSTS 38
OBSERVATION POSTS 43
Loopholes for firing 43
SUPPORT TRENCHES AND SUPPORT DUGOUTS 45
SUPPORT POINTS 46
RESERVE DUGOUTS 47
SECOND LINE 47
COMMUNICATION TRENCHES 48
SKETCH OF TRENCH SYSTEM 56
Section I 56
Section II 58
Section III 63
Section IV 67
TELEPHONE LINES 68
RECESSES 69
NOTICE BOARDS 70
TRENCH DRAINAGE 72
FLOORBOARDS 77
BRUSHWOOD AND STRAW 79
WORKING PARTIES 80
RELIEFS 81
TRAVERSED FIRE TRENCHES 83
OBSTACLES AND ENTANGLEMENTS 84
LOW WIRE ENTANGLEMENTS 85
HIGH WIRE ENTANGLEMENTS 86
ABATIS 88
BARRICADES 88
INUNDATIONS 89
FOUGASSES 89
ORGANIZATION OF BOMBING SQUADS 90
TRAINING 91
EXPLOSIVES 101
BOMBS 103
PERCUSSION BOMBS
Hand Grenade No. 1 103
Hand Grenade No. 2 105
Rifle Grenade No. 3 105
IGNITION BOMBS
Hand Grenade Nos. 6 and 7 107
Hand Grenade Nos. 8 and 9 108
Pitcher Hand Grenade 108
Oval Hand Grenade 110
Ball Hand Grenade 110
Jam-pot Bombs 110
MECHANICAL BOMBS
Hand Grenade No. 5 or Mills’ Grenade 111
GAS WARFARE 113
Tear Shells 116
GAS MASKS OR RESPIRATORS 119
DUTIES OF A PLATOON COMMANDER AT THE FRONT 121
GOING INTO THE TRENCHES 122
IN THE FIRING LINE 123
OBSERVATION 125
Inspection 126
SENTRIES 127
RIFLES 128
PREPARATORY TO ENTERING TRENCHES 130
TAKING OVER TRENCHES 131
SNIPING 131
PATROLS 132
DUTIES OF AN OFFICER 134
HOW TO FIRE A MACHINE GUN IN CASE OF EMERGENCY 140
Lewis Gun 141
Vicker’s Automatic 141
Stoppages 142
PREVENTION OF FROST BITES AND TRENCH FEET 142
TRENCH WARFARE
LOCATION AND CONSTRUCTION OF TRENCHES
In locating the site for a defensive firing line, it must be divided
into three sections:--firing line, immediate support and reserves. In
doing this several opposing factors should be taken into consideration
and their relative importance judged according to the special
circumstances and objects in view, keeping in mind the probable lines
and manner of defense of the enemy, and whether the trenches are for
permanent or for temporary use.
This may be summarized under two heads: first, with the object of
attaining the greatest field that can be covered by defensive fire;
and, second, the greatest security from offensive fire.
It will even be found that these two constructions will be in conflict.
Trenches placed behind the crest of a hill, say fifty to one hundred
and fifty yards from the top, will hamper the accuracy of the enemy’s
artillery fire. Shooting, to be effective, calls for a high rate of
accuracy, and here the only observations possible are from aircraft
and balloons; but the enemy side of the hill will be raised ground to
the occupants of the trench. At night large numbers of the enemy could
collect there, and the dangerous space to them would merely be the
distance from your fire trench to the crest of the hill.
The enemy could and would entrench themselves on their side of the
crest and by raising their parapet enjoy the advantage of a higher
front, which would eventually lead to their entirely controlling the
area behind your trenches, which are continually used by the relief and
fatigue parties.
It is a principle that grazing rifle fire upon a defensive enemy is
more effective than plunging fire, but any entrenched position higher
than your own held by an enemy gives them a tremendous advantage.
Regardless of what opinion may be held as to the maximum depth of a
field of fire required to meet or repel attacks, whether in masse
or open order, it should be obvious that the greater the depth of
the field of fire and the more extensive the view of the enemy’s
operations, the better it will be for the defending forces.
Protection from and localization of artillery fire must be provided by
the internal construction of the trench rather than by a position that
protects but also restricts the field of fire. There are frequently
found in front of a firing line small areas of ground which are not
covered by direct fire from your trench. A flanking fire frequently
can cover these areas, but in spite of this, they must be watched
constantly by means of listening posts or concealed observation posts,
which may be hidden by the banks of rivers, hedges, ruined houses, or
whatever natural existing concealment renders observation possible.
At night, it is a safe principle to support listening posts by
automatic rifles, trip wires with noise making arrangements attached
to them as common sense under the circumstances dictates. Great care
and caution must always be taken to prevent the discovery of these
listening posts by the enemy, and when discovered, alternative posts
should be made or greater care taken for the protection of the men
occupying these posts, such as overhead protection by mesh wire against
bombing, and the upkeep of a small supply of bombs and close-range
weapons in the post. The important trenches on the front having been
located with a view of protecting the immediate front and with due
regard to their relation, tactically, to the other trenches already
located, the connecting trenches obviously must be subservient to the
more important ones. Every endeavor must be made to avoid enfilade
fires in the flanks, to give and to receive mutual support, and in
particular to support those flanks which are not protected otherwise.
It is an essential consideration in the location of all these trenches
that lateral communications can be established, and that supplies,
supports, reserves, ammunition, etc., together with the means of
retiring if necessary be taken into account. The distance from the
water supplies and the possibility of concealing approaches is a
further governing factor, although in many cases an ideal condition
cannot be realized.
Then there is the counter attack, in case the fire trench should be
taken, and the kind of soil which is so essential to its relation to
bad weather and water seepage--these also require thought and study.
These things are main considerations to be kept in mind after a line
has been settled on, whether during attack or whether siting trenches
under common circumstances. It is not expected and is not necessary,
when trying to obtain a position during attack, to keep all of these
conditions in mind, but it is essential that when the attack has been
finished and things return to slightly more normal circumstances, that
these things be given instant consideration and proper action taken.
Were such a thing as concealment possible, it should be the first
thing of importance to be kept in mind. Listening posts, machine
gun positions, reserve dugouts, company, battalion and regimental
headquarters, and similar things, at some distance behind or on fire
lines, may be concealed, but fire-trenches are sure to be observed
sooner or later (mostly sooner) by aeroplane and other means of
observation, and it is best that one should admit the impracticability
of concealment at once and take the proper protective measures. If
opportunity for concealment offers itself, as it may do, according to
the lay of the land, it should be taken always. It should always be
kept in mind that one should try to place himself in the position of
having the enemy’s point of view, both from his trenches and his aerial
observations.
Advantage should be taken and even care given along trenches to the
extensive cultivation of the weeds, grasses, etc., that may grow
rapidly in the excavated soil.
It is, and always will be, a matter of much argument that trenches
should not be dug near hedges, ditches, roads or rows of trees, on
account of easy ranging mark given to the enemy artillery. In a country
where such things are scarce, the idea may have a leg to stand on, but
certainly to the Western Front it does not apply. It does not take
artillery a moment to approximate by ranging shot, check by deduction
or addition the range of trenches in any area, even if lying along
a hedge or road. The ditch or hedge in some cases will provide the
starting of a trench and offer fair amount of cover from fire to the
troops working. A ditch immediately in front or behind the trench
greatly helps to solve the many and varied difficulties of drainage,
and when in front of a trench, can be made into a formidable obstacle,
generally by throwing in varied lengths of barbed wire. Trenches under
the cover of a hedge are very often safe from aerial observation, and
even when located, sniping and observation can be carried on from them
if the contours of the ground are favorable. It is always possible
to do a certain amount of repairing and moving of troops only when
unobserved from the enemy’s trenches. If advantage is not taken of
these natural protections, such as hedges and trees, then they must be
destroyed.
It is obvious that a great deal of labor can be lost and work thrown
away if a policy is not adopted and continued. Battalions relieving one
another up and down the line may waste a tremendous amount of labor
unless the relieved officer’s policy is explained. If each commanding
officer of a relieving battalion is permitted to air his own theories,
duplication of work and lack of continuity will exist. Therefore, it is
essential that the officers relieving the trench be thoroughly informed
of work going on. With this object in view some of the officers of the
relieving battalion should do a tour of duty (about 24 hours) before
their troops take over the trench. An Officer and Non-Commissioned
Officer are detailed from each relieving company for this duty. In the
trench this officer is instructed by the senior officer present, and
the non-commissioned officer by the ranking non-commissioned officer,
in the policy to be continued. The commanding officer of the occupying
company should have a sketch map of his sector of trench which he
turns over to the relieving officer. This map should show the work
under construction; proposed work; wire defenses; and if possible, the
enemies machine gun emplacements, observation posts, snipers and work
in progress. The notes accompanying the map should give the general
conditions concerning the work--depth to which it is safe to dig,
nature of soil, conditions regarding drainage, and all information in
regard to the enemies’ activities during the period of occupancy. In
addition, the relieving officer has the trench diary showing all the
information covering every minute detail of the happenings during that
company’s stay in the trenches. This diary is a continuous record of
that particular sector and remains with the occupying company until
it is relieved and then passes into the possession of the relieving
half company, and so on, forming a continuous running record of the
policy applying to the upkeep and methods employed therein. This diary,
unless it is buried to avoid falling into the hands of the enemy, will
continue until the end of the war. So every half company inherits one
from his predecessor in the line upon its assuming the obligations
previously assumed by its fore-runner, thus preventing a duplication of
work and assuring continuity of endeavor.
There are certain obvious requirements that have to become rules. When
required to fill sandbags, always look for the nearest excavation
being made and fill from there, if distance permits.
As a matter of fact, in every trench there is a continuous revetting,
widening of communications or control trenches, or driving of a tunnel
to a listening post.
[Illustration: _A--Parapet Traverse_
_B--Parados Traverse_
_TRAVERSED & RECESSED TRENCH._]
Inasmuch as the time for filling sandbags is never ending, if work
is being done and the earth is not absolutely needed for parapet
or parados, the earth, if dry, should be put in sandbags, and, if
necessary, stored until it is needed. The repair work that is most
necessary takes precedent and is about as follows: Any damage to
parados or traverses should be immediately attended to. During the
night any damage to the wire entanglements must be repaired. Drainage
comes next in order of importance, and this involves the digging of
sumps and deepening of the drainage bottom. These are the repairs, but
improvements must continually be made in the dugouts and communication
trenches.
The ultimate design of a fire-trench depends upon its closeness
to the enemy. When the latter are within 150 yards, the traversed
fire-trench shown in sketch should be employed, as it provides adequate
accommodation and protection for men who may at any moment be called
upon to make use of bomb, bayonet and bullet; but if the enemy trenches
are more than 150 yards distant, the ultimate design would depend upon
the number of machine guns and automatic rifles available. Each of
these guns has a firing capacity of about 25 rifles. Each gun therefore
gives a reduction in the number of men required to hold the line, and
in consequence reduces the amount of trench needed to protect these men.
A design, known as the “T” shaped fire-trench, makes an adaptable basis
for entrenching under these conditions. Many lengths of a continuous
traversed trench have no great field of fire, and yet, having been dug,
they must be held, and unless properly held and kept in repair, they
naturally become a source of danger.
As shown in the sketch, a traversed trench consists of a series of
fire-bays interrupted by a series of traverses. The object of these
being to localize the effect of shells or bombs landing in a fire-bay,
and preventing enfilade fire down the length of the trench, as well as
localizing any entry of the enemy into your line.
Dimensions vary up and down the line. Sometimes according to the lay
of the land, sometimes according to the opinions, whims or fancies of
the regiments making them, but the following dimensions should be kept
in mind, and it will be found that they show the average of the whole
general line on the Western Front.
Fire-bays generally are from 12 to 18 feet long (defendable by 4 to 6
men, but accommodating 8 to 12, when necessary) plus a 2-ft. covered
sentry box recessed into the traverse and giving room for one more
man; this depending entirely on the energy and initiative of the men
occupying the section.
Every traverse averages 9´ x 9´ which includes a fairly liberal
allowance for wear and tear, and is the minimum allowance for stopping
enfilade fire and localizing fire. As the width from front to rear
varies, depending on the amount of shell fire, it should be wide
enough to allow a certain amount of lateral traffic without interfering
with those who may be firing. Three feet may be taken as the maximum
width at the bottom of the trench, that is, 1½´ for traffic and 1½´
for those firing, with a slope to the sides of from 10 to 15 degrees
from perpendicular, thus lessening the tendency of the walls, whether
revetted or otherwise, to slide in.
The depth of the trenches varies also, for the same reasons that cause
the width to vary. Recesses should also be dug at various and favorable
places for the storing of ammunition and bombs.
When digging entrenchments without regard to concealment, the excavated
soil is first of all thrown to the front or enemy’s side of the trench,
thus temporary cover is obtained. When the entrenchment has reached
the proper depth the artificial raising of the ground is leveled. The
artificially raised portion is known as the parapet. On the completion
of the parapet, the soil is thrown to the rear side of the trench, thus
forming the parados which gives a protection from the rear. It is not a
good policy to excavate in front of the parapet, but to get additional
height and thickness as quickly as possible this is often done. Unless
carefully watched, men will dig this dirt from places as near the
parapet as possible, resulting in the weakening or total undermining
of the parapet or trench wall. The more gradual the forward slope of
the parapet, the more does it approximate as it should to the glacis
of a fort, consequently giving less cover to an attacking enemy. Make
use of the ditch or holes from which the dirt was obtained, as a strong
obstacle immediately in front of your trench, where the enemy at the
last moment may be held up to go under a very severe rifle and bombing
effort. In normal circumstances, by which I mean when not exposed to
an unduly vigorous machine gun or artillery fire, the soil should not
be taken from in front of the trench in the manner described above,
closer than 10 to 15 feet from the actual parapet, unless the holes are
adequately protected by trip wire, as well as barbed wire. Cases have
occurred when valuable information has been obtained by the enemy lying
in holes thus dug and not properly protected.
The parapet should be kept as low as possible and made to blend with
its surroundings as much as possible. This is done by taking great care
to cover any signs which show that fresh work has been done, even to
the extent of actually planting grasses, weeds and roots, such as grow
in the immediate neighborhood, and giving every encouragement to those
that already grow. This greatly hinders the enemy’s artillery, as it
changes positions up and down the line; interfering with and hindering
the observations and accurate ranging by their forward observing
officers, checking charts turned over by relieved batteries.
Bullet-proof nature of a parapet naturally depends on the soil of which
it is composed. Although it is not necessary to memorize the minimum
of safety, you should keep a general rule in your head. The parapet
should not be less than five feet, regardless of the kind of soil. When
the trench has been carefully sited for the actual field of fire from
a ground level, this thickness is best obtained by raising the ground
level artificially as little as possible and getting the necessary
depth by digging, unless prevented by moisture.
Unnecessary casualties are caused by the practice of putting a single
row of sand bags along the top of a parapet for temporary purposes of
concealment, as it gives a faulty idea to the men in the trench as to
the real height of the parapet.
The parados gives protection from the effect of shell fire bursting
behind the trench, and should be made fire-proof as soon as possible,
although it is not necessary unless concealment is possible to level it
down in a similar manner to the parapet. As a matter of fact, it should
be at least a foot higher than the parapet, thus providing a background
for the parapet. It has been known to happen that when the occupants of
a trench have been reached by the enemy they have vacated their trench
and used the parados as a parapet, much to the surprise and disgust of
the enemy. In a high and irregular parados, places could even be found
which when not used steadily provide unexpected and safe observation
and sniping posts, but care must be taken that they are not used too
often.
If a trench were used merely for firing, 4½ feet from bottom of trench
to top of parapet would be a sufficient depth. During attack, however,
when fire from loopholes is too restricted, exposure of head and
shoulders over the parapet becomes necessary, but it is not necessary
to expose men moving along the trench and not actually firing. If the
trench should be 7´ or 8´ deep, you must provide a platform at the
bottom of the front wall 1¼´ wide and 4½´ from the top of the parapet.
This is called a fire-step. The rest of the trench can be deepened
to any desired depth, depending on the energy displayed. If of an
extraordinary depth, steps must be cut to the fire platform.
In a great many different parts of the Western Front, especially
Belgium, it was found that after digging to a depth of one to three
feet water was encountered to such an extent that it became impossible
to dig any sort of a trench which would give adequate protection to the
men involved.
[Illustration: _FIRE TRENCH._
_LINK TRENCH._
_SUPERVISION TRENCH._]
When these conditions are run into, breast work parapets must be
artificially built up above ground level with soil, sods and sandbags,
supported by sandbags, hurdles or close wire netting, revetment and
stakes. The same principles of thickness, depth, width, slopes, and
in fact everything that applies to a dug-in trench, applies to breast
works.
[Illustration: _A--Link Trench, minimum length 5 ft._
_“S” & “T” TRENCH._]
The “T” trench has many more advantages than the few mentioned in the
opening of this chapter. T fire-bays may be single, double or treble
(that is with one, two or three bays). Fire-bays in any length up to
15 feet with 8 feet traverses are for firing purposes only, and the
control trench, sometimes known as the lateral communication trench,
as its name implies, giving lateral communications, is used for that
purpose only. Therefore, the fire-bays and control trenches can be
narrower than trenches which have to be used for both purposes, thus
lessening the amount of repair and revetment work required. And the
intervening ground between these fire-bays gives the same result as
a traverse used in a traversed trench system, and saves the labor of
digging a more intricate system. The control trench gives an officer
or N. C. O. in charge of the T bays a chance to handle his men and
fire in these bays without struggling around innumerable traverses and
wasting time very often when a minute lost or gained means lives lost,
or part of a trench system in the hands of the enemy.
T bays may be sited with due and careful consideration while facing the
enemy in an existing trench system. Thus it gives you the advantage
of being able to take into consideration all the requirements of the
field of fire, control of isolated areas, and the obtaining of maximum
results from enfilade fire. These T trenches may be dug out from the
old system without undue exposure of your men and if distance between
the lines permits, and it is entirely possible to construct a new and
generally more favorable line of trenches within 100 to 200 yards of
the enemy’s trenches. Intervening ground between these T bays must be
completely controlled by entanglements and mobile machine guns, or
automatic rifles, able to operate from different alternating recesses
in the control trench. Fire platforms should be placed in recesses
at intervals in the control trench from which covering fire can be
given. Artillery fire, to damage a T trench, must be very accurate. In
a traversed trench a shell destroys not only lateral communication,
but the defenders as well, whereas with a T shape, both fire-bays and
control trench have to be ranged and hit. The success of the enemy
is entirely local when capturing one of these T-bays, and he may be
shelled by your own artillery without any danger or risks to those
defending their T-bays. Control trenches should be dug first and
zigzagged with the longer stretches facing the enemy. This gives you
another fire-trench as well as a communication trench, and is also
ready for use at any time needed before the T-bay is completed. On the
completion of the T-bay, the corners of the zigzagged trench must be
rounded off to make it easier and quicker for the movement of troops
and carrying of stretchers.
DUGOUTS
It is only under very exceptional circumstances that under-cutting a
trench wall is allowed, and then the shelter should be cut in the rear
wall only. These shelters must be carefully supervised and watched by
the officer, as men are very often careless, with the result that the
shelters are dug in a hurry and poorly. Then it rains, the shelter
falls in, and the men are no more. It should be high enough for a man
to sit up straight, and long enough for him to lie down in, and deep
enough for two men to lie side by side. It should be raised at least
a foot above the floor level in the trench to prevent water from the
trench floor coming in. A shelter smaller than these dimensions is
useless. It has a demoralizing effect, destroying all activity, mental
and physical. These shelters can only be properly made by cutting into
the rear trench wall the necessary depth and length and right to the
top. Then, with any material which is convenient, such as corrugated
iron, brushwood, old rubber sheets, revet the sides and back. A
corrugated iron roof is supported on posts at a depth of about a foot
to a foot and a half below the normal level of the ground. Then, when
possible, cover this with rubber sheets. If not possible to procure
rubber sheets, simply cover with dirt excavated from shelter, taking
care that it does not rise higher than your parados.
[Illustration: FIRE TRENCH, SHOWING ENTRANCE TO SHELTER
The shelter is of use only in a narrow or deep trench. Note that the
floor is above the bottom of the trench.]
A fire-trench, however, is not a proper place for shelters, and they
are generally better as a weather protection than a shell-proof
shelter. Even this should not be favored too much, as it tends to cause
obstruction, delay and inconvenience in the passing of troops. The
real dugouts for the accommodation of men holding a line are generally
behind the fire-trenches in an immediate support line, or as in the
case of T-bays, in the control trench and communication trenches
leading to and from them. These are large dugouts, having a depth of
30 and 40 feet, and in some cases capable of holding 100 to 250 men,
generally having from 5 to 10 exits and entrances. Here the men stay
during bombardments and are generally safe from any caliber shell
which may light on top, unless a half dozen should light in the same
particular spot.
This work is generally of a very skilled and technical kind. Plans,
drawings and labor are supervised by the engineers, expert tunnelers
being used in constructing work, although the infantry supplies working
parties to dispose of the dirt, etc., resulting from these excavations
and to carry the materials and tools needed and required in the
construction.
The design and general scheme of a small dugout which can be made by
the infantry under the supervision of an officer, without the aid of
an engineer, are here given. The dugout should be approximately 6
feet from floor to roof and about 8 feet wide, with an approximate
length of 12 feet, thus allowing men to lie down and yet leave room
for passage through. The width depends upon the number you intend to
have occupy it. Each man requires 18″. Depth to be dug below ground
depends entirely to what extent you may raise the roof upon the ground
without making an unduly exposed hump which will at once tell the enemy
a dugout is there. The thickness of the roof should be approximately
6 feet, constructed with side posts, cross beams, corrugated iron,
waterproof oilcloth, sandbags and soil. Sandbag revetments should be
used in the strengthening of side posts. When possible, although hardly
ever so, walls should be lined with waterproof oilcloth and entrances
so placed that they get as much sun as possible.
[Illustration: _DUG-OUT WITH ROOF REMOVED._
Dimensions variable. Note the wide berms permitting the use of
strong roof supports. A layer of large stones to cause early
shell burst should form part of the roofing.]
Great care and attention must be given to these dugouts, and even
though taking a little longer than seems necessary, care must be taken
to see that they are substantially constructed, otherwise they are in
a constant source of danger of cave-ins during heavy shelling and bad
weather. Not more than 10 men should occupy one of these dugouts. Then,
if accidents happen, your casualties are not so great.
The roof of these dugouts should be prepared in a manner tending
to withstand as high shell shock as possible, and for this purpose
the following table would be of some use, any part of which, or a
combination of all, will give some idea of what is required.
RESISTANCE OF ROOFING MATERIALS
(a) Shrapnel bullets--Stout planks suitably supported and covered with
corrugated iron and 12″ of earth or 3″ of shingle.
(b) Ordinary guns of 3″ caliber--Strong timber supporting 4 ft. of
earth with a top layer of heavy stones or broken bricks to cause early
shell burst.
(c) Field howitzers (of less than 6″ caliber)--12″ logs, supporting 8
ft. of earth with top layer of heavy stones or broken brick and lightly
covered over with some earth.
(d) “Jack Johnsons”--20 ft. of earth or 10 ft. of cement concrete,
reënforced with steel and covered over with a covering of heavy stone
or broken brick.
It is very often the case that there is a line of trenches with very
few dugouts. Those that exist are mainly occupied by first aid stations
with a medical officer in charge, and officers’ headquarters. When such
is the case, very narrow, deep trenches, known as retirement trenches,
are dug roughly from 20 to 50 yards behind the firing line, so that
every one, except those on sentry duty, may retire there during the
heavy shelling. It is very obvious that excellent communication must be
kept up between this trench and the firing line.
DUMPS
Sandbags, corrugated iron, floor boards, ladders, pails, brushes,
rubber boots, periscopes, barbed wire, etc., are what are known as
“trench stores.” These are generally brought up by carrying parties
during the night and taken to some convenient spot picked out by
whosoever may be commanding that particular section of trench, ready
for distribution in the morning. This place is known as a “trench
dump.” Here every morning each junior officer goes to his company
commander with a request for his stores for the day. When this has
been handed in and approved by his company commander, he then has a
party detailed to go and collect his stores. These are again placed
in his particular little sector of the lines and he receipts for
their care and proper use; all stores not used are turned over to
the relieving troops and a receipt taken for same. These dumps must
be made in a central location, both as regards the company dump
and the platoon. The company dump is not a permanent home for the
stores or utensils brought up, but is merely what might be called the
distributing center. When a company commander turns over his trench
stores and utensils to the relieving commander, the fact that he has
all his stores and utensils in the company dump does not show merit,
but merely inefficiency, that the distribution, which should have taken
place, has not been carried out, and, therefore, that some of the men
under his command probably have not the required tools to work with or
the material that is necessary to the small units to carry on their
daily lives. Stores should not remain in their center dumps. But each
platoon commander should know exactly how much he has in hand, and how
much he needs. It is also plainly evident that in a scattering of dumps
in this manner, any captured by the enemy do not constitute a “knock
out” as far as the trench stores are concerned.
LATRINES
The cleanliness of the trenches and latrines requires the closest
supervision of all officers and non-commissioned officers. The bucket
system of latrines is entirely unsatisfactory. The ground where the
buckets are in use becomes unsanitary, and so does the ground in
which the contents are buried. Double labor and carriage is involved,
and as often as not a polluted soil is sooner or later to be found
in the line of a proposed communication trench. The method used in
the French armies is very good and by far the cleanest. It involves
no unpleasant labor and is satisfactory. A pit about 12 feet deep, 3
feet wide and 12 feet long is dug in some place which is fairly easy
to get at by those who are to use it. Generally thirty to forty feet
behind the fire-trenches and off one of the communication trenches.
The pit is boarded over, the boards being laid across the width, that
is from front to rear; every other board space being omitted. A pail
of disinfectant is kept standing nearby, and the deeper the pit is,
the better and longer it will remain in use, but should be filled
in when contents are within 6 feet of the top. This makes subsequent
unpleasantness very unlikely. Care must be taken that men using these
places have some protection from stray shells, and are out of sight of
the enemy.
When possible, there should be a refuse pail for every section of men,
and care should be taken to impress on the men that they must throw
in all tea leaves, dregs, all scraps of food, and refuse in general,
and should be covered over with disinfectant. If this is not done,
thousands of flies and insects are attracted, with the inevitable rats,
and disease and unsanitary conditions will follow. Tin cans, etc.,
should under no circumstances be thrown over the parapets as the same
results will occur there.
REVETMENTS
When fire trenches are to be occupied for any length of time it is
necessary to revet them. By that I mean the walls, and especially
front walls, have to be faced or strengthened by sand bags, boards,
corrugated iron or other material that is needed. This work to be of
any use at all must have solid foundations and be thorough from top to
bottom. Careless revetment work is of no use and a source of endless
labor and trouble. All such work should be supervised by officers or
N. C. O.’s who have a thorough understanding of such things, and they
will be amply repaid if they take an active part in the work with their
own hands. There are several forms of revetment, according to the
materials available and the conditions of the walls to be revetted, but
the usual materials are the sandbags, corrugated iron, stakes, boards,
wire netting, etc., and these can be used either separately or in a
combination. All these materials are generally kept in engineer dumps,
some little way behind the firing line. Requisitions are made during
the day by the officer commanding the sector of trench which requires
revetting, and at night the men are detailed in carrying parties to go
down to the engineer dumps and carry these things up for work the next
day.
SANDBAGS. Sandbags are usually available in large quantities, but it is
well to remember that generally only half the number indented for reach
the indentor. The rest generally go around the men’s feet and legs to
keep them warm at night, and very often are used as a sort of mattress
in the dugouts. This should not be allowed as it creates a tremendous
wastage. The sandbags should only be about three-quarters filled, thus
allowing for the choke or neck end, after tied, being turned under the
back when laid in position. This also gives something to catch hold of
when laying and brings the weight to something manageable, about sixty
pounds. A bag three-quarters filled measures approximately 20″ x 10″ x
5″. Laid sand bags are called headers, when laid with bottom of the bag
facing the center of the trench, and stretchers, if laid with the side
facing the trench as per sketch. The neck end should always be tucked
well in the bag in the case of the stretcher; the side seam, which is a
weak spot in the sandbag, should be kept from exposure, that is, should
be turned from the center of the trench.
When the front wall of a trench is to be revetted and only sandbags are
available, the wall should first be cut to a slope of from 10 to 15
degrees from the perpendicular, and the loose soil obtained, if dry,
placed in the sandbags. When there is an unrevetted fire platform,
this should be also cut away and put, if dry, in the sand bags. A
bed should then be dug about 6 inches into the solid bottom of the
trench (disregarding the soft mud which for foundation purposes is
of no use) and sloping down into the parapet at right angles to the
slope of the front wall. Into this bed place a row of headers. On this
row place a double row of stretchers. Joints must always be the same
manner as brick-laying; that is, care taken that the joint where the
ends of the stretchers meet does not come immediately over the joint
between the headers and the lower row. Sand bags should now be beaten
down flat, generally with a wooden mallet provided for this purpose;
then alternate rows of headers and stretchers laid; each layer being
flattened out with the mallet until the top of the parapet is reached.
The top layer should always come out as headers.
[Illustration: Headers, Stretchers, Headers]
Twenty-five headers or twelve stretchers, or sixteen mixed, is the
average required for revetting every superficial yard of trench.
The slope of a front trench wall, even when from 10 to 15 degrees from
perpendicular, is apt gradually to assume the perpendicular, and then
fall in, owing to the sinking of the trench bottom or the actual thrust
of the earth in front. This can, however, be checked by using 6´ to
8´ stakes driven well into the front wall foundation, and at the same
angle as the front wall. Then, wiring the head of these stakes to what
is known as an anchor-stake driven about 10´ into the ground in front
of the trench.
Sandbags come in bales of 250, which are again divided into bundles of
50 each. On a carrying party it is an average rule that each man carry
100 sand bags.
CORRUGATED IRON. Generally, when lengths of corrugated iron and plenty
of floor boards and stakes are available, this material is used for
revetting the lower half of a trench wall, as it removes a great many
difficulties, such as looking over substantial foundations for sandbag
revetments. It makes it unnecessary to fill sandbags, etc., thus saving
a great amount of time and labor. In revetting with corrugated iron and
stakes or hurdles, cut the slope or wall from 10 to 15 degrees from the
perpendicular, putting the soil in the sandbags and leaving it in some
handy place for any future use. Then, drive 6´ to 8´ stakes well into
the trench foundation and approximately 4´ apart, thus giving adequate
protection to each piece of corrugated, having the stakes at an angle
of 15 degrees at least, from the perpendicular, and 6″ or 8″ away from
the trench wall. Then, slide the corrugated, hurdles, or boards on
their sides down behind the stakes, overlapping slightly the ends and
ramming them well down into the mud or soil in the bottom, and filling
in the space behind with soil.
The bottom third or half of the front wall is thus substantially,
easily and quickly revetted, and the upper half or remainder is
generally revetted with the sandbags, a bed being dug so that the
first layer of headers is about half its depth below the top of the
corrugated. If stakes shorter than 6´ or 8´ have been used in the
revetting, half should be cut off to where the sandbag revetting
commences and wired to anchor stakes, driven into the parapet end of
the bed, and not wired over the top of the parapet, as it tends to
gradually pull them upwards. Then cover this wiring with your first
layer of headers. When hurdles or floorboards are used instead of
corrugated iron, empty sandbags or similar material must be hung behind
them to prevent the soil crumbling through and thus weakening the
foundation of the sandbag revetments. Corrugated should not be used
for revetting the front wall higher than 2´, which is the width of
one sheet, as the supply is generally limited and can be put to more
valuable use as dealt with later.
Corrugated iron comes in bundles of about 24 sheets to the bundle,
averaging 6´ by 3´. Two sheets is the average load for any one man in a
carrying party.
A front wall constructed in the manner shown, if prompt and immediate
attention always be given to repair if damage is done, will give very
little bother. It is the usual custom to construct your fire platform
after this revetting work has been done.
A trench should be dug no deeper than will afford protection to the
firer, a deeper passageway necessitating a fire platform, a subsequent
work, and by first revetting the whole front wall from bottom to top
then adding the fire platform, each gets the benefit of the foundation
of the other. Until this fire platform is constructed, emergency
methods may be used and improvised in a moment with ammunition boxes,
loose sandbags and the various other junk which accumulates in a trench.
FIRE PLATFORMS. Now that the front wall has been revetted, either with
corrugated or sandbags, the construction of the fire platform should be
at once started. To start this, short stakes should be driven well into
the trench bottom about 36″ from the front wall and parallel to the
slope of the front wall, averaging from 2´ to 3´ apart and generally
as substantial as the large revetment stakes, although this is not of
absolute necessity.
When brushwood is procurable, it should be used as a foundation,
putting it in after the short stakes are driven and ramming it down
behind them. This gives you as nearly as possible a dry and compact
foundation for your first row of headers. Then this may be covered with
another lot of brushwood, and that again by a row of headers, and from
then the layer should be alternate headers and stretchers. Sand bags do
not offer a good platform after a heavy rain, as they become wet and
slippery and the material quickly rots, then they break open and the
top of your fire platform is gone. To avoid this, it is necessary to
use whatever material may be at hand in the covering of the top layer.
One good way of providing this top covering when the material is
procurable, is a wire netting used in a double thickness. It should
be placed behind and up against the stakes before the foundation is
laid. Then when the fire platform is built to its proper height, bend
the wire from the top of the fire platform and fasten it down on the
sides by whatever means are handy. Using this double wire netting
makes it possible to use brick and all sorts of general trash in the
construction of the fire platform and gives a very good dry footing.
When doing that the face of your platform should be either corrugated
sheets or boards.
Very often what are known as sentry-boards, or small floor boards about
36″ square and with additional cross pieces underneath, giving them
a height of about a foot, thus raising them well out of the mud, are
used, and are very handy before a fire platform is made, and in some
cases have to be used for small men after the fire platform is made.
TRAVERSES
All the walls of the traverses must also be revetted, generally with
the sandbags and in exactly the same manner as the front walls of a
fire-bay, care being taken to keep it well sloped. This leads to a
lessening of protection afforded the occupants by making a greater
width at the top of the trench, but it is absolutely necessary unless
you wish your whole traverse to gradually fall in, when you are in a
position of having no protection at all. The top of the traverse may be
and is often several feet higher than the parapet, if the fire-bay it
protects is exposed to enfilade fire from the enemy trench at a higher
level. But when this is not the case, the traverse should not be higher
than the parapet or parados, and should slope down towards the enemy to
give the appearance of being merely a continuation of the parapet.
The traverse should never be less than 9´ wide, allowing 2´ for a
sentry box, although this sentry box is no longer generally in use.
What are known as overhead traverses are made generally in a
communication trench leading up to the front line, and which in certain
parts the enemy are able to look into. These overhead traverses give
to this particular place the protection which is necessary. They are
quickly and easily made by placing corrugated iron, logs or strong
branches, or floor boards, across the top of the trench and putting
sand bags on the top of these. When the trench walls are weak, or even
on general principles, the sides supporting this overhead traverse
should be revetted with sandbags.
The sentry boxes, although not in general use now, are described, more
for general information than anything else. They are dug or recessed in
the traverse at either end of the fire-bay and must have an observation
slit in the parapet for use by day, but no loophole facing the enemy,
as regardless of the care and caution used in the construction of these
loopholes, they will sooner or later, generally sooner, be observed by
the enemy and the sentry box made useless.
During an attack this sentry box is never used, except for stores or
the placing of wounded, as there will always be plenty of room for the
late occupant in the fire-bay itself. Sometimes, when energy and time
permit, an enfilade fire loophole is made through the traverse and
facing the next fire-bay, but this has as much value for making easy
verbal communication from one fire-bay to another as it has to the
checking of attacking forces.
LISTENING POSTS
As before mentioned, in the space between the front lines of the
opposing armies, which is known as No Man’s Land, there are sometimes
large and sometimes small areas of ground, ditches, streams, etc.,
which cannot be satisfactorily watched from a fire trench immediately
facing them, owing to the lay of the land, hedges, old excavations,
buildings, etc. This is the case in a great many instances regardless
of the careful thought and the amount of time spent in siting a
fire-trench, as the siting of all trenches is largely subsidized by the
tactical position of the flank trenches. Very often a line of trenches
is taken up under stress of circumstances that do not permit of the
obeying of the rules and standards set for an ideal fire-trench.
The control of these areas is essential to prevent small surprise
attacks, cutting-out parties and raids. During the day they are very
often observable from a flank trench or higher observation ground in
the rear, but at night this is not possible; so that listening or
observation posts are gradually sited in front of the fire trench
with due consideration to the situation in that immediate vicinity. A
ruined shed, shack, cart, or any other thing of a similar character
lying in No Man’s Land is very useful for these purposes if it can be
reached before the enemy reach it with the same purpose in mind. This
cannot be used very long, as its purpose is too obvious and peace and
quietness will not last long, but it will do until a more satisfactory
arrangement can be made.
The listening post is often dug just inside the outer fringe of your
own barbed wire entanglements, and is just large enough to allow two
men to stand in unobserved. It should be reached by a very narrow,
irregular trench running out from a fire-bay, where it is fairly
easy to secure the maximum amount of concealment necessary to give
protection. The soil excavated from these places must not be thrown
out, but placed in sand bags and taken into the trench and used there.
It is always best and requires very little more labor, and gives the
maximum amount of protection to your listening post if communication to
it be made through a tunnel.
These things are bound to be discovered within a certain amount of
time, and when you know the position of your listening post has been
found by the enemy, which you will know very quickly, owing to the
amount of bombs and rifle fire it will receive for one or two nights,
until you can dig another one, it is a safe thing to build up a small
parapet, taking it down every morning before dawn. It then becomes
necessary to dig a new post, and this can be generally done by leading
off from your old communication trench to some more favorable spot.
When the new post is ready for occupancy, the old one should be filled
in with barbed wire, or completely filled in again with dirt, and the
sandbag parapet left to mislead as long as possible.
The first duty of a listening post is to listen and report. Most of the
work is done at night, and no firing or sniping must be allowed from it
during the day. Patrols generally come out via one listening post and
return by another, so that all listening posts must be warned of the
trench by which the patrol will come out and the approximate hour of
departure and return. Patrols should never be sent out without definite
orders as to what is required, and especially as to the listening post
they leave and return by. Listening posts should fire without challenge
at any one who approaches within sight, whether friend or enemy, unless
it has been warned that a friendly patrol is out, in which event
signals should be pre-arranged. Then the listening post will use the
greatest caution and should challenge audibly when the patrol is close,
and unless immediately satisfied, fire. Listening posts are connected
with the fire trench by a cord or wire, and a simple code of tugs is
arranged, or a bell fastened to the fire trench end for alarm in case
of emergency, and here a sentry always stands to get any signals that
may come from the listening post.
If a listening post has not been warned that a friendly patrol is out
and fires on it without challenge, the L. P. is absolved from all blame.
When a hedge or ditch, which might easily provide cover to the enemy,
is running parallel with the firing trench, it must be controlled at
night by a machine or Lewis gun which is able to enfilade a frontal
advance over open ground leading to it. If, as is often the case, the
parallel hedge or ditch is easily approached along either hedges or
ditches running at right angles to it, these angles must be protected
by machine or Lewis gun firing down them.
When hedges or ditches running at right angles from the firing line
and leading towards the enemy are in a sector of line, they should be
protected from dusk to dawn by one or two men, generally only armed
with bombs to protect against surprise, and great care must be taken
that no more signs than possible are left to the occupancy of this
position over night.
OBSERVATION POSTS
LOOPHOLES FOR FIRING. During an attack, firing is never possible
through loopholes as it is too restricted to be of any value. All the
firing then is done over the parapet. The difficulty of constructing
new observation posts which are effectual and inconspicuous for any
length of time has resulted in their not being made in a parapet,
where, when located by the enemy, they are as often as not a source of
danger. Moreover, promiscuous firing through loopholes by inefficient
riflemen is of no value. Sniping is under the control and supervision
of a sniping officer, and loopholes should only be used by men
appointed by that officer. They are not used at night and should be
only used during the day for enfilade fire, and be placed in the
parapet as low down as is consistent with line of site. A piece of
cloth or empty sandbag should be hung from the rear of the loophole,
so that when the hole is not obstructed by the fire, no light can
show through. No shots should be fired from those loopholes, except
at a definite target, and ranges of targets or spots where targets
may possibly appear, should be ascertained in advance, and necessary
exposed movement, such as withdrawal of rifle, must be very slow
and gradual. With care, and when only used by a skilled rifleman, a
loophole will be of value for probably two weeks and good results
obtained, but by a careless man the value of a loophole will not last a
day and very likely result in casualties not only to the man shooting,
but to others as well.
In the area from 20 to 100 yards behind the fire trench, there
sometimes is, although very seldom, ground much higher than the actual
fire trench, so that it is safe to allow even hastily trained men
to use it for firing over the heads of the main front line trench,
although it has happened that men in such a position have fired into
their front line, thinking it the enemy line. This ground is generally
used by building what are known as covering fire trenches. These to be
of any value, should not be more than 20 yards behind the front line,
as farther forward than 20 yards they become affected by artillery
fire directed at the fire trenches; and farther back than 100 yards
the covering fire, unless in the hands of very skilled and efficient
riflemen, becomes very dangerous to the men in the front line.
SUPPORT TRENCHES AND SUPPORT DUGOUTS
A support trench is usually within 30 to 300 yards of a fire trench,
and may serve the purposes of covering fire trenches by skilled
riflemen or an indirect machine gun fire, but their main purpose is
to shelter troops from observation and shell fire, and thus their
main characteristics become the size and strength of ample dugouts.
Troops in the support dugouts are at hand for three purposes: Firstly,
replacing of casualties occurring in the fire trenches during normal
times or a hostile attack. Secondly, holding the support trenches in
case the fire trenches are taken by the enemy. Thirdly, in the event of
an attack on the enemy’s trenches, leading the attack by moving forward
over the heads of the occupants of the fire trench, or if the latter
are leading the attack, to occupy at once the fire trench when vacated.
For this reason it is of vast importance that there are accessible and
commodious support dugouts and communications between the immediate
support trenches and front line. If this is so there will be less
chance of disasters to supports and reserves coming up to make good a
successful attack. There must be support dugouts even in the event of
there being no support trenches, and this is very often possible owing
to the lay of the land. The strength and size of these dugouts entirely
depend on tactical considerations and local conditions, which are
generally decided by the staff.
SUPPORT POINTS
These forts or strong points, as they are sometimes called, usually
round or square, but which may be any shape best suited to the
condition of the country in which they are placed, are generally from
100 to 300 yards behind the fire-trenches and supplementary to the
support trenches. Each of these strong points contains a permanent
garrison of firing troops, strongly protected with barbed wiring
and sandbag revetments, and well supplied with ammunition, food and
water, to enable them to withstand heavy attacks. During an attack
they are used to give overhead covering fire, and for the control of
ammunition and other supplies to be sent on to the firing line. It is a
general rule that if the enemy take a fire line the garrison of these
supporting points must hold out and remain a thorn in the enemy’s side
until the last man of the garrison is killed.
RESERVE DUGOUTS
These dugouts protect the local reserves from which supports are
supplied and are used for purposes similar to those for which the
immediate support dugouts are employed, but on a great deal larger
scale. These dugouts are generally near battalion headquarters and from
500 to 1,500 yards behind the firing line. The chief considerations
in siting the positions of these dugouts are three: First: facilities
for rapid and easy transit to the support and fire-trenches; second:
concealment; third: comfort. Comfort should be secondary to the other
conditions affecting the siting of the system.
SECOND LINE
This comprises the line of fire-trenches, with covering fire-trenches,
support trenches, support dugouts and reserve dugouts (in other words,
it is an exact duplication of the front line system), far enough behind
the front line that in the event of the first system being taken,
the second line is ready to be taken up by the troops driven out of
the front line, and receive the support of troops lying in brigade or
divisional reserve. The distance of the second line behind the first
is roughly a mile, and while the first line is held, operations of the
second often provide useful accommodation for the machine guns and
artillery, both for firing purposes, observation and shelter.
The time available for siting and constructing second line system, and
the freedom from all disturbances which bother the front line system,
should result in its being impregnable. It is an ideal system provided
those responsible for its siting and construction are thoroughly and
practically experienced with first line conditions and profit by that
experience and former mistakes.
COMMUNICATION TRENCHES
When siting communication trenches, two considerations come into
conflict with one another; the desire for protection, and the necessity
of rapid and easy transit. It is obvious that a C. T. is of vital
importance to the firing line in the getting up of supporting troops,
ammunition and stores rapidly and without undue fatigue. It is also
obvious that it must give as much protection as possible to the troops
using the C. T., but it must be recognized that the protection given
must not interfere with rapid transit by making the C. T. too narrow.
It must also be kept in mind that rapid transit in itself gives a
certain amount of protection for the simple reason that the easier and
quicker the transit, the less time are troops delayed in the C. T.’s in
which protection is required, and if troops can cover the danger area
in 10 minutes, they are plainly in danger for a less period than if it
took 30 minutes to struggle over that same area. This rapid transit,
only obtained by a dangerously wide communication trench from support
or reserve lines and from dugouts, also makes it possible for less
troops to be regularly on duty in the fire-trenches, which are always
uncomfortable and dangerous, especially during a bombardment, and it
also enables supports and reserves to be rushed up quickly when the
occasion demands.
It can be plainly seen now that a compromise must be effected between
claims of protection and rapid transit, so that the size and shape of
the C. T.’s will vary according to their distance from a danger area.
Generally speaking, the nearer to danger, the more must the claims of
rapid transit give way to those of protection.
Disregarding for the time being the claims of protection and only
considering rapid transit, there are these things to be considered:
First, that a C. T. be as short as possible, making use of contours,
sunken roads and other natural features to avoid digging as much as
possible. Second, that a C. T. be as straight as possible, which not
only shortens the distance but avoids turns and corners which interfere
with speed and which require renewed effort at every turn. These sharp
corners and turns must always be avoided. This can be done without
weakening a trench or increasing the risk, and every effort should be
made to save troops carrying full equipment, stores, ammunition, or
rations from unnecessary tiring, hindrances, and difficulties, such
as sharp corners and turns. Third, the C. T. J.’s must be as level as
possible, as they are generally slippery, and inclines or declines
should be avoided as they very often cause accidents. A longer C. T.
following around natural contours is frequently more advantageous for
this reason than a straight one over a hill, which it is only possible
to make level by an amount of digging out of proportion to the result
gained. The C. T. must be wide enough for requirements. These differ
according (a) to the proximity of C. T. to the fire-trenches, (b) to
the number of C. T.’s available, and (c) to the use for which a C. T.
is required, i. e., whether a double C. T. (for both up and down
traffic) or a single C. T. (for traffic in one direction only).
When a C. T. is close to the fire-trench, troops moving into it
are practically themselves in the fire-trench and as each group
has probably to get to a different part of that fire-trench, all
necessary traffic up and down the fire-trench and disturbance of the
men occupying it must be avoided. Rapid transit can advantageously be
obtained by other means than the width of the C. T.; by dividing the
single C. T. at some point from 30 to 60 yards in rear of the actual
fire-trench into a number of small narrow C. T.’s, each leading to a
group of 3 to 6 fire-bays, and these may again be divided into those
for up and those for down traffic.
This system requires a fair amount of thinking out and all the trenches
should be plainly marked and named. These names are placed on notice
boards at the different junctions having the proper indications and
rules directing the use of up and down traffic. This is and should be
rigidly enforced during both quiet and active periods, but takes on a
much greater importance during active periods.
The width of these single C. T.’s running close to the fire-trenches
should be enough to allow a man carrying full equipment, stores, or
rations to pass along easily and without bumping the sides with his
equipment or burden; approximately two feet at the bottom with ample
room at all corners. The width of a single C. T. for down traffic
only should be wide enough to allow for passage of a laden stretcher,
especially at the corners, as a stretcher is a very clumsy thing to
get around these corners and often the delay caused has very serious
consequences.
As a C. T. leaving a fire-trench gets farther away, the width should
be as soon as possible such as will allow two men to pass one another
fully equipped without jostling or scraping the sides of the trench, or
approximately 4 ft. at the bottom. This width with recesses described
later allows rapid transit for troops passing each other in quiet
parties and allowing a much greater safety in an emergency when there
is no down traffic.
The front is always referred to as “up.”
Another advantage to be gained in the width of the C. T. is in the
fact that it is much easier to keep dry and usable. It permits laying
of regulation floor boards, allowing enough room on each side of them
for the purpose of drainage, and is a means of preventing falling
soil from covering the floor boards. Water will not drain off or
through soil which is continually trampled on and has become sodden
or irregular, and unless the floor boards are kept free from soil,
they soon become useless, crooked and immovable. The width of these
trenches allows the wind and sun to reach the bottom of the trench,
thus helping a great deal in keeping it dry. There is no such thing
as a communication trench 18 inches wide at the bottom and 24 inches
wide at the top; diggings of these dimensions are nothing more than
drains which in an emergency only are struggled through when passing
in the open is still more impossible, and they should not be given any
consideration whatever as a C. T.
The features required in a communication trench, regardless of the
claims of rapid transit and only considering protection, are:
(First) Frequent traverses or turnings to avoid the effect of enfilade
fire, to localize the effect of a bursting shell or bomb, to make
difficult a hostile advance down the C. T. and to enable bomb parties
to resist more easily their advance.
(Second) A trench that is sufficiently narrow will localize the effect
of a bursting shell or bomb and minimize the effectiveness of hostile
fire, which must have a high degree of accuracy to be effective. But
the quicker over the ground the shorter the period of danger, and shell
fire of any degree of accuracy will substantially narrow one of these
narrower trenches, damaging the walls and causing casualties and other
obstructions which will render passage impossible with either one or
two results. Delay caused at a critical moment, or the occupants trying
to obtain a passage up the trench in order to take any part in the
fighting, would have to come out into the open sooner than necessary.
The shelling of the C. T.’s usually is heavier for perfectly obvious
reasons during an attack and when rapid transit through them is of the
utmost importance. A narrow trench generally takes as long to dig as
one of the wider type, owing to the restricted area in which to work.
(Third) If invisibility be possible, it is an excellent feature, but
in nine hundred and ninety-nine cases out of a thousand it is hardly
possible. An observed C. T. indicates the position and direction of
supports, stores, reserves, dugouts, etc. This fault can be corrected
to a certain extent by the careful use of the contours, dead ground,
sunken roads, and all natural features, such as woods and hedges.
Artificial cover may and does assist concealment, but sooner or later
hostile aerial observation and photographs disclose the position of
more easily concealed things than an excavated C. T. It is frequently
the shadow at the bottom of a trench which gives its position away
to aircraft, and the narrower the trench, the more prominent is the
shadow. The soil, which is generally a different color from the surface
soil, must be thrown up on either side as time does not allow it being
carried away. Unless in a place of artificial cover through the length
of the C. T., it is usually necessary to admit the impossibility of
concealment and utilize time more profitably by taking protective
measures.
Rapid transit to a fire-trench is of greater importance than rapid
transit from a fire-trench, and the importance of protection is
greater as the fire-trench and its dangers are approached. Methods
of construction should be based on this idea and the arguments given
above.
SKETCH OF TRENCH SYSTEM
This sketch shows a double-traffic communication trench leading (5 ft.
wide) from reserves and H. Q. to a loopholed island-traverse about 30
yards behind the support line. At this island-traverse, single-traffic
C. T. branches off to various sectors of the support line; the main
C. T. leading on (from 3 to 4 feet wide) uninterrupted through the
support line to loopholed island-traverse “E,” about 30 yards behind
the firing line. At this island-traverse the main C. T. breaks off into
single-traffic C. T. 3 feet wide. Each leads to various sectors of the
firing line.
[Illustration: SECTION I
SKETCH OF TRENCH SYSTEM]
SECTION I. C. T. should start behind one of the fire-trench traverses
and not from a fire-bay. Every yard should be contestable for
approximately the first 15 to 20 yards. This can be effected, and at
the same time the effect of hostile artillery and rifle fire and bombs
localized, by a series of traverses 9 feet square, the trench being
approximately 7 feet deep and 2 feet wide at the bottom. Cut into the
rear of a few of these traverses is a narrow recess through which one
of the defending bombing party may take up a position in the center
of the traverse and fire, kneeling or standing, through a loophole at
the advancing enemy. The recess gives him ample protection, including
head cover, and is so cut that the entrance is out of alignment with
the trench behind him and he will be unaffected by a bomb exploding
there. At the same time he may work with, and direct, the bombers
behind him who are bombing over the traverse, and if it becomes
necessary, they can also take cover in the entrance to the recess. The
loophole should not be placed so high that it becomes possible for the
enemy to come forward under it.
The most dutiable arms for the members of the defending bombing party
detailed for this traverse work are what are known as “close-contact
weapons,” generally including revolvers, bombs, trench knives, and very
often a bayonet carried by pushing it down in the puttee.
[Illustration: SECTION II
SKETCH OF TRENCH SYSTEM]