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Title: Use of Mines in Trench Warfare - From the French School of St. Cyr
Author: Anonymous
Language: English
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*** Start of this LibraryBlog Digital Book "Use of Mines in Trench Warfare - From the French School of St. Cyr" ***


  Italic text is denoted by _underscores_.

  A superscript is denoted by ^x or ^{xx}, for example G^2 or 1^{st}.

  Some minor changes to the text are noted at the end of the book.




  (From the French School of St. Cyr)


  JULY, 1917

  [Illustration: (Seal of the 'UNITED STATES OF AMERICA WAR OFFICE')]



  Document No. 635.

  _Office of The Adjutant General._

  WASHINGTON, _July 23, 1917_.

The following notes on Use of Mines in Trench Warfare are published
for the Information of all concerned.

  [062.1, A. G. O.]


  _Major General, Acting Chief of Staff_.

  H. P. McCAIN,
  _The Adjutant General_.

  _Washington, June 19, 1917_.

_To all officers of the Army_:

You are advised that this and all subsequent documents of a similar
character which may be furnished to you from this office are to be
regarded as strictly confidential. They are to be kept at all times
in your personal possession, and are not to be copied, nor are
any parts of their contents to be communicated either directly or
indirectly to the press, nor to any person not in the military or
naval service of the United States. In Europe these documents are not
to be carried into the front-line trenches, nor farther to the front
than the usual post of the officers to whom issued.

Strict compliance with this injunction is enjoined upon every officer
into whose hands any of these confidential documents may come.


  H. P. McCAIN,
  _The Adjutant General_.



  Use of mines                                             5

  Specially menaced points                                 5

  Surface observations                                     5

  Indications revealing enemy galleries                    6

      Listening for underground noise                      6

      Position of listening posts                          6

      Hours and precautions                                7

      What is heard                                        7

      Distance at which noise can be heard                 7

      Direction from which noise comes                     8

  Useful information on mines                              8

      Defensive systems                                    8

      Interval between galleries                           8

      Start, depth, and progress of work                   9

      Barrage trench for miners                            9

      Camouflet                                            9

      Offensive galleries                                 10

      Superimposed galleries                              10

      Mine chamber                                        11

      Launching an attack                                 11

      Craters                                             11

      Craters to be occupied                              11

      Craters that the enemy occupies                     12

      Craters not occupied                                12

      Diagrams                                 9, 10, 12, 13


[From the French St. Cyr School.]

(Secret and Confidential. For Official Use Only. Not to be Taken into
First-Line Trenches.)


In sectors where the distance between the two lines is below 150
meters, mine warfare must be used. When the trenches are farther
apart, underground warfare is seldom employed. In special cases,
however, when there are strong ventilators and the line is stable
enough to permit of it, advance may be made underground.


The most vulnerable points evidently are the following: The outposts
in advance of the line, machine-gun positions approximately located
by the enemy, and the junction points of the communicating trenches
with the first line.


Underground activity, either offensive or defensive, is first
observed from those points in our lines nearest to it. All enemy
trenches facing a salient of our lines will be the object of
particular attention and closest daily observation. This observation
of the first-line trenches should disclose the presence of enemy
underground works and their approximate location.

One of the difficult questions in mining is the removal of the
earth. Expert miners sometimes remove the earth as far as 100 to 200
meters from the entrance to the gallery. They throw it on old ruined
shelters, in shell holes, on the reverse of the trenches. But these
precautions are not always rigidly observed. When the noncommissioned
officer is absent, or the enemy bombards a little strongly, some one
in the working party not wanting to work overtime throws several
clods of earth on the parapet.


Freshly placed earth coming from underground is white and less dull
in color than that of the parapets, which have been washed by the
rain and blackened by explosives. The difference in color for the
first day or so is striking. In chalk, large white spots are seen on
the reverse of the German trench, daily growing larger. Without doubt
they are working near by, and should be watched.

A communication trench comes out at a salient, and runs back from 150
to 200 meters. Patches of chalk, freshly moved and increasing daily,
are observed. These are indications of underground work starting from
the salient.

Four or five meters of enemy trench without loopholes, but with
loopholes close together to the left and right, may mark a gallery

A miner's working relief reaches the gallery, each man carrying a
piece of the frame or a lining plank over his shoulder, the ends of
which can be seen over the parapet or through the loopholes. These
are indications of a gallery position, especially if the men all move
in the same direction and are lost to view at the same place.

From a raised point on the second or third line we see, with field
glasses, an abnormal accumulation of sandbags in a well-known area.
These sacks may indicate an underground gallery.

Patrols sent out in front of the enemy trenches sometimes bring back
valuable information. They may hear the rumble of ventilators, the
noise of a truck moving on the rails, men working near a gallery
entrance, etc.

The enemy fire with heavy calibers on portions of the first line.
Often the same corner is bombarded. This may indicate that the enemy
artillery is seeking to facilitate the miner's work by overthrowing
the entrances to troublesome galleries in the trench attacked.

_Listening for underground noise._--The observation of hostile
trenches may give indications which will limit the zone necessary to
be watched; but for accurate results we must listen for underground

_Positions of listening posts._--The listening post is placed at the
head of a gallery, in an angle of a gallery, in a deep dug-out, in a
niche under the parapet, or on the bottom of the trench. The points
nearest to the enemy trench are selected for the listening posts.
Below the outposts there is always a niche, allowing a man to place
his ear to the ground (hence the name listening posts).

_Hours and precautions._--The most favorable hours are morning about
4 or 5 o'clock, at 2 p. m., and at midnight. All the occupants of
that part of the trench must keep still, and all work in the trench
and the mine must cease for a given time.

_What is heard._--The inexperienced ear hears too many things, and is
easily mistaken in the noises heard. A relief passing in the enemy
trench or in his own trench at 40 meters sounds strangely like the
noise of a pick. A man hitting a ground sill or striking it with his
heel gives the idea that work is being done. The impact of bullets on
the parapet at night, when a fusillade is uninterrupted, also gives
the idea of underground work. A man filing a fuse at the foot of his
loophole suggests the presence of an enemy revolving borer. A man who
snores beside the gallery entrance imitates the noise of a ventilator
and may be mistaken for it.

However, to even a partially trained ear the noise of the pickax is
characteristic. It is not a harsh sound, like that of a heel striking
on chalk ground, nor is it like the shock of bullets piercing the
parapet. It is a low, rhythmic sound, with regular cadence. In a
gallery the miner works kneeling. When he has struck five or six
blows with the pickax, he takes a breath. He repeats this process
about 12 times. He stops two or three minutes, and the second miner
clears away the earth and fills the truck with sacks. The first miner
resumes his work. It is easy to distinguish this regular cadence
peculiar to the miner.

In an infantry company there are always several miners by occupation,
or several men familiar with engineering. These men are selected
specially for the listening service. They can give accurate
information to the officers and noncommissioned officers of a sapper
company. It is also a good thing for a platoon commander to descend
into a gallery and train his ear by exchanging pickax signals with
the miner in the adjoining gallery.

_Distance at which noise can be heard._--The following indications
help in determining the distance of underground work:

Four men work in a gallery. They start the work, then stop. The ear
is placed against the side of the wall, the other ear being covered
by the hand. If the work is heard under these conditions, it is at a
distance of 25 to 30 meters.

If all noise is avoided, and the work is heard without placing the
ear against the wall, the distance is 12 to 15 meters.

If there is talking or working going on, and still the underground
work is heard in spite of it, the distance is 8 to 10 meters.

At six meters a man can hear all the sounds of the pickax, the chalk
crumbling, the pieces rolling down on one another, the sliding and
stacking of cases. These noises sound as if they were immediately

At four meters a man can hear talking, the scraping of buttons
against the wall, the miner turning around.

The humming of a ventilator can be heard at 40 meters without taking
precautions to hear it.

An automatic borer can be heard all through the sector.

_Directions from which noise comes._--It is easier to determine the
direction of noise than the distance. There is always a chance of
making observations in the galleries--one on the right, the other on
the left of the noise. The exact location of the enemy underground
work can be determined by intersections.

The engineer companies have an apparatus for intensifying the sound
(strong microphones). They reinforce the sound when the apparatus is
in the direction of the source of the sound. Their greatest defect is
that they magnify sound too much and too many things are heard. Why
hear for a distance of 100 meters when the enemy trench is only 40
meters away? Everything is heard in a mine gallery. It is difficult
to distinguish among the many noises that of the enemy miner's pick.
The ear is amply sufficient.

The beginner has a tendency to exaggerate the proximity of sounds.
He thinks he is close to the enemy when he is still at a distance,
and he takes steps to catch the enemy by exploding a camouflet, whose
only effect is to retard his own work.


_Defensive system._--Two arrangements can be adopted: Fan-shaped
arrangement (Fig. A) or arrangement of independent parallel galleries
(Fig. B). The second arrangement is preferable.

_Interval between galleries._--Arrangement 2 being adopted, calculate
the interval between two neighboring galleries in such manner as to
prevent the enemy working underground. At the head of each gallery
two elbows of 6 meters, with boring chambers, are made. A 6-meter
boring is made from each chamber. At the bottom of the boring a
camouflet is placed, effective for radius of 6 meters (not more
heavily charged or the gallery will be demolished). The camouflet of
the neighboring gallery forms a tangent to the first. The interval
between the two galleries can not, therefore, be greater than 36
meters. In practice we would take 30 meters.

_Start, depth, and progress of work._--Start from first line. Start
at 4 meters, with a slope of 20 per cent to 30 per cent down to a
depth of 10 meters. Then horizontal. Length to gallery and return
without ventilation can cover 30 meters.

[Illustration: Fig. A. Fig. B.]

_Barrage trench for miners._--If the enemy passes in spite of
everything, the explosion should at least have been foreseen. The
enemy's attack must be limited or stopped, and this is always
possible after the explosion of the charge, which may explode well
in advance of our lines and act only as a strong means of launching
his attack. The barrage trench is established at from 40 to 50 meters
in rear of the salient T (Fig. B). In front of the parapet T, wire
entanglement R, and two machine-gun positions M^1 and M^2 are placed.
When the enemy's explosion is near, only a few men are left to occupy
the salient. The German explosion does not bury anyone, and when the
attack is launched it breaks down at the entanglement R.

_Camouflet._--The sector commander is warned when the defense is
about to explode a camouflet. About 10 meters on each side of the
gallery are evacuated as a precaution. The only danger is in having
several sandbags fall on the sides of the gallery entrance. Warn the
working party charged with the relief, in order that they may not
block the passage of men in the first line. Do not fire or make any
changes in that part of the trench, in order that the enemy may not
locate the position. Do not fire rockets before a given time. The
camouflet sometimes shakes the ground and dust is visible. Nine times
out of ten the camouflet is used at night.

When the enemy explodes a camouflet, fire a quantity of rockets to
locate the positions. Fire grenades and throw bombs at the presumable
position of the gallery. Send several men in front of the parapet to
listen to what is going on in the enemy trench.

_Offensive galleries._--These are intended to pass under the
adversary's defenses. Depth.--Start at first line when it is far
enough away from the enemy. Start at second line, or at special
communication trench about 20 meters in the rear of the first line,
when the enemy trench is too near. (See preceding.) A depth of 15
to 18 meters should be attained. The work is done as in ordinary

[Illustration: Fig. C.]

_Superimposed galleries._--This procedure gives splendid results
in deceiving the enemy, who thinks he is protecting himself. The
defensive gallery starts at the first line and the offensive gallery
starts in rear of it. Both galleries are on the same vertical plane,
the second being more advanced in the direction of the enemy than
the first. An enemy listener easily confuses one with the other, and
the offensive gallery passes under him. (See Fig. C.) Distances D
and D^1 are the same. The miner, M, confuses the two sounds, and the
offensive gallery passes under him.

_Mine chambers._--They are of special interest to the Engineer Corps
from a technical point of view. The best hours for exploding them are
4 a. m. and 7 p. m. When an attack is launched at a great distance,
or when there is to be no attack, the explosion is preceded by
several minutes of noise in the trenches. We commence firing and show
several bayonets over the parapet. The enemy believes an attack is
coming, comes out of his shelter, and mans his trenches. After the
explosion we fire on the mine crater for four hours with artillery,
grenades, and bombs. This fire should cover all the area exploded by
the mine chamber and should prevent any help to the wounded or buried.

_Launching an attack by means of mining._--The mine is an
irresistible means of launching an attack. In a mined sector the best
troops completely lose their bearings for several seconds after an
explosion. These several seconds prevent the machine gun from firing,
and the assailant gains a foothold in the first line and often in the

A mine attack should be prepared in the following manner:

Several days beforehand the attacking troops are sent to the rest
camp. The plan of the jumping-off trenches, the trenches to be
attacked, the ground trace of the crater, and the zone of the
searchlights are drawn on the ground with chalk. Each attacking
fraction is placed in position, with the matériel to be carried.
Each fraction's line of advance is marked out in chalk, as well as
the section of the enemy's trench to be occupied and the position of
the barrage. Every detail is studied thoroughly, and the exercise
repeated a dozen times. The attack is then carried out as planned.

_Craters._--The question of the occupation of craters must be decided
by an authority higher than the platoon commander. In certain cases
it is well to occupy them; in others, inadvisable. We will discuss
only the practical work to be done in each case.

_Craters to be occupied._--Crown the rim on the enemy side with
a continuous trench, joined to the lines by (at least) two
communicating trenches. Run out galleries in three directions, first
for protection and later for use in the attack. Construct bombproofs
on the half cone on the enemy side.

A crater is a position advantageous for the construction of auxiliary
defenses, for the removal of earth from the galleries, for massing
troops for an attack, and for flanking the lines.

_Craters that the enemy occupies._--They should be hampered with
bombs and grenades. We should head off the enemy by means of two
well-placed mine chambers, which are always possible to fire rapidly
when the scheme of defense is by independent galleries.

_Craters not occupied._--It is well to see what goes on at the
bottom. An outpost of several men or a sentinel may be posted for
this purpose in a communicating trench on the friendly rim. Two
communicating trenches may also be used to crown the friendly rim
with a trench with slight counterslope. The outposts place a dozen
loopholes permitting fire on the bottom. We may also fill up the
bottom with chevaux de frise and other auxiliary obstacles that can
be thrown in. If the craters are in the way, we can always turn them
by mining. (See figures for different examples:)

[Illustration: Fig. I.

--Example of Mine Craters--

  1 Mine Crater to be occupied
  t First line trench
  E Crater
  B B^1 B^2 Communicating trench
  T Trench crowning rim on enemy side
  M M^1 Machine gun on flanks
  E E^1 E^2 New galleries
  R Wire entanglement]

[Illustration: Fig. II.

--Mine Crater occupied by the enemy--

  E Mine Crater
  T 1^{st} line trench
  G^1 Gallery destroyed by explosion
  G G^2 Intact galleries allowing explosions to be placed
  F F^2 Which fill up enemy crater]

[Illustration: Fig. III.

--Mine crater not to be occupied--

  t Jumping off trench
  T Trench crowning friendly rim
  1 2 3 4 5 Loopholes overlooking the bottom and enemy rim
  M M^1 Flanking automatic rifle
  R Wire entanglement]

[Illustration: Fig. IV. Mine Crater between two lines


  Create an elevated earth position for
  placing machine guns or throwing bombs
  at M and M^1 which enfilade the portion t & t^1
  of enemy trench.]

[Illustration: Fig. V. Mine Crater for flanking purposes, see Fig. I
& III.

Fig. VI. Destroying a portion of enemy trench by means of two mine

  B B^1 Communicating German trenches cut off by explosion.
  S S^1 Salient under which E.E are exploded.

All flanking machine guns between S & S^1 cut off by rims of craters.]


  Obvious typographical errors and punctuation errors have been
  corrected after careful comparison with other occurrences within
  the text and consultation of external sources.

  Except for those changes noted below, all misspellings in the text,
  and inconsistent or archaic usage, have been retained.

  Pg 8: '(fig. a)' replaced by '(Fig. A)'.
  Pg 8: '(fig. b)' replaced by '(Fig. B)'.
  Pg 9: '(fig. 2)' replaced by '(Fig. B)'.
  Pg 9: 'positions M and' replaced by 'positions M^1 and'.
  Pg 10: '(See figure.)' replaced by '(See Fig. C.)'.

*** End of this LibraryBlog Digital Book "Use of Mines in Trench Warfare - From the French School of St. Cyr" ***

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