SOME PRINCIPLES OF MINING
Mining is an effective weapon, but it must be applied to suitable
objectives, and its use restricted by certain rules which have been
deduced from experience.
As regards the actual processes, the only important changes to be
anticipated are the development of the use of rapid tools and of high
explosives.
The most vulnerable points in trench-mine warfare are the following:
Listening and observation posts in advance of the line; machine-gun
and trench-mortar positions; junction-points of communicating-trenches
with front line.
Mines were employed to attack, and countermines to defend, many
besieged cities in the past, but the application of mining methods in
trench warfare has at no time or place reached the scientific
development which obtains in the present war, though our own Civil War
furnishes several examples of its use in connection with the trench
fighting of those days, viz.: Petersburg, Va., and other localities.
The situation of the western front is briefly as follows: Some
thousands of mines have been blown by the Germans, British, and
French, many of them with very large charges. The British and French
were mostly engaged in defensive operations during 1915 and a portion
of 1916, but since that date the application of mining methods by the
Allies has been mostly on the offensive. Wherever opposing trenches
are close together, mining warfare has almost invariably ensued.
Mining fluctuates from time to time, and in 1915 and 1916 was most
active on this front. It is always a possibility to be reckoned with,
although the element of surprise, the most important factor in
offensive mining operations, has now been largely discounted. On the
other hand, the field of mining activity has been enlarged and is
constantly changing. The destruction of enemy strong points is now an
important problem for mining engineers. The use of mines in destroying
roads and shelters also, in what might be described as the half-open
warfare which has been so common this year, and in strategical
retreats, is of increasing importance. The necessity of training
engineer-pioneer units is important, as in the absence of special
mining troops, this work may fall to their lot, particularly in the
case of defensive operations in order to protect the infantry.
On account of the large number of men, quantity of material, expense,
etc., the use of mining operations is very carefully considered
beforehand, and careful plans devised before starting on any
underground operations. Attacks are sometimes undertaken only to
demolish a portion of the hostile trenches, in view of a local
operation. At other times they form a part of a large offensive
movement. Generally speaking, speed and silence are the first
requisites. If these can be obtained with any degree of certainty,
mining operations are nearly always successful. In the underground
struggle in this war, the forces with superior personnel, material,
and explosives at their disposal are bound to win, this is a fact
proven by actual experience. The objectives will be usually such
points as cannot be destroyed by artillery-fire, areas organized with
deep dugouts and strong points which form valuable objectives, etc.
Almost everywhere on the western front the enemy are intrenched in
deep, well-constructed trenches, and in nearly every area these
trenches are further fortified by numerous deep dugouts and
underground galleries, in most cases close-timbered with four-inch oak
and other hard woods. The German mine systems are also almost
invariably close-timbered.
In the same way as the general principles of tactics in open warfare
agree with those of trench warfare, they are guided by the same
logical reasoning. Many considerations must be studied before adopting
any plan of offense.
With regard to depth below the surface, the miner must be guided by
the elevation of his objective and by the nature of the strata through
which he will have to work. In most operations the water-level is an
important factor in considering depth.
It must be always borne in mind that mining is not an independent
service, but is employed in connection with the other arms of the
service.
Underground activity, either offensive or defensive, is first observed
from those points in our lines nearest the enemy. All enemy trenches
facing salients of our lines will be the object of particular
attention and closest daily observation. This observation of the
first-line and support-line trenches should disclose the presence of
enemy underground works and their approximate location. For their
definite location, the most careful listening underground must be
done.
Aeroplane pictures are a source of much valuable information if
studied very carefully. Aeroplane photographs covering several weeks,
and if possible several months, are procured from the nearest squadron
of the air service. The use of a strong magnifying glass will probably
discover chalk mounds where fresh heaps are, by comparison with
previous aeroplane photographs, shown to be growing in size; and other
features or changes which will afford useful information on careful
study. Particular attention is paid to new trenches in the enemy's
lines. In fact, any change from week to week in these aeroplane
photographs is carefully accounted for. If further pictures are
desired, particularly just after craters have been blown by the enemy
or ourselves, they are furnished by the air service. The enemy's lines
are studied from day to day with field-glasses. Perhaps the
accumulation of sand-bags different in color to the others will be
noticed, or freshly placed earth, white and less dull in color than
that of the parapets, which have been washed by the rain and blackened
by explosives. As a matter of fact, in mining operations in Flanders,
where blue clay was encountered, the bags containing the clay
(different in color to surface clay) were so distributed along the
front-line trenches or breastworks on both the enemy and British
trenches that it was a matter of considerable difficulty to obtain
much information from this source. It was, of course, common knowledge
that both sides were engaged in mining and fairly accurate information
as to position of enemy galleries was deduced, but the actual location
of enemy mine-shafts was very difficult to determine, as quite a
number of mine-shafts emanate from dugouts and are connected up with
others.
Listening reports give a fair idea of where the enemy's galleries are,
and plans are made up showing the suspected location of enemy
galleries or mine system. These plans are developed in accordance with
the evidence furnished. Careful observation may show that a number of
men come up the communication-trenches regularly to certain spots and
there disappear from view. One may notice carrying parties coming up
with timber, by catching sight of the timber above the trench.
Infantry listening patrols, who have been listening in "No Man's Land"
at night may have heard the sound of machinery or ventilators at work,
or some other sounds which go to prove the existence of enemy mining,
or the location of mine-shafts, etc. It is important to listen in "No
Man's Land" at night, in order to obtain definite information or
confirm the reports from infantry.
Sufficient evidence being obtained as to probable location of enemy
mine-shafts, or dugout entrances, etc., there is difficulty in having
these places "strafed" by our own trench-mortars and artillery.
In the desire to obtain evidence of the enemy's activity underground,
the proper camouflage of one's own spoil-heaps and entrances cannot be
neglected.
It is essential to have a scheme of attack. Numerous attacks have
failed on account of there being no clearly thought-out plan. A common
mistake has been failure to anticipate possible counter-mining by the
enemy, and to commence the attack without guarding against it.
Study of the objective and the ground will therefore furnish the
information necessary to settle the essential elements of the scheme.
The attacks must be arranged so as to reach the objective in spite of
anything the enemy may do. The vulnerable parts are the flanks; that
is, both the flanks of galleries or branch galleries which are first
constructed, and also the flanks of the combined scheme.
Usually it is of no advantage to begin an offensive by mining if the
enemy has covered his position with countermines; if the distance to
be covered is more than 150 yards; or if the water-level is very
shallow.
There should be more galleries than the actual number needed to reach
the objective.
They should be placed close enough to each other to insure enemy
operations being detected from either parallel gallery.
If the enemy tries to bar the way by counter-mining, a breach must be
made in his system, so that, in spite of him, the galleries may be
driven to their objectives and charges placed as previously arranged.
The underground struggle which ensues must aim at clearing the ground
by destroying the enemy's galleries, and at holding him to one part of
the front whilst the attack passes elsewhere (to one side, above or
below) by working quicker.
In order to do this successfully, it is necessary to get ahead of the
enemy and strike before he can do so, to go for the flanks of the
enemy's galleries, to strike as hard as possible, and to strike only
when within good range.
To insure this it is required to have an accurate plan of the mines, a
well-organized system of information, and decision and rapidity in
execution. The value of a blow on the enemy's flank by placing the
charges at the sides of branches or galleries will be enhanced.
In meeting the enemy underground, maximum-charge camouflets are
largely employed. These will naturally vary with the depths at which
they are placed.
To strike within good range requires great coolness. Every explosion
causes a temporary delay in the attack, because it will damage part of
the gallery leading to the charge. A mine should be fired only when it
is considered that it is likely to do more damage to the enemy than to
ourselves.
[Illustration]
The preceding sketch illustrates a plan adopted by the French which
may be used in suitable soil for the offensive. This procedure often
gives good results in deceiving the enemy. He thinks he is protecting
himself. The defensive gallery starts from the front line and the
offensive from the support. Both galleries are in the same vertical
plane, the second being more advanced in the direction of the enemy.
In the top galleries very little attempt is made to deaden the noise,
while work below is carried on silently. An enemy listener easily
confuses one with the other, and the offensive gallery passes under
him. Distances D and D1 are the same. The miner M confuses the two
sounds, and the offensive gallery passes under him.
(NOTE: In many of the districts in France, where a sandy clay forms
the top-soil and a hard chalk the subsoil, this method could only be
adopted with difficulty, as the conditions are reversed. The top
gallery being in clay, it would be comparatively easy to do noiseless
work there, but extremely difficult to carry on the lower chalk
gallery without noise.)
Referring to sketch C, direct attack may be made in this manner, or
this method might be used as a feint, while the enemy is driven around
behind the gallery at another point.
The usual measures of precaution employed in ordinary warfare above
ground must be taken below ground whenever the distance of the enemy
and the nature of the soil do not exclude all possibility of a mining
attack.
It is essential to have: An efficient lookout and listening service
(observation of enemy's work above ground, and listening-posts above
and below); Means of defense underground--countermines.
The most reliable information will be obtained by underground
listening with portable listening-instruments, such as the geophone,
etc. Much confirmatory evidence is obtained by listening patrols at
night in "No Man's Land" and by a careful survey of enemy trenches.
Several different arrangements can be adopted. The fan-shaped
arrangement as shown in Fig. B, or the arrangement of independent
parallel galleries (Fig. C). The second arrangement is preferable. The
interval between galleries varies with range of listening in different
soils. In clay, the distances between galleries should not be greater
than 60 feet. In chalk this may be safely doubled. Listening-galleries
are usually put out in Y-form, and these galleries are of smaller
size, often 3 feet by 2 feet in cross-section. If desired, holes may
be bored from the ends of these listening-galleries and geophones
placed in them. Where time, material, and personnel permit, the
mine-shaft is put in at the support-line instead of from the front
line. This can only be done, however, when the situation allows of it.
The galleries in Flanders seldom reach a greater depth than 25 feet to
30 feet, but in the districts farther south, in the chalk country,
mining operations are conducted at any depth from 80 to 150 feet. A
comprehensive German mine system was found in the Somme district at
200 feet. Naturally, it is a distinct advantage to get one's own
defensive system in first and then sit tight and listen for enemy
work.
The best defensive is often a strong offensive. A concrete instance of
this is furnished by the experience of a British mining company who
were ordered from Flanders to trenches in the chalk district at the
Vimy Ridge to meet what was termed "an urgent situation" underground.
The Germans were mining from chalk galleries at depths varying from 60
to 100 feet, and inflicting heavy casualties on the infantry occupying
the British trenches by blowing large mines under their advanced
positions. As a result the infantry were obliged to abandon many of
these forward positions. The hard chalk subsoil of this district was
covered with a sandy clay top-soil varying in thickness on this sector
from 1 to 30 feet in depth. Some defensive galleries in the chalk had
been started by the French miners when occupying these trenches. The
British at once undertook the construction of numerous galleries in
the clay top-soil. Their rate of progress was much faster in clay than
that of their opponents in chalk, in addition to which they could
proceed without noise. The programme was daring but entirely
successful. The enemy continued to handicap their efforts at the
outset by blowing often, but within some six weeks the British had
succeeded in completely establishing their mastery underground. A few
camouflets were blown by them in crossing "No Man's Land," but the
majority of their mines were fired directly below the enemy's first
line, and in some cases beyond. So intense was the fighting that on
some occasions the British blew as many as four mines a night on a
500-yard front.
The question of the blowing and occupation of craters is usually
determined in consultation with the infantry staff. Some occasions
occur, as, for instance, when the enemy is met below ground, when it
is necessary to fire charges which will form craters; but, as a rule,
no craters are blown in "No Man's Land" until the infantry have been
warned and plans made for their occupation or otherwise.
Camouflets are employed to a large extent to destroy enemy galleries
when they are met below ground. The infantry officers occupying the
trenches are always informed of an impending "blow" from the enemy,
and dispositions are made to withdraw any troops occupying dangerous
positions, such as outlying bombers' posts or automatic-rifle
detachments, etc.
[Illustration: FIG. B]
[Illustration: FIG. C]
All ranks in the mining companies are warned not to create an alarm
among the infantry occupying the trenches when enemy "blows" are
anticipated. Mining officers, at their discretion, advise the infantry
of the state of affairs when there is very active fighting underground
and there is danger of casualties among the infantry from enemy
"blows." Only in the latter event is it wise to inform them. Under
ordinary circumstances, no information should be given. Considerable
success in warning infantry of impending mines by the enemy has been
reached by the British and French miners. They often estimate the time
of enemy mines being blown to within a few hours. On the other hand,
the enemy often prepare charges and hold them for long periods before
firing.
It is most important to ascertain, by underground listening, the
nature of the work done. Determination of the nature of the sounds in
listening is of equal importance to their location.
The practice of blowing craters on every occasion in "No Man's Land"
is discouraged, generally on account of the fact that it will prove an
obstacle in the assault when the next infantry attack takes place.
Many craters are blown for tactical reasons, such as the obtaining of
good observation-posts and, in other cases, to obtain enfilade fire
from the rim of the craters blown. Previous to blowing these craters,
plans will have been made with the infantry to consolidate them as
soon as blown. The exact diameter of the crater will have been
calculated and the position located in "No Man's Land," and a trench
constructed, probably the previous night, which will intersect the rim
of the proposed crater. As soon as the mine is blown, the infantry
will consolidate their positions on the rims of the craters. Many
craters are used to good advantage in the disposal of spoil from
near-by mine-shafts. Considerable difficulty is found in obtaining new
places in which to dump the spoil, especially on active mining
sectors.
Many devices are employed to deceive the enemy when firing. Dummy
picks are often suspended in the face of the gallery and operated
regularly to imitate picking, etc. Other sounds indicating progress
of ordinary work may be simulated in the gallery being charged, or
perhaps rather noisy work going on in an adjacent tunnel. A little
ingenuity here is advisable. Quite a large number of mines are fired
at "stand-to" at dawn or dusk, average time, 4 A.M. or 7 P.M.,
depending on the time of year. Naturally, it is not wise to make
these times regular. The "stand-to" times are common because of the
fact that the enemy infantry also occupies his fire steps at these
times. Care must be taken to withdraw troops occupying dangerous
positions.
In the event of blowing a series of mines under the enemy trenches,
plans are devised with the infantry in an endeavor to induce the enemy
to occupy his threatened trenches in force. This may be effected by a
"false" infantry attack, and other means.
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-guns from firing, and the assailant gains a foothold in the
first line, and often in the second. The extent of the underground
operations in launching an attack naturally depends upon the size of
the offensive, whether it be a battalion, brigade, division, or army
offensive. The date has been set for the general attack. Mining units,
in consultation with the staff of the forces employed, will elaborate
their plans for the mining operations. (The battle of Messines
furnished an excellent illustration of the value and use of extensive
mining in launching an attack. In these operations, the British miners
fired a large number of mines from galleries under the enemy front
line, and in some cases below their supports. The charges in these
mines varied from 15 to 50 tons each, and were all fired at "zero"
hour, the minute at which the infantry goes over the top. Nine hundred
and fifty thousand pounds of ammonal were used. Some mines had been
charged for fourteen months and others for a year. One charge of
95,000 pounds formed a crater 125 feet deep with 186 feet diameter.
The largest crater formed was from a charge of 70,000 pounds, depth of
crater 86 feet, diameter 260 feet. These mines were in chalk and clay.
The result was a complete demoralization of the enemy, and the first
objectives were obtained with very few casualties.) The Germans
deserted their lines for half a mile to the rear. These mines were
fired on a front of several kilometres. The scheme of the offensive
having been planned, galleries are driven under the enemy trenches and
all charges laid ready for firing.
Throughout the brigade or unit attacking, all watches carried by
officers are synchronized so that at "zero" time all mines are fired
simultaneously. Frequently mining units are detailed to go over with
the infantry in raids, or follow them over in attacks, for special
demolition work, in which event they will usually carry portable
charges of high explosives, and destroy enemy mine-shafts, dugouts,
etc.
The use of mining to destroy the numerous enemy reinforced concrete
shelters is now coming to the fore. Artillery-fire, even of the
heaviest character, often fails to destroy these shelters, and
engineers are called on to destroy them by tunnelling and firing with
high explosives. In most cases, it is usually essential for the
success of the work that a sufficient depth of clay is found, in order
to proceed without noise. On some occasions they have been destroyed
from tunnels in chalk, but this is increasingly difficult with the
enemy's improved methods of listening. Smaller galleries must usually
be driven. It often happens that very little cover to these galleries
can be obtained and the work is more hazardous, but the success of
these operations is undoubted if careful measures are adopted.
In June, 1917, the writer's company destroyed a German reinforced
concrete machine-gun post by tunnelling from the Hindenburg line for a
distance of 200 feet, through an average of 7 feet of clay above the
chalk. For most of the distance, only 2 feet of cover was possible,
but the operation was completed in a few days, and with a charge of
500 pounds of ammonal, placed right up against the concrete, succeeded
in entirely destroying this German defense, and largely assisted the
infantry in capturing another 500 yards of the enemy Hindenburg
trench.
In the instance referred to, the enemy had a listening instrument set
up in the chalk, but had evidently failed to hear the work in the clay
above.
Nearly all the German trenches are undermined by a series of
subterranean galleries, thirty feet or more in depth. As they retreat,
in addition to building blocks or breastworks in the trench on top,
they will also blow the tunnels underground. It sometimes happens,
however, that these underground galleries are not destroyed behind
them, and the enemy have taken advantage of this situation by waiting
until the trenches are occupied in force by the pursuing troops, and
then blowing big mines under them. Careful investigation of the enemy
trenches occupied after an advance is essential, though this obvious
precaution is sometimes overlooked. In all mining work of this
character, speed and silence are of first importance.
_No. 55._
LINE CORPS SUMMARY OF INFORMATION
Received up to 6 p.m., 17th August, 191--
_CONFIDENTIAL._ This document is not to go beyond Battalion
or Battery Commanders who are responsible that no copies risk
falling into the enemy's hands.
1. _BRITISH OPERATIONS._
1. (_a_) During last night and to-day on the _11th Divisional
front_ the 6th Lincolns Regiment and the 6th Border Regiment,
by a series of enterprising patrols and bombing attacks,
succeeded in occupying the whole of CONSTANCE TRENCH up to R.
33. a. 5. 4., near which touch was established with the 34th
Brigade on their right, the whole of DANUBE TRENCH was also
occupied and bombing posts pushed out to near JOSEPH'S TRENCH
in R. 32. b.
The enemy who had been holding these trenches fled in
considerable confusion, leaving their rifles behind them.
Point R. 32. c. 3. 9. was also occupied and direct
communication opened with the 49th Division holding the
LEIPZIG SPUR.
(_b_) On the 49th _Divisional front 2_ (diagonal) Lieut.
Storm of the 5th York and Lancaster Regiment, who had been
ordered to obtain an important identification, personally
reconnoitred the enemy's trenches about R. 19. c. 8. 4.
Returning he then led two platoons against the selected point
and succeeded in forcing an entry. Considerable losses were
inflicted on the enemy both by our surprise artillery barrage
and during the bayonet and bomb fight which followed.
The one prisoner necessary for identification purposes was
duly brought away and the raiders returned with a loss of one
man killed and a few wounded.
(_c_) A German 5.9 Howitzer originally captured by the 48th
Division near R. 32. c. 9. 1. and since covered by shell earth
has been found again to-day.
2. A hostile balloon (location unreported) was seen to fall in
flames about 3 p.m.
3. _Artillery._
25 direct hits on emplacements have been reported during the last
24 hours.
At one position the pit was entirely blown away, 2 explosions
occurred, and the dugout into which 2 Officers had been seen to
run received 2 direct hits; several corpses were seen lying about.
About 12 noon to-day one of our batteries caused a large explosion
at R. 26. c. 3. 4. This was probably an ammunition store which has
been reported by several prisoners to be located at this point.
4. _Prisoners._
During the last 24 hours 9 prisoners have been captured by the II
Corps, of which 7 were wounded.
Total captured by II Corps up to 6 p.m. on 17th 26 Officers and
1,523 other ranks.
Total captured by Reserve Army up to 6 p.m. yesterday 77
Officers, 4,478 other ranks (including 970 wounded).
2. _ENEMY'S OPERATIONS AND MOVEMENTS._
1. Air reconnaissances carried out this morning report
that a considerable train movement on the line from
CAMBRAI to BAPAUME.
No large movements of troops or transport were seen on the
roads in the area opposite the Corps front.
2. Much traffic on the IRLES-GREVILLERS Road, both ways,
is again reported.
3. SCHWABEN TRENCH is evidently occupied round about R.
33. a. 2. 7., men having been seen moving around there
during the day.
4. Yesterday the enemy blew up ammunition in evacuated gun
pits to the Northeast of COURCELETTE, but it cannot be
said there are definite signs at present of withdrawal
from the line South of the ANCRE.
5. _Hostile Artillery Activity._
Normal during the last 24 hours. LEIPZIG Salient, AVELUY,
PIONEER ROAD in W. 16. b., the MESNIL area, WONDER WORK
and THIEPVAL WOOD have been shelled during the day.
Enemy's trench mortars have been quiet.
3._ ENEMY'S DISTRIBUTION, DISPOSITIONS and ORDER OF BATTLE._
See Annexe.
4. _ENEMY'S DEFENCES._
(_a_) Machine Guns.
An emplacement, believed to be new, has appeared in BULGAR
Trench about R. 26. a. 2. 4.
Machine Guns have been located at:--
R. 25. b. 7. 7. }
R. 19. c. 1. 5. } Prisoners statement
Q. 24. b. 1. 1. }
R. 27. c. 3. 8. }
(_b_) _Dugouts Reported Occupied._
R. 31. a. 53. 37.
R. 32. a. 0. 9. to 2. 8.--holding 1 Company of the 77th R.I.R.
(Prisoners statement).
R. 27. d. 1/2. 3.
(_c_) _Headquarters Located._
H.Q. of the 45th Res. Divn. is reported to be in HAPLINCOURT.
H.Q. of the 212th Res. Regt. HAPLINCOURT.
H.Q. of the 211th Res. Regt. LE BARQUE. Battle H.Q. of this
Regt. is in dugouts about 200 yards behind WARLENCOURT.
[Illustration: ROUGH SKETCH ILLUSTRATING BREASTWORKS AND SYSTEMS OF
UNDERGROUND GALLERIES.
Dotted lines represent galleries and tunnels from twenty to
twenty-five feet underground.]
* * * * * *
Transcriber's note:
Minor typographical errors have been corrected without note.
Irregularities and inconsistencies in the text have been retained as
printed.