WAR

DEPARTMENT

CO P SOFFIELD

MANUALENGINEERS

FIELD
FORTIFICATIONSWAR DEPARTMENT : 14 FEBRUARY,

1944

WAR

DEPAR TMENT FIELD MANUALFMA 5-15

Tii, manual supnrde FM 5-15, October 940, including C 1, 2April 1941, andC 2, 10 December 1941; and .o murA of Training Cireular ,o.52,. ar Departmenl.
1943.
1942, as prtains lo FM 5-15; Trainnt Circa.a No. 96, War Departmntr,

CORPS

OF

ENGINEERS

FIELD
FORTIFICATIONSWAR DEPA4RTMENT

I4 FEBRUARY 1944

Unted Sa4,r Covrnmet Prinnt Offic
r'asltingto
J944

WAR DEPARTMENT,
WAsIfaNGTON 25, D. C., 14 February 1944.
FM 5-15, Corps of Engineers Field Manual, Field
Fortifications, is published for the information andguidance of all concerned.
[A. G. 300.7 (16 Jun 48).]
BY ORDER OF TIJE SECRETARY OF WAR:

G. C. MARSHALL,

Chief o Staff.
O1FICIAL:

J. A. ULIO,
Major General,
T'he Adjutant General.
DISTRIBUTION:

B and H 1, 2, 4, 6, 7,17, 44 (4); R 1-4, 6, 7,17, 18,
44 (5); Bn and H 5,19 (5); C 5 (10).
(For explanation of symbols see FM 21-6.)

CONTENTS

Parraiphs

Page

1
1-2
.-_-_.----.
CHAPTER 1. GENERALCHAPTER 2. TERRAIN EVALUAT.ION.
3
3-9
Section 1. General -.------------------7
II. Aids to the study of terrain --_ 10-11
12-17
23
III. Tactical study of terrain .---CHAPTER 3. GENERAL FORTIFICATION TECHNIQUE.
26
Section I. Tools and materials -.-------- 18-19
28
20-27
....
II. General technique ..-. .
CHAPTER 4. ENTRENCHMENTS
AND EMPLACEMENTS.
.... 28-29
47
Section I. General -.-.-.-..
forentrenchments
II. Infantry
48..... 30-36.
hasty fortifications -.
III. Infantry weapon emplace58
37-46
ments -.------------------81
IV. Special and standard trench ... 47-48
V. Field artillery emplacements --- 49-57
86
VI. Antiaircraft artillery emplace102
ments --------------------. 58-65
CHAPTER 5. SHELTERS.
66-72
126
.-------------------Section 1. General156
II. Surface shelters -.------------ 73 74.-------75-76
165
111. Cut-and-cover shelters..... ___.. - 77-92
181
IV. Cave shelters 221
APPENDIX 1. Glossary of terms.-------- _------II. Effects of bombs and projec....
224
tiles
…....
1-3
III. Concrete machine-gun em.
1-4..........
229
placement.1-3
236
IV. 40-mm Antiaircrafttower --269
INDEX.-........--

This manual supersedes FM 5-15,
October 1940, includitg 0 1,
This ranual supersedes FM 5.15, 1 October 1940, including C 1,
(iroular No. 52, War Department, 1904, as pertains to F 15-15.

CHAPTER 1
GENERAL

1. PURPOSE AND SCOPE. Troops in occupied positions increase their combat effectiveness by works ofan engineering nature called field fortifications. Thismanual describes field fortification methods and gives
details of construction of entrenehments, emplacements.
and shelters. It also outlines the principles of terrain
appreciation which apply to field fortifications, and explains how to combine individual field fortifications
into a unified system by means of organization of theground. It does not cover the subject of obstacles, which
is treated in FM 5-30.
2. CLASSIFICATION AND USE OF FIELD FORTIFICATIONS. a. Classification. There are two generalclasses of field fortifications.
(1) Hasty fortifications. Those initially constructed when in contact with the enemy or when contact is imminent. They consist generally of light clearing of fields of fire, foxholes for personnel, open weapon
emplacements, hasty antitank and antipersonnel minefields, barbed-wire entanglements, strengthening of
naturalobstacles, observation posts, and camouflage.
(2) Deliberate fortifications. Those constructed
out of contact with the enemy, or developed graduallyIfrom hasty fortifications. They include deliberate entrenchments, antitank and antipersonnel mine fields,
antitank obstacles, covered weapon emplacements,
barbed-wire entanglements, troop shelters which are
proof against artillery fire and weather, extensive signal
communication systems, gasproof inclosures of command posts and aid stations, and elaborate camouflage.
b. Use. Field fortifications increase the combat efficiency of troops. 'They must be used skillfully tofurther the mission of a unit, and must not be allowed
to lead to a passive or static defense. The decisions as
to whether or not to occupy a position and the degree of
fortification to undertake are primarily tactical andbeyond the scope of this manual2

CHAPTER 2TERRAIN E VAL UA TIONSECTION I
GENERAL
3. PURPOSE. The purpose of this chapter is to describe the means of evaluating terrain. For a detailed
discussion of the effect of terrain on tactical dispositions and for information on organization of the ground,
see FM 100-5, 7-10, 7-15, 7-20, and 740.
4. DEFINITIONS. a. Terrain, from a military viewpoint, is an area of ground considered in relation toits use for military purposes.
b. Terrain evaluation is the analysis of the area ofprobable military operations, to determine the effectof the terrain on the lines of action open to opposing
forces in the area.
5. INFLUENCE OF TERRAIN. a. The character of
the area or region of military operations often has adecisive influence upon the course of operations. The
more important factors to be considered in evaluating
terrain include not only natural features, such as ridges,3

streams, bodies of water, woods, and open spaces, butalso such features as roads, railways, and towns.
b. Ground forms, such as a succession of ridges andvalleys, influence military operations by aiding or
hampering the movement of military forces. An advance parallel to the ridges and valleys is mechanicallyeasier than movement across successive ridges.
e. The salient feature of a commander's plan ofaction are usually determined so as to take full advantage of favorable terrain features.
6. TERRAIN FACTORS. Regardless of the type ofterrain and the tactical situation, terrain always can beevaluated in terms of the following five factors: observation, fields of fire, concealment and cover, obstacles,
and communications.
a. Observation. Observation of the ground on
which a fight is taking place is essential in order tobring effective fire to bear upon the enemy. Observation also aids in increasing the effectiveness of fire
directed on an enemy stopped by obstacles. The valueof cover and concealment is based on denial of observation to the enemy. Observation also affords information as to what both enemy and friendly troops are
doing, making it possible for the commander to control
more effectively the operations of his troops.
b. Fields of fire. Fields of fire are essential to thedefense. An ideal field of fire for infantry is an open
stretch of ground in which the enemy can be seen andin which he has no protection from fire as far as thelimits of effective range of the infantry weapons.
Fields of fire can be improved by cutting or burning
weeds, grass, and crops; clearing brush and trees; demolishing buildings; and cutting lanes through woods.
4However, concealment must be carefully considered inall such work. The time and labor available for thistype of improvement should be considered in evaluating the terrain.
c. Concealment and cover. Concealment fromview, both from the air and ground, will usually protect military personnel and installations only as longas the enemy is unaware of their location. Unconcealed
installations and troops invite destruction. Cover includes protection from fire, either that provided by
the terrain, or that provided by other natural or artificial means.
d. Obstacles. Obstacles are obstructions to the
movement of military forces. Some of the common
natural obstacles of military value are mountains,rivers, streams, bodies of water, marshes, gullies, steep
inclines, and heavily wooded terrain. Proper evaluation of natural obstacles permits the most effective useof artificial obstacles.
(1) Mountains parallel to the direction of advanceof a force limit or prohibit lateral movement and protect the flanks; perpendicular to the advance, they are
an obstacle to the attacker and an aid to the defender.
(2) Rivers are similar to mountains in their effecton forces moving parallel and perpendicular to them.
Rivers flowing parallel to the advance may be usedas routes of supply.
(3) Marshes frequently provide more delay to anadvance than bodies of water, because generally it ismore difficult to build causeways than bridges. Mechanized vehicles can be restricted in movement by dense
woods, marshes, steep inclines, gullies, stumps, large
rocks, and bodies of water.
e. Communications. Communications consist ofSroads, railroads, waterways, airways, and their facilities. They are important to both offense and defense
for moving troops and supplies. In most situations,especially in the operations of large bodies of troops,
the means of communication are of vital importance.
The existing ones generally must be studied thoroughly and utilized to the maximum before new ones areconstructed.
7. OBJECTIVES. Terrain objectives, normally. areclearly defined features, the capture of which will insure the defeat of a hostile force, or from which theoperation can be continued or the success exploited.
Terrain objectives, in the attack by ground forces, usually are located in, or in rear of, the hostile artillery
area. One may be a terrain feature affording command
observation, another a critical point in the hostile command system or on essential supply routes, and anotheran obstacle to armored forces. In some situations theobjective is clearly indicated by the mission; in others
it.is deduced from the situation.
8. MAPS AND RECONNAISSANCE. Maps are thebasis for terrain studies but should be checked by air
reconnaissance, air photographs, and ground reconnaissance. Works of man, especially routes of comnmunication, are changing constantly; and even natural
ground forms may, change.
9. CORRIDORS. Features such as ridges, streams,
woods, roads, and towns divide all terrain into moreor less separate areas. Such an area frequently consistsof a valley lying between two ridges or an open space
between two wooded areas. The limiting features pre6

vent direct fire or ground observation into the area;
they may be high or low, continuous or discontinuous.
When the longer axis of such an area extends in the
direction of movement of a force, or leads toward or into
a position, the area is called a corridor.

SECTION IIAIDS TO THE STUDY OFTERRAIN
10. GENERAL. Maps and aerial photographs, supplemented by ground and air reconnaissance, form thebasis for studying terrain. In many cases maps marked
in special ways simplify its study. Often a series of
special maps, on each of which is emphasized a separate
item of military importance such as roads, streams, or
ridges, is necessary. The purpose of this section is toindicate methods used in preparing such maps.
11. FEATURES OF MILITARY IMPORTANCE. a.
Ground forms. Drainage lines and ridge lines are thenatural basis for studying terrain with respect to theshape of the ground. Drainage lines always form aconnected system or systems of branching lines. Ridge
lines form similar systems of branching lines. Together, ridge and drainage lines form two interlocking
branching systems which, singly or together, clearly indicate the general shape of the ground.
(1) Figures 1 0 shows a section of a contoured map.
Figure 1 ( is the same map with the drainage lines emphasized. This is generally done in blue. Figure 1 (
7

V

w,

(D Section of contoured map before emphasis.
Figulre 1.
8

V

t

® Drainage lines emphasized
Figure 1-Continued.

9

-

I

'4·

() Rfidge lines emphasized.
Figure 1-Continued.
10

S) Drainage and ridge lines emphasized.
Figure 1--Continued.

ft~~~

4rC

·

K

/
toS;~

Fiur

-Cnirued~~~,%
0-ad70fot
o
ef.

12

12~~'I

ur

cntu

ie

I

mhszd

K-Catnu

''

3,BOE

700 FT

W 640 TO 700 FT
13 Different elevations emphasized by shading.
Figure l-Continued
s566397° 4--213emphasizes the ridge lines. Usually this is done inbrown or red. Figure 1 ) shows the drainage andridge lines emphasized on the same map. The more pronounced ridge and drainage lines are given special emphasis by marking them more heavily.
(2) In figure 1 () the 600- and 700-foot contours areemphasized with a heavy line. In figure 1 ( theground having an elevation over 640 feet has been indicated by light shading; ground with elevation over 700
feet, by darker shading; and ground with elevation
under 640 feet is unshaded. Elevations on a contoured
map frequently are emphasized by using a separate tint
or color for each range of elevation, to make groundforms and commanding elevations more apparent.
(3) Figure 2 () shows a section of a photomap, andfigure 2 () shows the same map after the drainage lines
have been emphasized. Usually, unless they are emphasized, it is quite difficult to follow the minor drainage lines on an aerial photograph or photomap. However, by stereoscopic examination of suitably overlapping aerial photographs, the minor drainage or ridge
lines easily may be distinguished.
(4) Figure 3 ( shows a section of an uncontoured
map. Although no contours are shown, a fairly accurate visual picture of the actual shape of the terrain
may be had by interpolating ridge lines halfway between drainage lines, as shown in figure 3 (). In general,main ridges divide principal drainage systems. Therefore, the approximate location of important ridge lines
usually can be determined, even though actual elevations
are not known.
b. Roads. Figure 3 () emphasizes roads. Roads ofdifferent classification or type can be indicated by different colors. For a division, a map of this nature is

14

(D Section of photomap.
Figure 2.
15

6 Section of photomnap with drainage lines emphasized.
Figure 2-Continued.
16

(D Section of uncontoured nmap.
Figure 3.
17

GEN( Ridge lines interpolated between stream lines.
Figure 3-Continued.

18

CENTERQ) Important roads emphasized.
Figure 3-Continued.
19(Railroads emphasized. Figures indicate siding capacities.
Circles indicate railroad yards.
Figure 3-Continued.

20

KEY
T-20 CAPAPCITY
2 ON

T~~~~~~~~L( DBridges and rivers emphasized.
©
emphasizeG.
Figure 3--Continued.
3-Continued.
21
21

often used to emphasize all roads which are able to carry
the division loads.
.. Railroads. Figure 3( emphasizes railroads.
Numbers indicate siding capacities and circles indicate
yards.
d. Bridges. Figure 30 emphasizes rivers andbridges with their capacities.
e. Other features of military importance. Other
features of military importance, such as natural resources and water resources, may be emphasized on special maps in a manner similar to that used for roads,
railroads, and bridges.

SECTION III
TACTICAL STUDY OF TERRAIN
12. PURPOSE. Evaluation of the terrain is an important element in every tactical operation. Its tactical study may be mental, oral, or written, depending
upon circumstances. It may be made by the commander himself, or by any subordinate designated byhim.
13. LIMITING CONSIDERATIONS. The t e r r a i n
studied should include all of the area involved in thecontemplated operation. The details of the study areaffected by other considerations. A commander making a tactical study of the terrain is limited by his
mission and by his own and the enemy's capabilities.
G-3, in preparing details of a tactical study of theterrain, is limited by the capabilities of his own force
22and by the commander's decision or directive for theoperation; G-2 usually is limited by the enemy's
capabilities. The specialist, such as the tank commander, the artillery commander, the chemical officer,or the engineer, will find his study limited by the powers
and limitations of his arm or service.
An y deductions
14. GENERAL TOPOGRAPHY.
made as to the tactical effects of the terrain must be
based on a knowledge of the topographical features of
the area under consideration. The following usuallyshould be considered:a. Drainage system. Streams and valleys are ofparticular importance because, together with the intervening ridges, they make up the general frameworkof the terrain.
b. Ridge system. This is the complement of thedrainage system and should be approached in the same
mannmer.
c. Routes of communication. The road net available for tactical maneuver or supply, the presence orabsence of rail facilities, navigable waters, and airplanelanding facilities, all come under this subhead.
d. General nature of the terrain. All the foregoing information is summarized briefly in a final
paragraph.
15. MILITARY ASPECTS OF TERRAIN. The facts
upon which further conclusions are based having beenstated, the study now proceeds to the evaluation andinterpretation of these from the military point of view.
At this point the study resembles an intelligence study,
an operations study, or both. As a means of systematization, the area is divided for purposes of discussion
23

into natural subareas; or, if there are no distinctive
natural boundaries, into subareas delimited with regard
to the tactical situation. Within each subarea, terrain
elements affecting the military situation are considered; where applicable, each element is considered bothfrom the enemy's viewpoint, and from our own.
16. CRITICAL TERRAIN FEATURES. As a resultof the study just indicated it frequently becomes clearthat a certain terrain feature, for example a dominant
hill or ridge, or an obstacle to mechanized attack, willbe critical in the contemplated operation, or that its
possession by either the enemy or by our own forces will
have a marked influence upon the operations of eitherside. If there is such a terrain feature, it should be
discussed briefly at this point; if there is not, a statement to that effect should be made.
17. TACTICAL EFFECT OF TERRAIN. This portion of the study should summarize the effect of theterrain on the immediate tactical or administrative
situation. Using a systematic approach, frequently it
is desirable to discuss separately the effect of the terrain
upon each enemy capability, and then to discuss in asimilar manner its effect upon each line of action
contemplated by our own troops.

24

CHAPTER 3
GENERAL FORTIFICATIONTECHNIQUE
SECTION ITOOLS AND MATERIALS
18. TOOLS. Tools normally used for hasty fortification work are carried by the infantry. These may besupplemented by additional tools obtained from en-

WIRE

CUTTERS

2F

SCALE
0

SHOVEL

2 FT.
I

2Figure 4. Entrenching tools carried by infantry soldiers.

25

O

I

SCAt.

PACKED IN CARRYINGCASE

FOLDED FOR CARRYINGFOR USE AS A PICEFOR USE AS A S1OV¥L

Figure 4-Continued.

26

2,

gineer supplies. Each infantry soldier carries a small
entrenching tool (fig. 4) on his pack. Standard-sized
tools are supplied in infantry entrenching tool sets

(figs. 5).

250

D-HANDLED25

PICK MATTOCKS

500 SANDBAGS
9 WIRE CUTTERS

13

26 SAWS

SCALE

3 FT.

Figure 5. Principal tools carried in infantry entrenching tool set.
19. MATERIALS. Materials for fortification are supplied through engineer dumps, and include antipersonnel mines and firing devices, lumber, barbed wire andpickets, and materials for reveting, camouflage, shelter
construction, and concrete construction. Antitankmines are supplied like ammunition.

SECTION II

GENERAL TECHNIQUE
20. CLEARING FIELDS OF FIRE. Suitable fieldsof fire are required in front of each entrenchment or27

emplacement. In clearing them the following principles must be observed:a. Do not disclose position by excessive or carelessclearing (fig. 6).
b. In areas organized for close defense, start clearing near main line of resistance and work forward atleast 100 yards.
c. In all cases leave a thin natural screen to hide defense positions (fig. 7).
d. In sparsely wooded areas, remove the lower
branches of scattered, large trees. Occasionally it isdesirable to remove entire trees which might be used as
reference points for enemy fire.
e. In heavy woods, complete clearing of the field offire is neither 'possible nor desirable. Restrict work tothinning undergrowth and removing lower branchesof large trees. In addition, clear narrow lanes for fireof automatic weapons (fig. 8).
f. Remove or thin thick brush. It is never a suitableobstacle and obstructs the field of fire.
g. Demolish other obstructions to fire, such as buildings and walls, only when resulting debris provides
less enemy protection.
h. Mow grain crops and hay fields or, if ripe anddry, burn them if it will not disclose the position.
Usually this is practicable only for a deliberate position
organized prior to contact with the enemy.
i. Drag away cut brush to points where it will not
furnish concealment to the enemy nor disclose theposition.
j. Before clearing the fields of fire make a careful
estimate as to how much clearing can be done in thetime available. This estimate often determines thenature and extent of the clearing to be undertaken, since28

ORIGINAL

WRONG -AFTERRIGHT-AFTERTERRAIN

IMPROPER

CLEARING

PROPER

CLEARING

Figure 6. Clearing fields of fire.

S6639-73

29

(IN FRONT OF NATURAL SCREEN)

0

RIGHT
(JUST BEHIND THIN NATURAL SCREEN)
Figure 7. Thin natural screen.

30

~~~~~~~~.
~~ ~

~

~

F

N~~~~~~
f,

m

0

4''

INZ

3

1

LL

03

2

m~~~

0~~~c--#:~~~~~I>4~ .

o~~~~~C31

zc-~~~~~~3

xi

0-

WL
0,

WI
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V~~~~~~~~

32
wW

,~~I

~~~L

w~~~

0

32

a field of fire only partially cleared may afford theenemy better concealment and cover than the area in
its natural state. Estimates may be based on table I,
which makes no allowance for the removal of debris.
Additional allowance must be made for this, depending
upon tile amount of debris, length of haul, and equipment. available.
TABLE I.

Man-hours required to clear 100 square yardsofDescription
le

aring

underclearing-clearing
Mediumgrowth and some trees not exceeding 12 inches in diameter.
Light clearing---clearing small brush
only.

Tools used

Ian-hours

required

Saws, axes-

3

Axes-

1

21. CAMOUFLAGE. Concealment is of prime importance in locating defensive works. Before any excavation is started, all turf, sod, leaves, or forest humus
is removed carefully from both the area to be excavatedand that on which spoil is to be piled. This material isset aside and replaced over the spoil when the work
is completed. To prevent discovery of the work during
excavation, camouflage nets are suspended from stakes
or trees before excavation is started. The workers confine their activities to the area beneath the camouflagenet. The net is suspended high enough above theground to permit excavation without snagging equipment or entrenching tools on it. After the excavation
has been completed and the spoil covered with sod orother natural camouflage material, the net is loweredclose to the ground so that it is inconspicuous fromground observation. Nets are kept in position when
the weapon is not being fired. Arrangements are made33

to withdraw or lift the net during action. For a more
complete discussion of camouflage, see FM. 5-20.
22. EXCAVATION. Excavation is usually by pickand shovel. The nature of the soil, tools available,
condition and experience of men, presence of the enemy,amount of light to work by, size of excavation, andweather conditions, all affect the rate of excavation.
Because of the large number of variables involved,
precise data cannmot be given. As a rough guide, it may
be stated that in medium soil, using standard size
tools, a man in good condition can excavate between 20
and 30 cubic feet per hour. Table II gives estimatesfor excavation of man-hours required to build thevarious types of infantry weapons emplacements described in chapter 4.
TABLE II.

Excavation and camouflage data for infantry weapons
emplacements
Man.

WeaponType of m-plaeoement

Area to be Excava- hour reeamution
quirodf aged(feot)(cubicfeet)

to on.ltruet
imedium
soil

37
37
'250

1%
1%

5x 5

50

3

fHorseshoe ___ 15 x 15
12 x 12l2-foxhole ....
fHorseshoe_ _ 15 x_ 18
3 foxhole-__15 x 15
Pit 14 x 14
.
do
do-_
.
...
16 x 16
Circular 21 x 21
29 x 29
Fan --------Rectangular
27 x 36
24 x 39
Fan Circular_- 29 x 29

123
74
140
11
70
108
110
195
550
410
430

7
3
8
5
4
6
5
10
28
21
22

10 x 10l_
FoxholeRifle----------------_
10 x 10
do Automatic rifle ---------'Pit-foxhole_ lx 10-Pit-foxhole
{287
0x 10
Rocket launcher

Pit--

Machine gun, light, cal.
.30.
Machine gun, heavy,cal. .30.
60-mm. mortar81-mm. mortar _-_.
.
37-mm. AT gun.----.--57-mm. AT gun
105-mm. howitzer M83*See chapter 4 for details of emplacements.

34

.....

t Without foxholes.

f432

I With foxholes.

23. DISPOSAL OF SPOIL. Excavated soil is muchlighter in color and tone than surface soil and must be
hidden carefully lest its presence disclose the fortifica-

SPOIL BEING REMOVEDCORRECTLYSPOIL BEING CONGEALED CORRECTLY
Figure 9. Diof spoil.

tion (fig. 9). Thereareseveral ways to dispose of spoil.
a. It may be used to form a parapet if the topsoil iscarefully saved and used to cover the parapet. Turf,35

sod, leaves, or other litter from under nearby bushes ortrees are used to make the parapet resemble its surroundings.
b. It may be removed and carefully hidden undertrees or bushes or in ravines. Care must be taken to
avoid revealing tracks.
c. It may be collected and used, partly camouflaged,
to form parapets for dummy positions.
24. DRAINAGE. Lack of proper drainage increases
the maintenance work and the hardships of the troops
occuping the fortifications. It must be provided for in
the lay-out and construction of all works.
a. Proper location. Proper location limits but does
not eliminate the drainage problem. If possible, lowpoints and drainage lines are avoided, and trenches arelocated on slopes (fig. 10). A slope of 1 percent causes
all water to run to the lowest part of trench, from which
it can be easily drained. Slopes exceeding 21/2 percent
cause erosion.
b. Surface and rain water. Surface and rain water
can be largely excluded by deflecting it through the useof small ridges (fig. 10) into ditches passed around thefortification, or over it by means of flumes.
c. Subsurface water. Surface water may be removed by the use of sumps or of drainage ditches (fig.
10) run to natural drainage lines from low points in entrenchments or emplacements. Sumps are located at
low points and emptied by bailing, siphoning, or pumping. They should be a minimum of 11/2feet square and
1 foot deep.
25. REVETM[ENTS. A revetment is a retaining
wall, or facing, for maintaining an earth slope at an36

I,~~~~~~~~~~~~~~~~~~~~~~~-

\\ \
z \0
ag~~~~~~~~~~~~~~~~~~~~~~~~~~~~'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'

~ ~~I
a

ab

e\

, ".'

<

d
37

\~ar4

\

\

\

\

\

Al Z F

'C

SiC

0,

angle steeper than its natural angle of repose. In all
but the hardest ground, when the position is to be occupied for more than a few days, some measures must
be taken to prevent crumbling of walls. Decreasing theslope for this purpose also decreases protection affordedby the emplacement and makes concealment more difficult. Revetments require considerable labot and material, but reduce maintenance and insure stability. Earthwalls in entrenchments and emplacements not only are
subject to normnal erosion processes and wear and tearof constant occapation, but also must withstand heavy
earth shock caused by explosion of bombs and artillery
shells. There are two kinds of revetment, the retaining-wall type and the surface or facing type.
a. Retaining-wall type. This type is self-supporting and acts by its weight. Dimensions of the excavation must be increased to allow space for this type of revetment.
(1) Sandbag revetment. These are particularly
useful for emergency work, for repairs, and on theinterior slopes of earth parapets.
(a) The standard sandbag measures 14 by 261/¼
inches when empty, and has a string attached 3 inchesfrom the top. When three-fourths full, the bag weighsfrom 40 to 75 pounds, depending upon nature andmoisture content of the filler. The average filled sandbag weighs about 665 pounds, and occupies a space 43/4
by 10 by 19 inches. The following data are useful inestimating the number of sandbags required for reveting
purposes:
1. If a single row of stretchers is used, as occasionally is done for small revetments,
about 160 sandbags are required for each
100 square feet of surface to be reveted.
381

2. If alternate headers and stretchers are used,
as is proper, about 320 sandbags are re:quired for each 100 square feet of surface
to be reveted.

SECTIONELEVATIONCHOKES AND SIDE SEAMS OUT(WRONG)SECTIONELEVATIONCHOKES AND SIDE SEAMS IN(RIGHT)ELEVATIONJOINTS NOT BROKEN(WRONG)ELEVATIONJOINTS BROKEN(RIGHT)ELEVATIONSECTION
ALL STRETCHERS(WRONG)ELEVATIONSECTION
STRETCHERS AND HEADERS(RIGHT)

Figure 11. Sandbag revetment.

3. If sandbags are used for fills, parapets, orbreastworks, about 195 are required foreach 100 cubic feet of fill.
(b) Ordinary sandbags should be used for temporary reveting only. Where bags are to be in place fora month or longer under average conditions of moisture,they must be rotproofed or filled with soil partially39stabilized with cement or bitumen. The latter method
usually is simpler in the field.
(e) Sandbags are laid as follows (fig. 11):
1. Fill bags uniformly about three-fourths full.
B. Tuck in bottom corners of bag after filling.
3. Build walls with slope 3 on 1 to 4 on 1.
4. Place bags perpendicular to slope.
D. Place bottom row headers.
6. Alternate intermediate rows as headers andstretchers.
7. Complete with a top row of headers.
8. Place side seams and choked ends on the inside.
9. Break joints and beat bags into place andinto rectangular shape with back of shovel,or tamp with feet.
(2) Sod revetment. Thick sod makes durable revetments. Sods are cut about 18 by 9 inches, laid grass
down, except for top layer, and pinned together withwooden pegs. The procedure given for sandbag
revetment applies.
b. Surface or facing revetment. Surface or facing
revetment must be supported, and serves mainly to protect the reveted surface from effects of weather anddamage due to occupation. Whlen strongly constructed,
it retains loose material. Its top should be about 8
inches below the ground level to prevent its being
snapped or damaged if tanks cross the reveted wall.
(1) Issue material. Issue material, such as burlap
and chicken wire, wire mesh, expanded metal (XPMA),
or corrugated iron, for this type of revetment may beobtained in limited quantities at engineer dumps.
These materials are held in place against the surface
to be reveted either by wooden pickets (at least 3
inches in diameter) or by issue steel pickets. Pickets
40

are driven into the floor and held at the top by holdfasts. In installing this type of reveting (fig. 12), thefollowing operations are necessary:(a) Cut grooves for pickets into wall to be reveted. Space 11/2 to 6 feet apart, depending upon reveting material to be used.
(b) Prepare holdfast in front of each groove.
Hold fast anchor picket should be from 8 to 10 feetfrom wall.

Figure 12. Installing burlap and chicken-wire revetment.
(e) Place two end pickets loosely. Stretch material between them and hold taut while end pickets aretightened.
(d) Drive all pickets at least 1V2 feet into floor andfasten tops to anchor pickets with two turns of No. 10
wire. Draw pickets tight by racking. Pickets draw
material tight against surface to be reveted.
(2) Natural material. Since issue material often
is difficult to obtain in the field, most reveting is done41with natural material such as brush and cut timber
obtained at the site.
(a) A brushwood hurdle (fig. 13) is a woven revetment unit usually 6 feet long and of required height.
Brushwood less than 1 inch in diameter at butt is woven
on a framework of sharpened pickets driven into theground at 18-inch intervals. When finished, hurdle is

6 F
Figure 13. Building a brushwood hurdle.

removed and carried to erection site where pickets are
driven into floor and held in place by holdfasts.
(b) Continuous: brush revetment (fig. 14) is constructed by driving 3-inch pickets at 1-pace intervals
about 4 inches from face of surface to be reveted.
Space behind the pickets then is packed with small,straight brush laid horizontally. Pickets are drawn
tight by means of holdfasts.
(c) Cut-timber revetment (fig. 15) is the principal
42

Figure 14. Continuous brush revetment.

pARAprrET
STRUTS

oaOUNO UNE
IN MEDIUMSOFT SO"L
LOWERPIT ONLYWILLREQUIREREVETMENT

SUMP

Figure 15. Cut timber revetment.

43

natural means o:F reveting foxholes and emplacements.
It is similar to continuous brush revetment, except thata horizontal layer of small timbers, cut to length ofwall to be reveted, is used in place of brush. Pickets® SANDBAG BREASTWORK
ENEMY

3'MIN:

ON

ION
4

SLO
GROUND@SANDBAG AND EARTH BREASTWORK-:3
MIN_.1 |ENEMY

GROUND

FigureLOG . BreST

or

STAKE

BREASTWORKRAND
LSGLG FENCE
FENCE
AND EARTH
EARTH BREASTWORK
Figure 14.
44

Breastworks (height varies).

are held in place by holdfasts or struts. When available, dimension lumber may be used in a similarmanner.
26. BREASTWORKS AND PARAPETS. Breastworks and parapets are built for protection when soil
conditions or subsurface water prevent excavation.
They also are used with dug in emplacements to saveextra digging. They ale built at least 3 feet thick at the
top to protect against caliber .30 bullets and againstshell fragments. Also, they should be free of loose
rocks and pieces of wood. Figure 16 illustrates various
types of breastworks.
27. PROTECTION AGAINST TANKS. So far aspracticable, entrenchments and emplacements are built
to provide protection against tanks. Rocks or otherpieces of hard material should not be left on or near thesurface of the ground within 3 or 4 feet of the lip of theentrenchment or emplacement. The pressure on such arock caused by a tank collapses earth walls which otherwise would be able to withstand the passage.

jTs;97'o-4~~~--~~45

CHAPTER 4ENTRENCHMENTS AND
EMPLA CEMENTS

SECTION I
GENERAL
28. EMPLOYMENT. a. It must become a habit of all
soldiers to seek protection from enemy fire, advantage
being taken of natural cover such as ditches or holes
in the ground. Whenever the situation becomes stabilized temporarily, they dig entrenchments for themselves and emplacements for their weapons. This applies to crews of all weapons; personnel guarding roadblocks, bridges, rear installations, and tactical headquarters; and troops in bivouac or assembly areas.
b. In all defensive situations troops are trained tostrengthen their positions and seek protection by theimmediate construction of hasty field fortifications.
c. In the attack troops are trained to drive forward
until the objective is captured and consolidated, taking
full advantage of all existing cover. Positive measures
are taken to insure that the momentum of attack is maintained. A change from the offensive to the defensive isa responsibility of command and is justified only whennecessary to avoid ruinous losses.
46

29. REQUIREMENTS. Entrenchments and emplacements must meet the following requirements:
a. Permit each individual or weapon crew to accomplish the assigned fire mission.
b. Be simple and easily constructed.
e. Provide maximum protection with minimum timeand labor.
d. Provide all-around defense.
e. Afford maximum concealment.
f. Provide protection against mechanized attack.

SECTION H
INFANTR Y ENTRENCHMENTS
FOR HASTY FORTIFICATIONS
30. GENERAL. Entrenchments are located to covera selected area with fire and, at the same time, provide
concealment from aerial and ground observation andprotection from enemy fire. These requirements are
met when the troops are located in one- or two-man foxholes as described in this manual. To confuse theenemy, judicious use must be made of decoys or dummy
positions.
31. FOXHOLES. a. General. Foxholes are entrenchments normally dug for individual protection when contact with the enemy is imminent or in progress. They
provide excellent protection against small-arms fire, artillery shell fragments, airplane fire or bombing, andthe crushing action of tanks. The one- and two-man
foxholes are basic types, the choice of type resting with47

the squad leader if not prescribed by higher authority.
The two-man foxhole is used when men must work inpairs or when, for psychological reasons, battlefield comradeship is desirable.
b. Use. For units within the battle position, foxholes are sited with the longer side generally parallelto the front, but they are distributed around weapofi emplacements to provide for all-around defense. Troops
occupy their foxholes only when an attack is imminent
or in progress. In some situations, where the need forrest is paramount, commanders may permit soldiers tostop excavation before full depth has been reached.
32. ONE-MAN FOXHOLE (fig. 17). a. Dimensions.
(1) The size and shape of the foxhole are affected by
the following:(a) It is as small as practicable, to present the minimum target to enemy fire.
(b) It is wide enough to accommodate the shoulders
of a man sitting on the firestep.
(e) It is long enough to permit the use of large-size
entrenching tools.
(d) It is at least 4 feet deep to the firestep, fromwhich the standing occupant should be able to fire.
(e) A sump is dug in one end for bailing out waterand for the feet of the seated occupant.
(2) The foregoing considerations result in the dimensions shown in figure 17. The soldier should memorize these simple dimensions: 2 feet wide, 31/2 feet long,
4 to 5 feet deep depending upon the height of the man,and additional depth at one end for the sump.
b. Details of construction. In most types of soil
the foxhole gives positive protection against the crushing action of tanks, provided the soldier crouches at least48

3' MI

ENEMY

.

N.

ADDITIONALDEITH

SPOIL FROM EXCAVATIONUSED TO CONSTRUOT ALLAROUNO
PARAPET.

PLAN

O

SPOIL

SECTION

Figure 17. One-man foxhole.

(Camouflage omitted.)49

2 feet below the ground surface (fig. 18). In very sandyor very soft soils it may be necessary to revet the sides
to prevent caving in. The spoil is piled around thehole as a parapet, 3 feet thick and approximately /2 footMINIMUM 2 FEET CLEARANCEREQUIRED TO PROTECT' AGAINSTTANK TRACKS

-.

, _

,~~

MINIMUM
CLEARANCE
2 FEET

Figure 18. One-mDan foxhole protects against tanks.

high, leaving a berm or shelf wide enough for the soldier
to rest his elbows upon while firing. If turf or topsoil
is to be used to camouflage this parapet, the soldier firstremoves the topsoil from an area 10 feet square and sets
it aside until the foxhole is completed.
50

c. Foxhole with camouflage cover.

It may bepracticable for the soldier to remove the spoil to an inconspicuous place and to improvise a camouflage coverfor his foxhole (fig. 19). This technique is especiallyeffective against a mechanized attack supported by footsoldiers. Riflemen remain concealed until the tanks
have overrun the position; then they rise up and combat
the enemy foot soldiers following the'tanks.

DETAIL OF CAMOUFLAGED

Figure 19. One-man foxhole waith earniouflalged cover.

33. TWO-MAN FOXHOLE (Jig. 20). The two-man
foxhole consists essentially of two adjacent one-man
foxholes. Since it is longer than the one-man type,
the two-man foxhole offers somewhat less protection
against tanks crossing along the long axis, as well as
against airplane strafing and bombing and artillery
shell fragments. Figure 15 shows a two-man foxhole
revetted in soft or sandy soil.
5134. INDIVIDUAL PRONE SHELTER. Prone shelters (fig. 21) seldom are dug in forward areas. They
may be authorized in rear areas when ground attack is
unlikely, or when the warning service insures sufficient
time to construct foxholes. The prone shelter, being
shallow, does not provide protection against the crushCAMOUFLAGED COVER,,/,

ONE -MANFOX HOLE® Figure 19--Continued.
ing action of tanks and is not suitable as a firing position.
The prone shelter gives considerable protection against
hostile artillery and aviation and against small-arms
fire.
35. CONNECTING TRENCHES. Connecting trenches(fig. 22) are conspicious to aerial observers and on52

aerial photographs, and thus reveal the defensive dispositions. Continuous connecting trenches are not dug
as a normalprocedure. When two forces are in contact
and dispositions have been revealed beyond any ques-Z

Figure 20. Two-man foxhole.

SPOIL FROM EXCAVATIONUSED TO CONSTRUCT ALLAROUND PARAPET(Camouflage omitted.)tion, a few short trenches may be dug in inconspicious
places to permit necessary daylight movement acrossexposed areas. Necessary connecting trenches also may
be dug in close country, such as jungle, where the posi53
53

tion probably will not be disclosed. Further, they may
be dug whenever the improved protection, control, communications, and supply outweigh the sacrifice of concealment.
36. OBSERVATION POSTS. When observers are located in exposed positions, they should be well protected
and concealed.

PARAPEPGROUNDLINE

LOW

E

DEPENDINGON
HEIGHTOFMAN

- 7r

eOUT
eVT[
SECTION® Figure 20-Continued.

a. Both the one-man foxhole (fig. 17) and the twoman foxhole (fig. 20) with camouflaged cover (fig. 19)
are suitable for use as observation posts.
b. The covered observation post (fig. 23), althougha good type, takes considerable time to build. Since
the overhead cover provides splinterproof protection
only, this type of observation post is valuable only whenwell concealed. It requires 21 cubic feet of excavation
per foot of length, or a total of 105 cubic feet per 5-footsection.
54

Figure 21. Prone shelter (not a fire trench).

SPOIL REMOVEDGROUND
LINE

PARAPET

2

I2

PARAPETSPOIL USED FOR PARAPET
Figure 22. Shallow connecting trench. (Camouflage omitted.)
55

2,,

W

MStlX
U

Uo

DL
Dz=

o
a

·

·6

g~N

i

d
.

if~~~~~

5a;~~~~

56~~m ~Z~~~~~~~
i.PC
OI

56i

a

w0

Q.

SECTION III
INFANTRY WEAPONEMPLACEMENTS
37. GENERAL. Because of their advanced positions,infantry weapons such as machine guns, antitank guns,
mortars, and cannon generally require emplacements forthe protection of weapons and crews, and foxholes toprotect personnel not sheltered in the emplacement.
Careful attention is paid to camouflaging emplacements
against both ground and aerial observation. Dummy
emplacements are constructed for deception. (Seetable II for an estimate of the man-hours required to
dig the emplacements described in this section.)
38. AUTOMATIC RIFLE. The automatic rifle isfired from a one-man foxhole and does not require
special emplacement.
39. CALIBER .30 MACHINE GUN (LIGHT). There
are two types of emplacements for this gun: the horseshoe type and the two-foxhole type.
a. Horseshoe type (fig. 25). (1) The gun is placedin firing position ready for immediate action. Lying
down, if exposed to fire, the crew first excavate about
l/2 foot beneath the gun and then a similar depth forthemselves, thus niaking an open shallow pit (fig. 24).
The spoil is piled around in a parapet.
(2) The emplacement is completed by digging out
a horseshoe-shaped trench, about 2 feet wide, along therear and sides of the pit, leaving a chest-high shelf to thecenter and front to serve as a gun platform (fig. 25).
57

···:~~~~~~*'. :'IGH G-BU
P~~~~~~~~HAV
Figur 24.Inital s:jg
er.0mcin eglnhrehetp
lgto

,

I

G-IT T
ealcmn o aiev)Cmulg mte.

58~~~~:.

GROUND LINE:
LIGHT MG-ABOUT 1t FTHEAVY MG- ITO Ik FTFigure 24. Initial stage in horseshoe type emplacement for caliber .30 machine gun (light or heavy). (Camouflage omitted.)58:'. .ALL AROUND'BERM ABOUT IFT WIDE.i-. ~i -

'I _

__

ENEMY
GiUN PLATFORM
3-FT

TRENCH 2FT. WIDE

LONG

CHEST HIGH

PLAN

SECTION
Figure 25. Horseshoe type emplacement for caliber .30 machinegun (light). (Camouflage omitted.)

59

The spoil is piled around the emplacement to form aparapet at least 3 feet thick and low enough to permit
all-around fire.
(3) This emplacement furnishes protection against
small-arms fire and shell or bomb fragments. In firm
soil, this emplacement offers protection against the
crushing action of tanks. In loose soil, logs about 8
inches in diameter, placed across front, rear, and sidesof the emplacement and embedded flush with the top of
the ground, help to make the emplacement resistant tothe crushing action of tanks. When tanks appear about
to overrun the position, the gunners pull the weapon to
the bottom of the trench at the rear of the emplacement
and then crouch down to either side.
b. Two-foxhole type (fig. 26). This emplacement
consists of two one-man foxholes close to the gun position. To lay it out, a short mark is scratched on the
ground in the principal direction of fire. On the rightof this mark a foxhole is dug for the gunner. On theleft of the mark and 2 feet to the front, another foxhole
is dug for the assistant gunner. The spoil is piled all
around the position to form a parapet, care being taken
to pile it so as to permit all-around fire of the weapon.
In firm soil, the two-foxhole type provides protection
for the crew and the weapon against the crushing actionof tanks. When ranks appear about to overrun the position, the gun is removed from the tripod and taken
into one foxhole, the tripod into the other. The gunnerand assistant gunner crouch in the holes.
c. Choice of type. As a firing position, the twofoxhole type is a little less flexible than the horseshoe
type, but it is easier to construct and more nearly tankproof than the horseshoe type. Therefore, the two-foxhole type generally is preferred.
60

40. CALIBER .30 MACHINE GUN (HEAVY). There
are two types of combat emplacements for this gun: thehorseshoe type and the three-foxhole type. In addition,
PRINCIPALDIRECTION
OF FIRESPOIL FROM FOXHOLESUSED FOR ALL-AROUND
PARAPETOXHOLE FOR

E

rASSISTANTGUNNER\

PLAN
Figure 26. Two-foxhole type emplacenment for caliber .30 machinegun (light). (Camouflage omitted.)

there is an antiaircraft type for use when the gun ismounted on elevator for fire against air targets.
a. Horseshoe type (fig. 27). This emplacement issimilar to the one described for the light gun (par. 39).
566397-- 5

61

The open shallow pit for the heavy gun (fig. 24) is
dug somewhat deeper, from 1 to 11/2 feet below groundlevel. Construction procedure is the same. This emplacement permits easy traverse of the gun through180 ° . To fire aimed shots to the rear, the gunner must
get out of the trench and sit on the forward part of'
the gun platform. In most types of soil, tanks can run
over this emplacement without destroying it, the'

.

·

.-

,

eq_

-I®

Figure 26-Continued.

-weapon, or the occupants. In loose soil, logs about 8
inches in diameter placed across the front, rear, andsides of the emplacement and embedded flush withthe top of the ground help to make it tankproof. Upon
the approach of tanks, the crew, without dismounting
the weapon from the tripod, move it to the rear into
the horseshoe trench and then crouch down to eitherside.
b. Three-foxhole type (fig. 28). The tripod legs
for the heavy machine gun are reversed when the62

GUN PLATFORM
WAIST HIGH

l

--

t

TRENCH ABOUTrAPET.
3F~.- "'WIDE

32FT -PLAN

SECTION
Figure 27. IHorseshoe-type emplacement for caliber .30 machinegun (heavy). Camouflage omitted.

63

weapon is fired from the three-foxhole emplacement.
This allows the dun to be mounted close to the gunner's
foxhole, which is immediately behind the weapon.
The assistant gunner occupies the foxhole to the left.
The third foxhole remains unoccupied until it becomes
necessary to fire the gun to the left, at which time the-1'ENEMY/R..,#'
W..
,.- F

. "

2

4-r

. it'.ISRVERSE
TR'#K OF G

PARAPET 3FTU THICK.' 'ALL AROUND'
:'

,8
w

_

Figure 28. Three-foxhole type emplacement for caliber .30
machine gun (heavy). Camouflage omitted.
gunner and the assistant gunner shift to the right(couterclockwise). The spoil is piled all around theemplacement to form a parapet, care being taken to
pile it so as to permit all-around fire of the weapon.
When tanks appear about to overrun the position, thegun is dismounted from the tripod and the tripod iscollapsed. One member of the crew takes the gun with
him into his foxhole; the other takes the tripod.
64

c. Comparison of combat types. In general, thehorseshoe type and the three-foxhole type of emplacement are both satisfactory. As a firing position, thethree-foxhole type is less flexible than the horseshoe
type, but in some soils it may be more tankproof. The
three-foxhole type has the advantage of using standard
foxholes. However, the horseshoe type permits the gun
to be restored more quickly to its firing position following a tank attack, since the gun remains on the tripod.
For the latter reason, the horseshoe type generally ispreferred for the heavy machine-gun.
d. Antiaircraft type (fig. 29). The caliber .30 heavymachine gun, provided with elevator, is emplaced ina circular pit about 4 feet in diameter at the bottom,
deep enough to provide protection and yet allow thegun to engage ground targets. It is used only where
defense against air targets is the primary consideration, as it does not provide the protection afforded by
the horseshoe and three-foxhole types.
41. 60-MM MORTAR EMPLACEMENT (fig. 30). a.
Open type. This consists of a rectangular pit large
enough to accommodate the mortar, the gunner, and theassistant gunner. The emplacement is kept to the minimum size to afford protection against airplane fire andbombing and against artillery shells, but it allows roomfor firing the mortar and storing necessary ammunition. The front edge is sloped so that the aiming stake,about 10 yards to the front, is visible through the sightand so the weapon's fire will be clear. The spoil fromthe excavation is piled all around the pit to form a low
parapet. Foxholes for members of the mortar squad
not required at the gun are prepared not far from theemplacement. Additional ammunition is placed in
nearby shelters.
65

SPOIL USEDTO CONSTRUCT
ALL-AROUND
PARAPET

PLAN
GROUND

PARAPET

LINE

3'
1ELEVATOR

4'

,I

SUMP

PROFILE

Figure 29. Antiaircraft empl:lcement for caliber .30 machinegun (heavy) with elevator. (Camouflage omitted.)

66

f ,'

F

a

3;

~.fr.-..

?"BEXCAVATIONABOUT 3 FT.

DEEP
SPOIL

PLAN

.

-*

iol.

Figure 30. Open emplacement for 60-mm mortar.
omitted.)(Camouflage67

b. Two-foxhole type (fig. 31). This shows the 60mm. mortar in action with only the base plate dug in,
the crew operating from one-man foxholes. This twofoxhole type of emplacement is preferred when the mortar is in defilade.
42. 81-MM MORTAR EMPLACEMENT (fig. 32).
Except for somewhat larger dimensions, this emplacement is the same as the open type described above forthe 60-mm mortar. A revetted ammunition niche may
be built into the side of the pit.
43. ROCKET LAUNCHER. There are two types of
emplacement for this weapon, the pit-foxhole type andthe pit type.
a. Pit-foxhole type (fig. 33 (0). This emplacement
is a circular pit, 3 feet in diameter and about 31/2 feetdeep, large enough for two men. It permits the assistant rocketeer to turn with the traversing weapon, sothat he is never behind it when it is fired. The emplacement is shallow enough to permit the rear end of therocket launcher at maximum elevation to be clear of theparapet, thus insuring that the hot back-blast from therockets is not deflected to the occupants. This emplacement is not tankproof. Therefore foxholes for thecrew are dug nearby. As the antitank.mission of thisweapon requires that it be kept in action against hostiletanks until the last possible moment, these foxholes will
be occupied oniy when a tank is about to overrun theemplacement.
b. Pit type (fig. 33 0). In firm soil the diameter ofthe circular pit (fig. 33 () can be increased to 4 feet andan additional circular pit 2 feet deep and 2 feet in diameter excavated in the center. This leaves a circular
68

.,!
I~~

S

·I

11/

i

i ii

/1r-

E~~

$t'S

i :··t~~~~.
· ~,~,.
Ct

r

*

69

ENEMY

1
ASOUT4

BERM IF 1 .
FP

e

.I

j-

,

'.

PLAN

AIMINGSTAIF ABOUT

-v

_

_

_

FRONTEDGEOF
EMPLACEMENT SLOPIITO CLEARLINE OF

SIGN? TO AIMINGSTAKEGUNNER!

SSISTANTABOUT GFTSECTION

Figure 32. 81-rum mortar emplacement.

70(Cauloutlage omitted.)fire step 1 foot wide and about 31/2 feet below the surface.
When tanks appear about to overrun the position, therocketeer- and assistant rocketeer crouch down into thelower pit. When the tanks have passed, the rocket
launcher quickly is returned to action.

·

:- ,

PERSPECTIVE

EMPLACEMENT

.:

,,.._

VIEW

NO FI

IS WAIST DEEPS POILEis..¥ '"-'~lil""'""~ .=''B ',FOXHOLESR
EMPLACEMENTF OXHOLEFIRESTEPFOXHOLEPLAN

ID Pit-foxhole type.
Figure 33. Emplacements for antitank rocket launcher.
(Camouflage omitted).
71

I

I

$

NOTE:

1,"SPOIL.......
¾-_

./9

2'

SECTION() Pit type.
Figure 33-Continued.
79

REMOVED44. 37-MM ANTITANK GUN EMPLACEMENT. For
this weapon there are three standard types of emplacement, each adapted to a special situation. For flat terrain the circular emplacement (fig. 34) is preferred,since it permits all-around fire. For sloping terrain

NOTE:
PITS FOR WHEELS AND
FOR BARREL ARE DUG.
PLAN
WHEN NOT FIRING,GUN
IS PLACED IN THESE
PITS SO ASTO BE BELOWLEVEL OF PARAPETGUN CLEARS PARAPET
ALL AROUND

ARAPTGROUND_-r\NI LINE

SECTIONO
Figure 34. Circular type emplacement for 37-mm antitank gun.
(Camouflage omitted.)73the rectangular-pit emplacement with ramp (fig. 35) ispreferred, since it gives partial defilade and protection
against ground observation. When the direction ofenemy approach can be foreseen definitely, as in covering a road block in a defile, the fan type emplacement(fig. 36) is preferred, since the gun can be fired instantly
without being moved from the cover position.

Fi-gure

.

ontr-

d.

Figure 34-Continued.

a. Circular type emplacement (fig. 34). This emplacement consists of a circular pit, 11 feet in diameterand 1 foot deep, measured from ground level, with an
all-around parapet 4 feet wide and approximately 9
inches high. The banks should be sloped so that the
gun can be moved into and out of the emplacement.
Pits for the wheels and a slit in the parapet for the gun
barrel allow the gun to be lowered below the parapet
when not firing, at which time the crew takes cover innearby foxholes. An ammunition pit may be dug inthe center of the emplacement or into the parapet. Additional ammunition is placed in nearby shelters. The
gun is maneuvered quickly to fire ini any direction byelevating the barrel, lifting the trails, backing the gun74

to the center of the emplacement, turning it in the desired direction, and pushing it forward against thebank.
b. Rectangular pit type emplacement (fig. 35)'.
This emplacement consists of a rectangular pit 10/2
feet wide, by 14 feet long, and 31/2 feet deep. To get the
gun into and out of the pit, a ramp is dug either straightout of the pit or at an angle thereto, depending upon the
sector of fire assigned to the gun. If the ramp is turnedat an angle to the pit, the elbow is curved so that the
gun can be moved around the corner. The gun isbacked into the rectangular pit, when not in firing position. The spoil is piled alongside the excavation toform a parapet. Several foxholes may be dug inside
the emplacement without interfering with the movement of the weapon. Additional foxholes are dug
nearby for the remaining members of the gun crew.
e. Fan type emplacement (fig. 36). This type of
emplacement permits little traverse but great speed ingoing into action. The ramp is to the rear of theemplacement.

45. 57-MM ANTITANK GUN EMPLACEMENT. Figure 37 illustrates the basic type of emplacement for thisweapon. It permits fire through an are of approximately 1100, and even more if protection is sacrificed
by modifying the parapet. The ramp normally is inrear of the emplacement, but it may be to the front if
terrain conditions require. The spoil is piled on bothsides of the emplacement to form a parapet approximately 21/2 feet high and 3 feet thick. Foxholes forthe gunner and the assistant gunner are dug within theemplacement. Additional foxholes for other membersof the crew are dug nearby.
75

PERSPECTIVERAMP
FIRINGPOSITIONII -(I 3FT MIN.

DEPTH

2'TO$

3FT.
,

/FOXHOLE

P

X"*

SPOIL
USED TOCONSTRUCT
PARAPET

PLAN

COVER POSITION

Figure 35. Rectanglnar pit type emplacement for 37-mm antitank gun. (Camouflage omitted.)76

PERSPECTIVE

VIEW

LAY-OUT STAKESPOIL PILED TO
FORM PARAPET

RAIMP

EXCAVATIONFOR GUN IS
hI FT. DEEP

PLAN
Figure 36. Fan type ermplaceneint for 37-mm antitank gun.
(Camouflage omitted.)

566397M'4-*677

46. 105-MM HOWITZER M3 EMPLACEMENT. Figure 38 illustrates a circular emplacement, 19 feet indiameter, permitting all-around fire. The pit is dug

Figure 37. Fan type emplacement for 57 mm antitank gun. (Camouflage omitted. Excavation is 2 feet deep.)about 2 feet deep and the spoil is piled in a low parapet
all around the emplacoment. A ramp is dug to therear. Foxholes for members of the crew are dug
nearby.
78

PERSPECTIVE VIEW

AMMUNITION

PLAN
Figure 38. Emplacement for 105-mm howitzer M3.
emitted.)(Camouflage

79

SECTION IV
SPECIAL AND STANDARD
TRENCH
47. SPECIAL TRENCH. a. Purpose. To meet theneeds of the field artillery the special trench (fig. 39)
has been developed. Where several men must be provided protection within a limited area, special trenches
frequently are used because they take less space thanfoxholes. Because they are especially suitable for use

PLAN OF 'Yi

PLAN OF 'CHEVRON'

PARAPETRARAPETLNE

Xi

CROSS-SECTION

NOTE: LEGS OR BAYS ARE 6FT. OR LESS IN LENGTH

Figure 39. Cross section and typical plans of special trenchused with artillery emplacements.
80(Camouflage omitted.)under a camouflage net, they normally are constructed
and occupied by artillerymen and by personnel at rear
installations.
b. Construction. The special trench is 2 feet wide,or less, and from 3 to 5 feet deep. It is dug in shortlengths, in the shape of a chevron, a Y, or any other
5

1

4
en

' ~

,, S5'-

PARAPETI',;~GROUND LINE

POITIONP ARAPETTRENCH

BOARD

M3

PARAPE'
tillery"IN.

dj

GRO U2ND

T.

ELBOW REST__STAGGEREDOTH SIES

Figure 40. Standard trench.

trace which fits into the space available. Changes in
direction are made to reduce the effects of bombs, artillery shells, or aerial strafing.
48. STANDARD TRENCH. a. Purpose. The standard trench (fig. 40) offers. much less protection, isharder to conceal, and requires more time and labor
to construct than foxholes. However, it improves com81

. I

._. ~

2

:~~~~~~~~~~~~~~~~~L

)?

1

0

:

'

$'

z

YZ~,

,".~'~:.(t"~~9-

0

EL

I

U~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-dmunication, control, supply, and evacuation. The useof trenches is a command decision. Standard trenches

might be used to advantage in the following situations:82

(1) Communication trenches in stabilized situations
where either concealment is available 6r the advantages
to be gained justify exposure.
(2) Entrances to shelters or groups of shelters.
|- s"',".
'"OR 'I4

OFFSET

CROSS SECTIONOFSTRINGERSPROVIDES FOROVERLAP AT

OUTER EDGE OF CROSS PIECES
4"FROM END OF STRINGERSJOINT
12" OR I'k4'

6'-6-

0-

1OVERLAP--

SIDE ELEVATION

2

k4"

4'

SIDE ELEVATIONEND ELEVATIONOF SUPPORTOF SUPPORTFigure 41. Detail of trench board and support.

(3) Qperations in extreme cold, where the soldiers,
who remain in heated shelters until the last minute,must be able to get to firing positions under cover.
83

(4) In jungle and forest warfare, where movementof tanks is impossible or very restricted and where
there is concealment from all types of enemy observation, particularly aerial photography.
b. Construction. The standard trench (fig. 400)
is 4 feet wide at the top, 2 feet wide at the bottom, and
512 feet deep. The spoil is used to construct an irregular parapet 3 feet wide on each side of the trench. To
aid in concealment, the trench is irregular in plan (fig.

40@) and is built in short sections.

Trench boards(fig. 41) should be installed in all standard trenches.
Lumber or cut timbers may be used. The trench is
deepened so the top of the trench board is 51% feetdown, and the bottom of the trench is shaped into a
trough for drainage. In soft ground, supports forflooring are required.
e. Fire positions. The standard trench is usedeither as a fire or communications trench. Fire positions (fig. 40) are staggered 5 to 10 yards apart on bothsides of the trench. They are dug 2 feet -wide, 21/2 feet
into the trench wall, and deep enough so the groundline is chest high. Fire positions are constructed in all
standard trenches both to increase combat effectivenessand to prevent the enemy from distinguishing between
fire and communication trenches.

,SECTION V
FIELD ARTILLERY
EMPLA CEMENTS
49. GENERAL. a. This section is a guide tothe construction of protective works for field artillery weapons
and personnel. Field artillery filed fortifications provide protection for84

(1) Individuals and small groups such as observers,
command post personnel, the battery executive, switchboard operator, and others.
(2) Ammunition.
(3) Gun crews.
b. Fortifications are planned to(1) Permit delivery of fire within prescribed zones.
(2) Permit direct laying against tanks.
(3) Take advantage of ground formations to lessen
labor.
(4) Take advantage of natural cover and'concealment.
(5) Allow the piece to be moved quickly to an alternate position.
(6) Provide personnel protection against artillery
fire and air bombardment.
(7) Be simple enough to construct with minimum
effort and time.
(8) Provide comfort during prolonged occupation.
c. Fortifications are begun as soon as practicable
after positions have been selected. They are so planned
that their progressive improvement is possible, using
tools and materials supplied in tables of equipment,
supplemented only by such additional material as islocally available. It should not be assumed that theoccupation of a position may be so brief that fortifications are unnecessary.
50. PRIORITY OF CONSTRUCTION. a. On going
into position, work is done to gain the following results,
listed in their general order of priority:(1) Ability to deliver fire on time.
(2) Concealment.
(3) Protection of personnel and ammunition.
85

(4) Alternate firing positions. Sometimes thismay be third priority.
(5) Other protective measures.
b. The following is an example of the procedure followed by a 105-mm howitzer section in daylight occupation of a previously selected position:(1) Place the piece in firing position, prepared for
all-around fire if required; lay the piece and otherwise
prepare to execute fire missions. Concealment is taken
into account in selection of the position, and continuously thereafter.
(2) Construct necessary camouflage.
(3) Dig entrenchments for personnel and shelters
for ammunition.
(4) Repeat above procedure for alternate positions.
51. PROTECTION FOR PERSONNEL.

Standard

types of entrenchments are employed for protection
against aerial and artillery bombardment as well as
possible ground attack.
a. Personnel at supply points, in bivouacs or assembly areas, and at installations other than gun emplacements are best protected in foxholes (par. 31) or prone
shelters (pair. 34).
b. Personnel at gun emplacements may utilize special trenches (par.. 47).
e. Personnel employed as observers occupy modified
foxholes or covered observation posts (par. 36).
d. In stable situations personnel protection may be
increased by constructing appropriate shelters (ch. 5).
52. AMMUNITION SHELTERS. The constructionof ammunition shelters begins as soon as the battery has
prepared for firing and is concealed (par. 50). Shelters86are so located and constructed that they are well concealed, protect ammunition against hostile fire and theweather, and contain the quantities desired near where
they are to be used. Usually projectiles, powder charges,
fuses, and primers are stored in separate shelters, atleast two shelters for each item, so that a direct hit
cannot destroy all of any one of them. The protection
required for the several components of separate loading
ammunition is the same as for complete rounds of fixed
or semifixed ammunition. The following methods are
employed:a. Initially, or where ground conditions limit excavation, ammunition is placed in natural depressions
and dispersed in relatively small quantities.
b. Pits may be hastily dug, and branches or rocks
placed at.the bottom to prevent contact of ammunition
with wet earth.
e. Time permitting, appropriate shelters may beconstructed. Representative shelters for 105-amm and155-mm ammunition are shown in figures 42, 43, and 44.
For further data concerning the storage and protectionof ammunition in the field, the quantity of ammunition
per shelter, and distance from other shelters required
to localize effects of a direct hit, consult the appropriate
Field Manual or Technical Manual for the weapon
concerned.
(1) Shelters in parapet of emplacement. Shelters
constructed and concealed in emplacement parapets(figs. 42 and 43) are convenient for ammunition handling, inconspicuous, and also keep ammunition dry.
(2) Open-pit type (fig. 44). This shelter consists ofa pit for handling and a shelf for stocking ammunition.
Similar shelters may be used in battery dumps.
8753. ANTIAIRCRAFT EMPLACEMENT FOR CALI.
BER .50 MACHINE GUN, AIR-COOLED (fig. 45).
This is a circular pit, 9 feet in diameter and of such
depth that the weapon can engage ground targets.
PARAPETGROUND LINE

SAND BAGS
1-' _'J:
1DROP CURTAIN(PAULIN)

SAND BAGS
2'~

I

1

I

FLOOR LINE Or

i , fEMPLACEMENT

3i

CROSS SECTION

fDSAND B-L

4 DIA.
DIA. LOGS
LOGS?
6"

__

--

FLOOR LINE OF
EMPLACEMENTLONGITUDINAL SECTION
Figure 42. Ammunition shelter in parapet.

(Camouflage

omitted.)54. EMPLACEMENTS FOR 105-MM AND 155-MM
HOWITZERS AND 4.5-INCH GUN. Standard emplacements for all models of 105-mt and 155-mm how88

itzers and the 4.5-inch gun are so constructed that thesame emplacement is suitable for any of these weapons.
The standard emplacements for these weapons are of
ND.L1\'D

ROP CURTAIN
BAGS

SAND
GR

|<i

' LOGSi,\| FLOOR LINE OF

?.

l' i,

l~

LOG

mEMPLACEMENTCROSS SECTION.SAND BAGS,
4t'DIA.LO
DIA

,- -

2i
_I[

t

-

LINE D-,FLOOR LINE OF{£~EMPLACEMENT',SUMPLONGITUDINAL SECTION
Figure 43. Ammunition shelter in parapet with handling pit.
(Camouflage omitted.)

two types: the surface type and the 24-foot-diameter pit
type.
a. Surface type emplacement (fig. 46). This consists of a built-up parapet of earth or sandbags in front
89

ENEMYGROUND LINEI ON 4 BATTLOSSECTION ON LINE "A-A

2

ENEMY

aUPNOTE:SECTION ON LINE.B-B FOR 21 ROUNDS-4
A

42 ROUNDS-B'

PLAN

Figure 44. Open-pit

type

ammunition

omitted.)90

shelter.

(Camouflage

of the piece, an ammunition pit on its left side, andspecial trenches to accommodate the gun crew. Special
trenches for six men usually are provided on the left ofthe piece and for two on the right.

APPROX. LIMITOF SPOIL

A20'

SP
IAL

*POX.2TR&NCH

PLAN
3' MIN ATTIHETOPSAPLING MAT
COVERINGGROUNDLINE

SECTION
Figure 45. Antiaircraft emplacement for caliber .50 machine gun,
air-cooled. (Camouflage omitted.)b. 24-foot-diameter pit type emplacement (fig.
47). This consists of a circular pit, approximately 2
feet deep and 24 feet in diameter, with a sloping ramp at91

the rear to get the piece into and out of the emplacement.
The emplacement is surrounded by a parapet approximately 11/2 feet high except at the ramp, which usuallyis left open to permit rapid withdrawal of the piece.
Ammunition shelters of the type indicated in paragraph 52 are located in the parapet on either side of the

P.RtPET_______Is. APPROX.

.WUNITIONPIT,%PIO HAseI$PCIAL TRNkCH

4

teNcn

SPSPCOIL

NREC-CNOTE
Spol from spycel trenches andammunition
pt used r prapet
It snd bap weu2sd fa parpe
lengith paraped
sos to pod.
moreprotecion fo special

Irence&Figure 46. Surface type emplacement for 105-mm and 155-mm
howitzers (all models) and 4.5-inch gun. (Camouflage omitted.)piece. To save extra digging after the parapet is completed, covered special trenches, located under the parapet, are constructed either prior to or at the same timeas the main pit. Spoil from the main pit, the ammunition shelters, and the special trenches is used to build
the parapet.
92

SPECIAL TRENCH
6' DEEP

4I\ .S

PLING-MATI

COVERING

PANDLING

5

SPECIAX
SPECUL3REN
TRENCH10NT

I LIMITS OFFENSHELTERPLACEMENT, THE WEAPON MAY BE SWUNGAROUND TO FIRE TO THE REAR OR IN ANY
DESIRED DIRECTION (FOR ALL-AROUND DE-

PARAPET

\

_8APP

¢

5697TIL

SPECIAL
TRENCH

N

G

ROUND
LINE

THE AXLE I IN THE CENTER OF THE EM-93

SECTION THRU RAMP

Figure 47. The 24-foot-diameter pit-type emplacement for 105-mm
and 155 mm howitzers (all models) and 4.5-inch gun. (Camouflage omitted.)

506s3

0

-4~4-----

9355. EMPLACEMENTS FOR 155-MM GUN.
a.
There are two similar types of emplacements, one for the
155-mm gun M1 (fig. 48) and the other for the 155-mm

APPROX. LIMITOF SPOIL_ UMP

HHNDLNS PT. Ml.-.to/

AeMMUNITON
I

SHELrERRAMP 0[ \ TREliCH E

SPECIAL TRENCH 6' DEEP
SeArPING-MA

70' APPROX

-

PLAN
_~

Lo3' MIN.

GROUNDSU--HANDLING PITSECTION THRU RAMP
Figure 48. Emilacement for 155-mm gun M1.
omitted.)(Camouflage

gun M2, M3, or modified GPF (fig. 50). The only
difference in the general iny-out and construction ofthese two emplacements is that the emplacement for94

the M1 gun is somewhat larger and has no recoil pit.
An alternate emplacement is required if it is necessary
to cover a greater sector of fire than that provided
by normal traverse in the emplacement.
b. Each of the two type emplacements is a fanshaped pit about 2 feet deep, with a ramp at the rear.

Figure 49. Lay-out of emlplacement for 155-rmm gun MI.

Ammunition shelters are located in the parapet on
either side of the piece. Covered special trenches t6
accommodate the gun crew also are located under theparapet. The parapet and ramp are built as describedin paragraph 54b above.
e. The outline of the emplacement is marked out on
the ground, as indicated in figure 49 for the M1 gun,95

LIMIT OF SPOILAMMUNITIONTAMMUNITIONSHELTERHANDLING PIT .1
· h

SSUMP

\

SPECIALRMP
E , DOWN',s)S~sRENCHCHSAPLING-MAT

PLAN

MRAPET,/3' MIN.
I-_ ' \GROUND LINE

SECTION THRU RAMP
Figure 50. Emplacement for 155-mm gun M2, MS3, or modified
GPF. (Camouflage omitted.)

and in figure 51 for the M2, M3, or modified GPF. The
center line of the emplacement is along the principal
direction of fire of the weapon, which is indicatedbefore lay-out and construction of the emplacement arestarted.
96

56. TRAIL SUPPORTS (fig. 52). Trail logs facilitate traversing the 105-mm howitzer beyond its normal
limits. They are especially desirable if wide-angle or
all-around fire is necessary. Except in wet or soft
ground during continuous firing, the 155-mm gun and

Figure 51. Lay-out of emplacement for 155-mnY gun M2, M3, ormodified GPF.

howitzer require no trail support beyond that affordedby the trail spade. This support is provided by placing
a large log or timber under the shoe perpendicular to
the trail. The timber should be 12 inches square and
12 feet long, extend 6 feet on each side of the spade,and be flush with the ground surface.
9757. WEAPONS PLATFORM (fig. 53). If timber isavailable, an improvised log platform may be constructed by burying three or four sills in the grounde. DIA.

ITRAIL

GGROUNDGROU D LIN E
a6"D~iA. TtMB
TIM·

g

4"

Figure 52. Detail of trail supports for 105-mm howitzer.

parallel to the direction of fire, and laying upon themat right angles, a row of straiqht logs. These can beheld in place by wiring or spiking the top layer to the98sills, or by covering the entire platform with 6 inchesof earth. The top of the completed platform should
be flush with the ground on either side.
LOGS WIREDTOGETHERLOGS LAIDRALELTO LINE OF FIRE

Figure 53. Gun platform for 105-mm howitzer.

SECTION VI
ANTIAIRCRAFT AR TILLER Y
EMPLACEMENTS
58. GENERAL. This section is a guide for constructing protective works for antiaircraft guns, personnel,
and mat6riel. Such construction takes several hours.
So that it can be done in an efficient and orderly manner, certain parts of the work are given priority.
Highest priority always is given to the mission. Whenever possible, for purposes of secrecy, new positions
are constructed and occupied during darkness, allcamouflage being completed before dawn. The following outline gives, in general, the procedure to be followed in fortifying a position.
99

a. Emplace materiel realy for firing as soon as possible. If the position is to be excavated, materiel is
emplaced off to the side of the final positions.
b. Dig foxholes or special trenches near the emplacement for personnel.
c. Provide hasty camouflage, if working in daytime.
d. Make necessary excavation at final position.
e. Emplace mat6riel in final position with minimum
interference to mission, and put in firing order.
f. Continue to build up and fortify the position astime permits.
59. REQUIREMENTS. a. While it is desirable togive every protection to personnel and equipment, theprime consideration always must be the efficient use of
the equipment. A typical fortification for antiaircraft
mat6riel embodies the following features:(1) A parapet 3 to 4 feet high surrounding the emplacement. The parapet should be at least 3 feet wideat the top, and its outside slope should be from 30' to
45 °. See tables XXIII and XXIV for required thickness for different materials.
(2) An inner diameter of the absolute minimum
permitting efficient operation. The inside walls should
be made as steep as the soil permits, preferably a slopeof 12 on 1.
(3) An inside depth permitting the gun or instrument to depress to its minimum elevation. If the guns
are located on level ground or at the bottom of a valley
where all targets must be above the horizontal, theparapet can be built to trunnion height.
(4) Barrel stops preventing fire into adjacent units.
(5) Provisions for drainage.
100

b. In stabilized situations it is desirable to remove
the wheels of the 40-mm gun to a place of greater safety;
but if the situation is such that the fire unit may haveto move at a moment's notice, this cannot be done.
Sandbagging the wheels is advisable, provided it does
not interfere with operation of the weapon. Also, instabilized situations the bogies of 90-mm guns are removed, provided a draw bar is available for the purpose. If they are not removed, they should be covered
with sandbags for their protection.
60. SHELTERS. a. Personnel. Normally, protection is required against blast and splinters of shells andbombs and penetrati6n of small-arms bullets. Suchprotection is obtained by dispersion and concealment
and by use of foxholes (par. 31) or special trenches(par. 47) located, in the immediate vicinity of theemplacement.

b. Ammunition. (1) Some ammunition is storedin niches in the parapet of the emplacement. Frequently ammunition cases buried in the parapet, with
open ends flush with the inside face of the parapet, areused for this purpose; or types of shelters similar to
those described in paragraph 52 may be used. A suitable cover must protect live ammunition from being
struck by ejected shell cases.
(2) The bulk of the ammunition carried by the gunbattery is stored in battery dumps. Usually two arebuilt per battery.

Where time is limited an open-pit

type of ammunition shelter may be used. (See par.
5 2 c(2).) However, shelters with 3 feetor more ofoverhead cover are better. A trench or pit covered by
8-inch or larger logs and earth is one suitable type. A
cut-and-cover shelter, similar to the one shown in figure101

86, may be used both as an ammunition shelter and to
store extra equipment. A trench or sandbagged passageway with at least one right-angle turn to retard
blast effect should lead to the entrance of the shelter.
61. GUN BATTERY EMPLACEMENTS. a. 9 0-mm
antiaircraft gun Ml on MIAI mount (fig. 54Q).
Unless it is possible to prepare the emplacement aheadof time, the emplacement for the gun on the M1A1
mount is built in two stages: first, the main pit, ramp,
and outrigger trenches are excavated; the gun is thenemplaced, leveled, and prepared for action; second,
parapets are built and, when necessary, revetted; ammunition niches are provided; outriggers covered; andthe ramp closed off. Note that-(1) The outrigger trench is covered to prevent a
break in the parapet, and yet in a manner to permit
ready withdrawal of the outriggers. It is overlaid withbrush or boards and covered with dirt in sufficient depth
to make a continuous parapet around the gun.
(2) Protection is furnished in the ramp by a wallof sandbags or a reverted dirt wall that can be readily
removed.
(3) Four ammunition niches are provided. Each isformed by plac ig four boxes of ammunition in the parapet with ends flush with the inside wall and then removing the exposed end of each box.
(4) A shor:t tunnel is built in the parapet for the
power transmission cables.
b. 90-mm antiaircraft gun M2 on M2 mount (fig.
54<)). The emplacement for a gun on the M2 mount issimilar to that for one on the MAl1 mount described ina above, except that it is somewhat larger, has a ramp
at either end, and has a greater inside depth.
102

c. 4.7-inch antiaircraft gun M1 on M1 mount (fig.
540). The emplacement for the 4.7-inch antiaircraft
gun is similar to that for the 90-mm gun M2 on mount
OUTRIGGER TRENCHMUST SE COVERED TOAPREVENT BREAK IN THE
PARAPET AND YET PERMIMMUNTINNICHE FOR 4 BOXE
(4ROUNDS EACn)

.:.

D I

CONSTRUCT AN
AROUND pARAPE

SECTIONB-REMOVABLE SANDBIAG

4DRAINTOPLAN

THRU PARAPETGROUNDSANDBAGSPARAPET

SUMP(

GROUND LINE

SECTION 'A-A'RA

90-mm antiaircraft gun M1 on MlAl mount.

Figure 54. Gun battery emplacements.

(Camouflage omitted.)
103

M2. Basically, it is a circular pit 22 feet in diameterand 6 feet 3 inches deep from the top of the parapet.
The pit is provided with niches for the side outriggers
and with two ramps for the front and rear bogies.
2

COVEREDAMMUNITIONNICHE CONTAININ,_

FOUR BOXES

PLACE

AT
-- +

U

EO6

MDrE:

MATERIEL REMOCOMPRDPLANSANDBAGSSECTION 'A A
THRU AMMUNI'ION NICHE
Oi

9,16' TO CENTER
OF EMPLACEMENTSECTION 'B B"
THRU OUTRIGGER TRENCH

0-mm antiaircraft gun M2 on .M2 mount.
Figure 54-Continued.

104

d. Power plant M7 (fig. 55). The emplacement for
the M7 power plant is a rectangular pit 91/2 feet long,
81/2 feet wide, and 6V/2 feet deep from top of parapet tobottom of pit. An extension should be connected to the
FOURBOXES EACH, PROJECTILESLOPE RAMP I ON
? AND PROPELLING CHARGE,
BOGIES ROLLED INTORAMP, BLOCKED. STORED UNDER BOGIES ANDIN
AND COVERED.
OTRJGGER TRENCHES.

OUTRIGGER TRENCHES
COVERED OVERAFTERGUN IS EMPLACED\NOTE: REMOVABLE SANDBAG
BREASTWORKS MAY
BE PLACED AT THE
ENDS OF THE RAMPS.

/

I- 'A"THIS SECTION MUST
BE REMOVED TO
WITHDRAWMATERIELDETAILTHRUOUTRIGGER
TRENCH--18' TO CENTER-) 4.7-inch antiaircraft gun M11 on M1 mount.
Figure 54-Continued.

exhaust'to carry the fumes out of the emplacement. The
transmission cable is buried, as indicated in n below.
e. Director M4 or M7 (fig. 56(D). The emplacement for the M4 or M7 director is a circular pit about 8
feet in diameter and deep enough to protect operating105

personnel while allowing full use of the director telescopes at low elevations.
f. Director, M9 or M10. (1) The tracker for theM9 or M10 director must be located in the open. Its

SPOIL USED TO
CONSTRUCT ALLAROUND PARAPETPLAN
REMOVABLE
BREASTWORKGROUNDLINE

SECTION

Figure 55. Emplacement for power plant M7.
omitted.)(Camouflage

emplacement is a circular pit just large enough to accommodate the tracker head with seats attached. Except for depth it is about the same size as the pit for106

the M7 director (fig. 56Q). It is less deep since thetelescopes are mounted lower.
(2) The traileris emplaced in a rectangular pit 16
feet long, 10 feet wide, and 8 feet deep (fig. 56®).

SPOIL USED TO
CONSTRUCT ALL*AROUND PARAPET

PLAN

GROUND LINE
*MIN~

~

PARAPETCABLE

SECTION

SUMP®o Emplaeement for director M7 or 14. (Camouflage omitted.)
Figure 56.
g. Height finder Ml or M2 (fig. 57). The emplacement for the height finder is a circular pit 10 feet indiameter and deep enough to allow the ends of theheight-finder tube just to clear the top of the parapet.

107

h. Height finder SCR-547 (fig. 58). The emplacement for the SCR-547 radio height finder is a pit large
enough to accommodate the trailer. There is provision
for swinging the outrigger jacks into position, and at
one end of the pit is a ramp for removal of the trailer.
This ramp is closed off with a sandbag parapet.
i. SCR-268 (fig. 590). In emplacing the SCR-268
care must be taken that the outside of the parapet is

REMOVABLe
BREASTWORKTO CLOSEENTRANCE.

3j.FT.CLEARANCETO SWINOO

4I~FT.

CLEARANCE TO
CONNECT CABLES

24-FT. CLEARANCE TO PASS FROMFRONT TO REAR OF TRAILERINSIDEHEIGHT TO BE a FT.

®)Emplacement for M9 or M10 director trailer.

(Camouflage

omitted.)Figure 56-Continued.

circular, so that it will have a constant effect on the elevation antenna.
j. SCR-545 (fig. 59(g). The SCR-545 is emplacedin a rectangular pit 30 feet long, 16 feet wide, and 8 feet
4 inches deep from the top of the parapet. These dimensions allow a 4-foot clearance on all sides for necessary
servicing.
k. SCR-584 (fig. 59(). The SCR-584 is emplacedin a rectangular pit 25 feet long, 14 feet wide, and 10 feet
4 inches deep from the top of the parapet. These
dimensions allow a 4-foot clearance on the back and the108

two sides, and a 1-foot clearance on the front fornecessary servicing.
I. BC scope. The emplacement for the BC scope issimilar to that for the searchlight control station shown

SpoIL_USED TO
CONSTRUCT ALL
AROUND PARA

PLAN

PET
GROUND LINE
PARAPETMINSECTION
Figure 57. Emplacement for height finder M1 or M2.
flage omitted.)(Camou-in figure 64. It is a circular pit just large enough toaccommodate the instrument and manning detail, andof a depth that does not obstruct the view at low angularheights.
566397°4----8109

m. Machine guns. See paragraph 40.
n. Cables. For protection in static positions transmission cable may be buried in a shallow trench. A
trench of the shape shown in figure 60 is best since it
provides drainage away from the cable. If freezing is
SANDBAG WALL ACROSSREAR PLATFORM FOR
ADDEO PROTECTION,

24'

REMOVABLE
BREASTWORKTO CLOSEENTRANCE

4-FT. CLEARANCE TO
PERMIT REPAIR OF
RANGE CONVERTER
UNIT

2-Ft CLEARANCE TO
OPERATE JACKINSIDE HEIGHT TO SE 6 FT.
OUTRIGGER TRENCHES COVERED OVERLEAVING 4-FT. CLEARANCE AT INSIDEOF EMPLACEMENT AND SLOPING TO
3-FT 3-IN. CLEARANCE AT OUTER END

Figure 58. Emplacement for height finder SCR 547.

(Camon-flage omitted.)
likely, the cable is wrapped in several thicknesses ofburlap or cloth to prevent damage when it is dug up
later. In mobile situations cables normally are notburied.
62. EMPLACEMENT FOR FIRE UNIT OF 40-MM
ANTIAIRCRAFT ARTILLERY. a. Gun and director. The emplacement for gun and director of a 40-mm
110

07-\

PERSPECTIVE

43

I-

PLAN

(D SCR-268.
Figure 59. Radar emplacements.

(Camouflage omitted.)
111

REMOVABLE
BREASTWORKTO CLOSEENTRANCE

4-FT CLEARANCE EACHENDTO PERMIT dACKS TO
BE EMPLACED.
4-FT CLEARANCE EACH SIDE TO PERMIT REMOVALOF COMPONENT BOXES.
INSIDE HEIGHT TO BE 8FT. 4iN.

® SCR-545.

REMOVABLE
BREASTWORKTO CLOSEENTRANGCE

I-FTCLEARANCE-FT. CLEARANGCE TO
OPEN SERVICE DOoR

4'FT.CLEARANCE EACH SIDE TO PERMITOPENING OF OPERATION DOORS.
INSIDE HEIGHT TO BE 10 FT 4IN.

() SCR-584
Pigure 59 -Continued.
112

antiaircraft artillery fire unit is laid out as indicated infigure 61. With the director pit so located, the director is 13 feet from the pintle center of the gun and thedead arc extends 70 ° to the rear from the side outrigger.
The dead arc extends 35 ° on either side of the gundirector line. The director pit is 6 feet in diameter. A// ! ,I I)

CLOTHWRAPPING

Io
id\~ FT.

2 FT.

I

CABLE

Figure 60. Trench for burying power-trailsmission cable.

(Camouflage omitted.)
short tunnel for the cable connects the director and gun
pits. The inside height of the emplacement is not over
3 feet 9 inches to permit horizontal fire. An elevation
stop is constructed to prevent the gun being depressed
below 400 mils in dead are. When the director is not
used, there is no dead arc. The ramp is closed off withsandbags or an earth parapet. It is constructed as aseparate unit to make removal easy. Four ammunition
niches usually are provided in the sides of the pit.
113

MUMT

POSITION

DIRECTORR
II
PiT
·

t.

OF
OF DIRECTOR
DIRECTOR

PLAN

DIRECTORGROUNDPITLINEHOU OF ESUMPLAC

WF

SUMPE

GROUND LINE
SECTION

Figure 61. Emplacement for 40imm antiaircraft gun and director.

114(Camouflage omitted.)b. Power plant M5 or M6 (fig. 62). The emplacement for an M5 or M6 power plant is a rectangular pit
with a trench for the operator at one end. At static
positions cables usually are buried (see par. 61 n). An

PLAN

EXHAUSTGROUND LINE PARAPET

*'

I

adsf

1

ABOUTOUTSECTION ON LINE "A-A"
Figure 62. Emplacement for power plant M5 or M6.
(Camouflage omitted.)

extension should be provided for the exhaust to carry
fumes out of the pit.
e. Machine guns. See paragraph 40.
115

63. ANTIAIRCRAFTSEARCHLIGHT SECTIONEMPLACEMENTS. a. Searchlight (fig. 63). The emplacement for the light is a circular pit 121/2 feet indiameter and 4 feet deep from the top of the parapet.

- SUMP

USEDt)RAINAGE TO
LOW GROUNDROTE:TO CONSTRUCT
ALL-AROUNO
9PARAPET.
/PLAN

REMOVABLE SANDBAG
BREASTWORI MAY BE
PL.ACED IN RAMP

PARAPETSECTION THRU RAMP
Figure 63. Searchlight emplacement. (Camouflage omitted.)lAt one end is a ramp. It is closed off with a sandbag
parapet after the light is in the pit. Protection is limited because of the necessity for illuminating planes at
low heights.
116

b. Control station (fig. 64). The emplacement forthe control station is a circular pit about 61/2 feet indiameter and 5 feet deep from the top of the parapet.
It provides protection for all parts except the binocu-

SPOIL USED TO
CONSTRUCTALLAROUND PARAPET

PLAN

*

PARAPETGROUNDLINESUMPSECTION

Figure 64. Emplacement for Searchlight control station.
(Caumoufnlage omitted.)lars; these must have an unobstructed view of lowflying airplanes.
c. Machine guns. See paragraph 40.
d. Power plant (fig. 65). The emplacement for the
searchlight power plant is a rectangular pit 13 feet117

long, 10 feet wide, and about 6 feet deep from the topof the parapet. It protects power plant and operator.
EXHAUST

9.

'_i .13.

REMOVABLE BREASTWORK IN RAMP

PARAPETGROUNDLINE

SECTION

Figure 65. Emplacement for searchlight power plant.
ouflage omitted.)(Cam-

An extension should be placed on the exhaust pipe tocarry fumes out of the pit. Searchlight cables should
be buried the same as other cables.
11864. CALIBER .50 ANTIAIRCRAFT M A C H I N E
GUNS. a. Multiple, caliber .50 machine-gun carriage
M51. The emplacement for the M51 multiple, caliber.50 machine-gun carriage is similar to that for the M7
generator trailer (fig. 55) except that it is less deep,
being about 4 to 41/2 feet in depth, measured from the
top of the parapet.
b. Caliber .50 machine gun, water-cooled, M2, on
M2A1 mount (fig. 66). The emplacement for the M2
caliber .50 machine gun, water-cooled, on an M2A1
mount is a circular pit 8 feet in diameter and slightly
less than 4 feet deep from the top of the parapet. Thereis an additional 3-foot excavation under the parapet on
one side for water chest and ammunition.
c. Caliber .50 machine gun, water-cooled, M2, on
M3 mount. The emplacement for the caliber .50 machine gun M2, water-cooled, on an M3 mount is thesame as that for the M2A1 mount described above
except that the depth is less, being about 3 feet fromthe top of the parapet, and the inside diameter isgreater, being about 9 feet.
65. MISCELLANEOUS. a. Command posts. Command posts are protected whenever practicable. Shelters of the type described in chapter 5 give excellent protection but require considerable time and material toconstruct. An improvised command post affording
protection from the weather and some protection fromblast, splinters, and small-arms fire is shown in figure
67. A rectangular pit about waist deep is excavated andthe spoil piled to form a parapet about 11/2 feet backfrom the edge of the pit. The bows from a truck areplaced over the pit, and the canvas top from the truckis placed over them to form a waterproof covering.
119

Similar shelter is given by a tent placed in a pit surrounded by a parapet.

A::·:.:::

BOXE~MVMUNTION

PLAN

PARAPETGROUNDLINE~~3'

LOGS SAND bAG' REVETMENTSECTION ON LINE"A-A'
Figure 66. Emplacement for caliber .50 machine gun, watercooled, M2, on M2A1 mount. (Camouflage omitted.)b. Kitchens. For protection, stoves may be placedin pits surrounded by parapets. However, when this isdone, care must be exercised to prevent fires or explosions from gasoline fumes.
120

AS

;

·

' ;

AG~~~~~~m

j~~j

ZI

<,~~~~~~~~1,eiEE~~~~~s~

121

WI

I

(

WI

122

c. Radios. Radios are protected in pits; each pit isjust large enough for radio and operator and deep
enough that only the antenna is exposed.
d. Vehicles. The motor and the tires of a vehicle
are the parts most vulnerable to fire effect. A large
pit with entrance ramp will give such parts protection
from blast, splinters, and small-arms fire. In hilly
country partial protection is obtained by digging a cut
in the side of a hill large enough to protect the front
end of a vehicle driven into it. The rear tires are protected by sandbagging.
e. Multiple-gun motor carriage M13, M15, or M16(fig. 68). Emplacements for multiple-gun motor carriages, which are mounted on standard half-tracks, consist of pits to fit the vehicles. Each pit must be of adepth to allow the weapons to fire horizontally, and its
bottom must be nearly level. Access to the pit is by asloped ramp. Usually the vehicle is backed into thepit to permit more rapid exit if the need arises.

123CHAPTER 5SHEL TERSSECTION I
GENERAL
66. SCOPE. This chapter covers various types ofshelters employed in combat operations. Included isa discussion of tactical and technical requirements ofshelters, methods of construction, and type designs.
Ammunition shelters are described in paragraph 52.
67. CLASSIFICATION. a. Based on degree of pro.
teetion. Protected shelters are classified according to
the degree of protection they afford.
(1) Blastproof and splinterproof shelters. These
shelters protect against rifle and machine-gun fire,
grenades, and light mortars; splinters of most highexplosive shells and bombs; and blasts of 100-poundbombs exploding not closer than 50 feet. They do notprotect against direct hits by bombs or artillery projectiles.
(2) Light shellproof shelters. Light shellproof
shelters protect against direct hits by 105-mm shells andfragmentation bombs.
124

(3) Shellproof shelters. Shellproof shelters protect against continuous bombardment of shells up to 8
inches and direct hits by bombs up to 200 pounds, aswell as against blasts of bombs up to 500 pounds exploding not nearer than 25 feet.
h. Based on method of construction. According
to the method of construction, which depends on thecharacter of the ground, materials available, and protection required, shelters may be further classified asfollows:(1) Surface. Surface shelters have maximum observation and exit facilities and require a minimum oflabor; on the other hand, they are relatively conspicuous,
require considerable cover material, and provide theleast protection of the shelters mentioned here. They
are seldom used for the protection of personnel in advanced positions unless they can be concealed in woods,
on steep reverse slopes, or among buildings; or unlessthe underground water level is so close to the surface
that the cut-and-cover type of shelter cannot be used.
Shelters consisting of almost any type of small, improvised shed, covered with a layer of earth, may be used
for the protection of ammunition and stores. These
shelters should be of small capacity, well dispersed, andcarefully concealed.
(2) Cut-and-cover. (a) This type, intermediate
between the surface and the cave shelter, is constructedin an open excavation which is backfilled around andover the structure to the level of the original surface,or somewhat above. The resisting power of the overhead cover is increased by layers of concrete, steel
beams, broken stones, or other materials with highresistance to penetration.
56397

44--9

125

(b) The cut-and-cover shelter is better adapted
than the cave shelter for use as a dressing station. It
is more quickly constructed, more easily cleaned, better
ventilated, and offers easier means of admission andevacuation of casualties. However, it usually requires
much larger quantities of materials to provide the same
protection, does not resist intensive shelling as well, andis harder to conceal.
(e) When the use of cave shelters is impracticalbecause of surface or underground water, hardness ofunderlying rock, or the rapidity of exit required, cutand-cover shelters sometimes may be used. They arealso suitable in wooded areas or in buildings, where concealment is easy and ample material is available, and insituations requiring immediate shelter.
(d) Unless they are constructed partially or whollyof concrete, cut-and-cover shelters do not offer muchprotection against shells heavier than the 6-inch type.
(3) Cave. (a) Cave shelters are constructed entirely below the surface by mining methods, and havea cover of undisturbed earth. They are the least conspicuous of all types, afford effective protection before
completion, and require the minimum material. Theirdisadvantages are: limited observation, congested living
conditions, small exits, difficult drainage and ventilation, and time required to build.
(b) It is difficult to increase overhead protection ofthese shelters after completion, since protection depends
upon depth at which the chamber is built. For thisreason, in determining the depth, it is important not
to underestimate the protection needed. On the other
hand, it is equally important not to overestimate it
because of the extra time, labor, and material involved.
12668. TACTICAL CONSIDERATIONS AND RE.
QUIREMENTS. a. Purpose. The primary purposeof a protected shelter is to permit troops or important
installations to remain in comparative safety at or near
their combat positions during hostile bombardment.
b. Terrain. Reverse slope positions, since they are
difficult for artillery to hit and usually are easily
drained, make excellent locations for shelters. Wooded
areas and buildings, which provide materials andfacilitate concealnment, are also desirable.
e. Location. It is of the utmost importance near thefront to have the shelters near where the troops who
occupy them are needed. This rule is relatively less important toward the rear. Facilities for cover and concealment also influence the location of shelters. Everyadvantage which the tactical situation permits should
be taken of natural shelter.
d. Ease of exit. (1) 'I'he occupants of a shelter
must be able to get out rapidly. This is particularly
important in shelters located near the front, where
troops must be able to get out and occupy their fighting
positions in the small time available between the enemy
bombardment and the infantry assault.
(2) Exit is made easier by designing shelters withsmall capacity, minimum depth below ground, and unrestricted entrances.
(3) Large shelters are provided with at least two
entrances, and preferably with a third for emergency
use. Small shelters are provided with exits as necessary. Extra exits should emerge at a different placefrom the main exit and where practicable at points
well concealed or camouflaged. Entrances should bespaced aL minimum of 40 feet apart to avoid the dangerof one shell or bomb burst blocking two entrances.
127

Large systems of cave shelters should provide one entrance for every 25 men.
e. Concealment. .It is important that the locationand number of shelters be concealed from enemy air
and ground observation. Changes in the appearanceof the terrain must be avoided. Materials and spoil
must be concealed or camouflaged as the shelters arebuilt. Strict camouflage discipline must be enforced
among working parties. Surface shelters may be hidden by terrain features such as woods or buildings.
Cut-and-cover shelters should be kept low.
f. Observation. If practicable, shelters should belocated to afford necessary observation, and should be
provided with means of observation, for example, loopholes in a surface shelter, or a camouflaged' periscopein the roof of a cut-and-cover shelter.
g. Application of types. Because of the time element and the construction difficulties in mobile warfare,the blastproof and splinterproof shelter is the typeusually used. The necessity for shelter becomes greater
as stabilization develops and details of the position
become known to the enemy. In the rear parts ofthe defended area, larger and deeper shelters are both
permissible and economical. These usually accommodate one or two squads or a platoon. They may be
developed from the emergency shelters initially constructed. Shellproof and cave shelters are used only instabilized situations.
h. Requirements for shelter in advanced posilions. (1) Shelters in the advanced lines should be(a) Well distributed, placing troops close to their
combat positions.
(b) Constructed without going to great depths, toprovide for ease of exit.
128

(c) Provided with direct and easy exits, even atsome sacrifice of cover.
(d) Of small capacity (from two to twelve men).
(e) Of a type that can be constructed rapidly.
(f) Concealed as thoroughly as possible.
(2) These requirements usually limit the type to theblastproof and splinterproof shelter.
i. Requirements for shelters in rear positions.
Shelters in rear positions may be larger and deeper thanthose at the front. Occupants usually have more timeto emerge after warning of attack. Also in these areas
shelters can be given maximum overhead cover to withstand bombardment of light bombs and heavy shells,
giving occupying troops the necessary rest and a feelingof security. If underground water conditions permit,
the shelters are built entirely below the ground. They
are carefully hidden from enemy aerial observation.
69. TECHNICAL CONSIDERATIONS AND . RE.
QUIREMENTS. These include·a. Subsurface conditions. Subsurface conditions
such as extent and character of underlying rock, position and thickness of impervious and water-bearing
strata, and amount of water to be controlled.
b. Facilities available. Facilities available, including time, personnel, tools, material, and transportation.
e. Drainage. Drainage of deep shelters sometimes
becomes a complex problem. It includes exclusion of
surface and rain water from the entrance, exclusion of
seepage from the interior, and removal of water thathas collected in the interior.
(1) Surface and rain water. Surface and rainwater must be excluded from all shelter entrances. Ifshelter is enforced from a trench and drainage is slug129

gish, two sumps may be dug in the bottom of the trench,
at least 6 feet from the sides of the entrance, andstrongly revetted. The bottom of the trench in front of
the entrance must then be graded to the sumps so thatthe highest point is in front of the entrance (fig. 97.)
At times it is possible to dig a sump in front of the entrance and grade the trench so that only a limited portion drains into it. Direct rainfall into entrances isprevented either by the design of the entrance or by theconstruction of some form of weatherproof shelter above
it. Baffle boards placed at the entrance floor are useful
to keep out surface water.
CORRUGATED SHEET METALROOF SHEETINGTOSTS
Figure. 69. Corrugated metal to waterproof shelter roof.
(2) Seepage. Protection against water seeping
into shelters is important. In a surface or cut-andcover shelter this is accomplished by placing tarpaper
between the sheeting and the cover. In cave shelters astrip of corrugated iron may be placed on the cap of theframe (fig. 69). Sheeting is then driven over the iron.
Space between caps is filled with an additional piece ofcorrugated iron supported by struts. Seepage is thus
carried to the sides of the chamber, where it collects in aditch leading to a sump.
130

(3) Removal of water from chambers and galleries. Galleries should be driven on a 1-percent (or 1foot to 100 feet) grade longitudinally, and all slopes
should fall toward a point or points where the water
can be disposed of. If the shelter has a level entrance,
regulate slopes so that water will run to the mouth. The
gallery floor should slope laterally in a 1-percent grade
and a ditch should be dug along one side. In a shelter
entered by incline or shaft, a sump must be formed at
the bottom from which water can be removed bypumping, siphoning, or bailing.
d. Ventilation. (1) Importance. Ventilation isa particularly important factor in cave shelters. It
includes the following problems:(a) Providing sufficient circulation of fresh air in
the incline, shafts, galleries, and chamber.
(b) Gasproofing, or exclusion of gas from all partsof the shelter.
(e) Providing pure air by means of air purifiers(collective protectors) when the entrances and ventilation shafts are closed during a prolonged gas attack.
(2) Circulation of fresh air. (a) In surface andcut-and-cover shelters sufficient fresh air usually is
obtained by keeping entrances open.
(b) In cave shelters ventilating shafts usually arenecessary in addition to entrances. They are small
vertical shafts, which iUmay be bored from within after
the completion of the shelter. A stovepipe through ashaft materially assists circulation of the air. In verylarge and elaborate systems of shelters a draft may becreated by fans.
(e) A gallery should not be driven more than 60 feetwithout artificial ventilation. A gallery with a single
opening is ventilated by forcing fresh air to the working
end through a duct of wood, metal, or canvas. A pres131

sure blower worked by hand or power is an essential
item of mining equipment. For excavations of moderate extent a portable forge forms an expedient ventilating device. Drill holes through the roofs of galleries
promote ventilation. In a system of galleries having
two or more outlets, air may be forced out from one
outlet and drawn in through another. Screens or doors
may be arranged to guide the distribution of fresh air.
Vacuum operation is never as satisfactory as a pressure
system.
(3) Unventilated shelters. Shelters not provided
with collective protectors should be used only by personnel who are to remain inactive during occupancy.
Since an inactive man requires about 1 cubic foot of air
per minute, the capacity of unventilated shelters islimited in part by the difficulty of providing unusuallylarge shelters. Initial air-space requirementsfor shelters for not over 12 men are 150 cubic feet per man.
'(See table III.)TABLE III.

Capacities of unventilated shelters
Outside °air below

90 F.

Capa-

Type of shelter(rSpae (cubic iet

per personm)

per person)l

__
Rest

Undergroundorabove-

ground walls of low heat [conductivity.2
7condlctivity

Aboveground walls of highbheat eonductivitv.'___
Normal
desk
Rest
work

Normal
desk
work

10
25
50

200
300
400

360
540
750

240
360
500

500
725
1,000

125

235

425

270

540

300

540

380

50
10

50

400
150

750
270

I Based on occupancy of 3 hours.
.IWlls of wood on dry earth have low heat conductivity.
i WValls of metal. concrete. masonry, and damn earth have hla

132

ooP.

Space (cubic actlf men)

Outside air above
]

500
180

hheat

1, 360000
720

onductivity.

e. Terrains.

Terrain should be considered withspecial reference to the effect of slope on the type ofentrance and the rapidity with which overhead covercan be gained, and to the disposal of spoil.
70. GASPROOFING. a. General. It should be possible to make all shelters gastight. A shelter not in
use should be sealed to exclude gas. Due to their low.
level, protected shelters are particularly subject to gas
concentrations, and protection must be provided by curtains in entrances. During extended gas attacks men
must be able to work and rest inside the shelter withgas masks off. This is of greatest importance in shelters where wounded are placed and, in shelters used fortelephone central and signal stations, observation posts,
headquarters, and other activities where the efficiencyof the occupants would be considerably reduced by wearing gas masks.
b. Entrances. The standard M1l gasproof curtainis used to keep out gas. If it is not available, adjustable curtains may be made of blankets on light, sloping
frames, built to fit snugly.the individual entrance.
Frames should be nailed securely to the sides and top of
the entrance timbers. For cave shelters it is sometimes
necessary to place gas curtains on the steps, but whenever possible they should be placed in horizontal entrances or horizontal approaches to inclines.
c. Other openings. Windows are covered with single curtains. Al crevices should be caulked with clay,
old clothes, or sandbags. Plugs, to be inserted during
gas attacks, should be provided for periscope drainage,
and ventilating openings. Flooring or steps in front ofgas curtains should be kept clear of mud and refuse.
Curtains should be kept moist with water or gasproof133

ing solutions. Fresh chloride of lime should be kept
on hand and, when the area is gassed, should be placed
between gas curtains at the entrance so that personnel
entering the dugout may neutralize mustard and otherpersistent gases on hands and feet.
d. Air locks. Air locks are intermediate chambers
between the outside and inside of shelters. They allow
passage into the shelters, while excluding gas. Figure
70 shows a standard air lock suitable for most types of
surface and cut-and-cover shelters; table IV shows thebill of materials for its construction. Where desirable,
construction may be modified to provide greater headroom. Figure 71 shows an air lock used in first-aid
shelters, designed to allow the passage of litters. It is
adaptable to the shelters described in this chapter by increasing their height and width. Table V shows thebill of materials for its construction.
Curtain doors at each end of the air lock usually are
constructed with standard M1 gasproof curtains. Whenan air lock's outer doorframe projects from the entrance,
the curtain must be about 4 inches wider and 4 inches
longer than the doorframe. If the air lock is built backinto the entrance the curtain must be the same width as
the doorframe. When not in use the curtain is rolled up
and placed on top of the air lock or in a box-shelf above
the top of the doorframe. (For details of the Ml gasproof curtain see TM 3-350.)
e. Collective protectors. (1) These devices are set
up outside shelters to purify incoming air by removing
chemical agents. Several types are designed to meet
specific needs. Most collective protectors are driven byelectric motors. Power is provided by a portable generator set, or taken from commercial sources when available. Connected directly with the motor is an air blower
134

STANDARD

I1

GAS-

Z

R

N Ip

E16FRAME

URTAiNO/UNNTARPAPER>I z/\

DIAGONAL
LINING\' SHEATHIN//rXFLOORIN\;SECTION ON LINE A-A-

~E,~

4

.

, ,,
BRAC

_,

,,I_

FLOOR*oo

TOP VIEW (C RTAINS REOVED)LE*6'tDIAGONAL~SHEATHINGI
1 TARPAPf_

DETAILEIM
TARPAPER STANDOAROD

LININGT AS1

N
ACURTAI
2'll~f----6~6·--rl--

SHORTEN BACKSTRIPS
2 AT EACHENDSECTION 'E-EI(GURTAINS REMOVEO)TRIPOFBLANKETDETAIL 0GC
I TAINSIDE ELEVATIONEND ELEVTIOK,

Figure 70. Standard air lock for shelter.

135

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CONTAINERFORGAS CURTAIN

ROOF

WHEN NOT

PANEL

rE

No.NE
CURTAIN
G6AS SIDEPANEL--//ON LINE A-A

TARPAPER UNDER FLOOR /SECTION

j

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Cas

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CUR.TxtONTAINER
R

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S
BLPS
°TTI\ESAt

TARIER LININ
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SIDE PIANL N°G2

DETAIL-C(SHOWING GAS CURTAIN)

DETAIL-D

Figure 71. Air look for first-aid shelter.

137

CURTAIN
ROOF PANEL

SIDE
pANELN t

SIDE PANEL NO.2

URTAI
FRAME

STANDARD
GS CRTAIN

Z'x8"
FLOORINGrSILL

SECTION ON LINE'E-E"
TARPAPER
LINING'L 3
Ij

FRONT ELEVATION

G-.--j2

r-I- T

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BOARDS

c-

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22-2

MEMT

3'-31

J
3iA
CLEATSSECTION ON LINE"F-F

ROOF
PANEL
TARPA

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DETAIL

//'

2"x8" IFLOORING

2TRIP OFBLANKET
-

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SILL

2
TARPAPER UNDER
FLOOR

a2-1'x6

PTARPAPER
LININGDETAILH

ISOMETRIC DETAIL OF J(GAS CURTAIN REMOVED)

Figure 71-Continued.
138

3

FBRACE

LININGSIDE
PANEL No.It

TOP VIEW OF ROOF PANEL_ 4 ".,--I.16'BOARDS~

INSIDE VIEW OF SIDE PANEL NO. I(SIDE PANEL No.2 SAME-REVERSED)SIDE
PANEL N

8"3'

4

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which draws outside air through a metal hose or pipe,
forces it through a canister for purification, and thence
into the shelter. Since concentration of gas invariably
is greater near ground level, the air intake should be as
high as practicable. The collective protector M1, which
is a typical type, has a capacity of 200 cubic feet of air
per minute under normal operating conditions.
(2) Collective protectors are obtained from the
Chemical Warfare Service, and are installed in shelters
intended to be used for a considerable time, such as
shelters for command posts, resting troops, and firstaid. Only shelters which have been made reasonably
airtight should be equipped with collective protectors.
f. Sanitary conveniences. Sanitary conveniences
should be provided in all but air-raid emergency sheltersand surface type shelters. Disposal is by chemical
closets, septic tanks, or drainage into special sewers.
71. OVERHEAD COVER. Figure 72 shows a typical
overhead cover for protection against penetration andexplosion of projectiles.
a. Bursting layer. The bursting layer covers theentire top of the shelter and extends beyond the top a
distance equal to the depth of the shelter floor below theground. The burster layer is made of standard bursters(fig. 73), standard reinforced concrete beams (fig. 74),
rubble masonry, or poured concrete. Table VI shows
required thickness of burster layers for different projectiles.
b. Distributing layers. The distributing layers
tend to distribute the effects of explosion. The lowest
distributing layer also bears the weight of the overhead140

cover and transmits it to the berms of natural soil. The
minimum length resting on the berm is equal to thethickness of the bottom cushion layer, plus 1 foot. Logs
wired together, steel I-beams, rails, or concrete beams set
on edge, are used in distributing layers.
e. Cushion layers. Cushion layers between bursting layers and distributing layers are made of sand,

L

E

CAMOUFLAGE LAYER

RM 'H-?~10 r.STiANDAD B"URSTEnBoSL'C*.*.CRUSHED
ROCK

I~ l

Ba'ocS~3'-~~~i~ln~d

TOGETHER
W;LOGIREDr
Z'
TAMPED~EARTH

TOP CUSHION LAYERDISTRIBUTING LAYERTAMPEO EARTH =,>E

BURSTER LAYERCUSHION LAYERDISTRIBUTING LAYER' NATURAL EARTH BERM
SUPPORTS PROTECTIVE
byCOVERING.
BOTTOM CUSHION LAYERCAPSHELTERL.'

NOTE:
OTHER SUITABLE MATERIALS MAY BE SUBSTITUTED AS EXPLAINED IN TEXT

Figure 72. Typical overhead cover for cut-and-cover shelter.
gravel, tamped earth, crushed rock, or brick rubble.
Preferably the top layer is of a granular material suchas gravel or crushed rock, and the other layers are oftamped earth.
5339P74 a

10

141

2

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SIDE VIEW
CONCRETE TO BE
2000 L/S IN (MINWEIGHT 145 LB.
1
19FTOF 6IN DIAROD
6 WIRE~~~~OR#

BURSTER ASSEMBLY
Figure 73. Standalrd burster block for burster layer.

142

___-

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--

-I--

* DEFORMEDCONCRETE TO BE

2000 Lssiso. I. (IKI

MADE IN LENGTHSOF 6,12 AND(5 FT
WEIGHT40 LOS PER FT,
FOR6'-o" BEAM-24 FT8' ¢ ROD ANDSFT 'I/4 ROD
FOR 2'-O' BEAM-48 FT/'O' ROO AND ifeT ¼IORODFOR I5-O'BEAM-60 FT %' RODAND22.FT 'V, ROD
CONCRETE BEAM

Figure 74. Reinforced concrete beam for burster or distributing
layers.

d. Example. The following is an example indicating the design of an overhead cover to provide protection against 105-mm projectiles (fig. 72). Materials
available are: standard concrete bursters, logs (8-inch
minimum diameter), crushed rock, and earth.
Assume a design as follows:
1 burster layer
2 distributing layers
3 intermediate layers(1) Total overhead cover required:
From table XXII, 30 inches concrete.
(2) Burster layer:
From table VI, 10 inches of standard burster
blocks are required, that is, two thicknesses.
Equivalent thickness from table VI is 8 inches
concrete.
(3) Balance of overhead cover:
Equivalent thickness is (1) minus (2) or 22
inches concrete.
143

TABLE

VI. Minimum thicknest of burster layer in inches
Projoctlle
Materlal105-mm

15 mm

100-pound
GP
bomb

5

..8

16

24

5
8

10
12

20
24

30
36

75-mm

Reinforced concrete slab (2,000
pounds per square inch minimnun)..
Standard reinforced concrete
burster blocks or beams ------Rubble masonry -----

5-(4) Distributing layers:
Use two layers of 8-inch logs, or total of 16 inches.
16
From table VII, equivalent thickness is 12, or 8
inches concrete.
(5) Cushion layers:
Total equivalent thickness is (3) minus (4) or
14 inches concrete.
Use three layers, top layer to be granular material, that is, crushed rock, and other two layers to be tamped earth.
Bottom cushion layer should be approximately
2 feet thick, or, from table VII, the equivalent
24
thickness is: 27, or 3Y2 inches concrete (approximate). This leaves the equivalent of 14
minus 3Y2, or 101/2 inches of concrete to be divided between the remaining two cushion
layers.
Middle cs/hion layer (tamped earth):
From table VI, 10.5 times 7 equals 36 + inchesor 3 feet (approximate).
144

Upper cushion layer (crushed rock):
From table VII, 10.5 times 3.5 equals 18 +inches, or 11/2 feet (approximate).
TABLE VII.

Relative thickness of materials required to provide
same overhead protection
Relativetbickness

Materialtiknes

Reinforced concreteRubble masonry -1.
Logs, 8-inch minimum diameter
Crushed stone or gravel -as..
Tamped earth ..-.............

72. STANDARD.-----------............
.-.

CONSTRUCTION.......

1
5
2
3. 5
7

MATERIALS.

a. General. Standard materials for construction ofprotected shelters are supplied by engineer agencies.
Their use results in economy of material and labor, butthey require transportation. In ordering these materials, if the size timber required is not available, a larger
size may be substituted.
b. Timbers. Round timbers cut near the site often
will be used in place of dimensioned lumber. Table
VIII gives sawed timbers and equivalent round timbers.

145

TABLE VIII.

Equivalent timbers used as beams

Saed timbers (width by depth)

EquivalentArea (square
inches)round timber(diameter ininches)Area (square
inches)I by4 --------------_--4
1% by 6 --.......------9
2by44
---8
2 by 6 ---------12
2 by 8_-- --------16
2 by 10 -. -------------20
3 by 39
3 by 6 ------------18
3 by 10-.
830
3 by 12 -8...36
4 by 4-----16
5 by 10 -....
50
6 by 6--.
36
8 by.-----64
8 by 12---------------96
8 by 14112
8 by 16 -----128
12 by 12--..
..........144

3
4%
4
5
6
7
3%
6
8
9
5
10
7
10
13
14
15
14

7.1
15. 9
12.6
19. 6
28. 3
38 5
9. 6
28. 3
50. 3
63. 6
19.6
78. 5
38 5
78.5
132. 7154. 0177. 0154. 0

NOTE. Theequivalentround timbers are also safe as columns. In making up thetable, primary consideration was given to resistance to bending.
oweveor, in every
case the round timber will resist more vertical shear than the timber of rooctangularcross section to which it is equivalent.

c. Corrugated steel arches. Arches are made fromheavy corrugated steel. Figures 75, 76, and 77 show details of standard types. The gauge of the corrugatedmetal sheets will vary with the type of overhead cover
to be supported.

146

BOANYMULTSIPLE

OF 2-0G
ELEVATIONCROSS SECTIONAPR XWEIGHTGE

ALTERNATIVEFOOTING
Figure 75. Corrugated metal arch for two-man shelter.

2'

PLACORRUGATED
'

1 I

'X

_

_

X

AW

METAL

LACROSSSECTION-ANY

OT

MULTIPLE OF 2STRIP

STD.5-O" PLATE_
PLATE
2 ST6

AGGER
2 6DETAILI D
IALLPLATES ARE INTER -T
CHANGEABLE SIZE FOR SIZ

III

OF

PLATE JOINT.;I.PER PLATE(POUNDS)LENGTH FULLI2
PPLATE PLATE
Zg6'
dB
5
'0
127127
" 6

7L

16

1047

ELEVATION
Figure 76. Semicircular corrugated metal arch for shelter.
147

d. Gallery and shaft eases. Cases are designed aslinings, without additional material except battens foruse in horizontal galleries, inclined passages, and shafts
driven under ground by mining methods. Cases also
APPROX.WEIGHT
PER. LIN.FT.(LBFNOTE.
6 STANDARD

FULL PLATESPER SECTION
PLATES

6lOBTAINABLE

226 B..
S

286 LB.a

IN MULTIPLES
7-6OF 2 FT.
LENGTHS UP
TO ANDINCLUDING
10 FT,SECTION A-A

,'

BOLT

4

PER
- TARPAtST4M P

DETAIL OF
PLATE JOINT(SEC--B)C
DETAIL OF MULTIPLATE JOINTi

SIDt ELEVATION

Figure 77. Circular corrugated metal arch for shelter.

may be used in constructing entrances to cut-and-covershelters. Note that frames in e below require sheetingin addition. Dimensions of lumber used in cases varywith the size of gallery or shaft (table IX). The
148

standard common gallery case, using dimensioned lumber and round timbers, and the improvised shaft caseusing round timbers, are shown in figures 78 and 79.
CApS3' I0'
3 s

°NG\

CAP G' DIA.LOG
40LONGSPREADER

RA8SETP.

POSTSTSPREAD'-lo
L
COMMON GALLERY
CASE

it

IMPROVISED GALLERY
CASE

Figure 78. Gallery cases for cave shelters.

.

p~aN1ISOMETR10

SIDE ELEVATIONCORNER DETAIL

Figure 79. Improvised shaft case for cave shelters.
e. Chamber, gallery, and shaft frames. (1)Standard frames are shown in figure 80. They are usedin horizontal or inclined passages, or in shafts, to support sheeting. In shafts, all timbers of a frame are thesame size as frame posts. The dimensions permit frame
149

spacing not over 4 feet on centers. Frames can be improvised from round timber.
(2) The chamber frame is used in rooms or chambers of cave shelters. The posts may be 6- by 6-inch
timber, or round straight logs at least 6 inches in diameter at the small end, and as free as possible from knots.
Caps are 6- by 10-inch timber.
CAP6x".

4|X0"

GAP60"

x'-9-O

4"SPREADERSPREADER

E

6"xe"

*

.Postst

r6e POSTS-e

SPFRADER|b~eSILrJ 5,4|

6'· SILLCOMMON GALLERYFRAMECHAMBER GALLERY
FRAtMEl

Figure 80. Standard frames for cave shelters.

f. Dimensions of standard galleries and shafts.
Tables IX, X, and XI give sizes of various classes ofgalleries and shafts driven by mining methods, and inelude bills of matelial.
TABLE IX.

Dimensions of standardtimbered galleries
Inside, clear

Size of gallery
HeightChamber -___.
Great __
Common.o-Half _-- ----Branch -.
Small branch -_....
150

6 feet 4 inches -..
-- 6 feet 4 inches-_
6 feet 4 inches ..-.
- 4 feet 6 inches ..-.
...... 2 feet 10 inches_-2 feet 4 inches -Width..8 feet 6 inches.
6 feet 6 inches.
3 feet 0 inches.
3 feet 0 inches.
3 feet 0 inches.
1--I foot 10 inches.

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g. Standard sheeting. Sheeting supports the earth
in chambers and galleries, and in inclines and shafts
where frames rather than cases are used. Two-inch
sheeting is furnished for the roof, and 11/2-inch or 2inch sheeting for the sides. Normally, it is in 5-footlengths where frame spacing is not over 4 feet on centers, and in 4-foot lengths where frame spacing is notover 3 feet on centers. It varies from 4 to 10 inches inwidth. Side sheeting is used for headboards and stairrisers, which are 11/2 by 10 inches by 3 feet 6 inches in
stepped inclines. Where ground conditions are favorable, round poles, 21/2 inches in diameter at the butt and
4 to 5 feet long, may be substituted.

NOTE,

CUI FROM 2%. 4
LUMIIER.

Figure 81. Wedge for driving sheeting.

h. Wedges are used in driving galleries and shafts
and also to brace timbers tightly against the walls androofs of the excavation, holding them in place during
settling. Dimensions of a common-type wedge areshown in figure 81. Other sizes may be used as needed.
i. Bunk posts. Bunk posts, 4 by 4 inches and 2 byby 4 inches, respectively, support the double tier ofbunks in shelters. The 4 by 4's should be placed under
the caps of the frames for additional support. Roundtimber, 4 inches in diameter at the small end. may besubstituted.
153

j. Use of lumber. Commercial lumber is used foritems such as props, bunks, gas curtain frames, battens
for holding timbers in place during construction, strapping together incline and shaft cases, and making bomb
recesses and baffle boards. Scrap lumber is used withwedges for blocking timbers in place.
k. Tools. Common tools include pick, shovel,
crowbar, pickmattock, sledge, hammer, saw, maul, ax,adz, tape, level, plumb line, pliers, and wire cutters.
Special tools, such as the air compressor or earth-moving equipment, may be of great help.

SECTION II
SURFACE SHELTERS
73. GENERAL. a. Surface shelters generally are
constructed of local materials, such as lumber from demolished houses or cut logs covered with earth. Corrugated metal also is employed. They are usuallybuilt for temporary use, or as expedients when theconstruction of more protective types is restricted byunfavorable conditions of ground soil or water. They
are of small capacity, well dispersed, and carefully
concealed.
b. Most surface shelters give protection only
against effects of blast, splinters, and gas. They are
unsuitable in areas subject to continual bombardment,
and are erected in advanced positions only when they
can be well concealed in woods or among existing buildings, or sited on steep reverse slopes. They are usually154

occupied by troops seeking shelter from enemy bombardment or gas attacks.
e. This type of shelter is especially suitable in mobile warfare when the details of a position are not known
to the enemy. As the enemy becomes acquainted withthe dispositions, shelters furnishing more protection
are required.
74. TYPES OF CONSTRUCTION; a. Wood shelters.
Wood shelters protect personnel against blast, splinters,
and gas attacks of short duration. They can be extended lengthwise to increase capacity. Baffle walls
divide shelters into compartments. Figure 82 showsdetails of one type of shelter that gives protection
against blast and splinters. The bill of materials for
it appears in table XII.
b. Metal shelters. Metal shelters are superior towood shelters because they are erected more rapidly,
require less outside cover, present smaller targets, andgive greater protection from weather; also, the shelter's
arch section gives greater resistance to blast, earth
shock, and movement. The disadvantages are the useof a critical material and the transportation of thematerial to the site. The most satisfactory type tobuild is circular, sunk one-third its height into theground, and covered with excavated material (fig. 83).
In this type the vertical surface exposed to blast is
reduced, and the earth movement resulting from anunderground explosion tends to lift the entire shelter,
exerting little destructive force. Figures 83 and 84
show corrugated metal shelters which afford protection
against blast and splinters. Tables XIII and XIVshow bills of materials for construction.
155

WIRE TIES-

1

216'6RLCEN

EARTH FILL
1. SCAO8S.

It

LLTu.SFLOORINStN FLOOR JOISTESLLCROSS SECTION t* C
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ELEvTATIONALTERNATV
CN

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TIES
:

2

STI

ALLN

'4IRE

EARTH FIL_CROSS SECTION SHOWINGARLTERNATIVE CONSTRUCTIO

Figure 82. Surface shelter constructed of wood and utilizing
earth blast wall.

156

TARPAPER ROOF COVERING
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WALLS AND ROOFOF SHELTER TO HAVE TWOTHICKNESSES OF Ii6'SHEATHING. FIRST LAYER TARPAPEROINGp."
TO BE APPLISD HORIZONTALLY ANO SECOND
2-2
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Figure 83: Surface shelter constructed of a circular section ofcorrugated metal and utilizing sandbag blast wall.

159

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Figure 84. Surface shelter constructed of semicircular sectionof corrugated metal and utilizing sandbag blast wall.

160
160

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SECTION III
CUT-AND-COVER SHELTERS
75. GENERAL. a. Cut-and-cover shelters are themost common type in combat zones. The shelter isconstructed in an open excavation, and spoil is backfilled around and over it to the ground level or somewhat above. It is built of local material, sized lumber
or timber, or corrugated metal. The protection afforded
depends on the type of construction and the overhead
cover. (See par. 71.)
b. This type of shelter is used to protect personnel,
supplies, and mnat6riel. It is especially suitable forcommand posts and first-aid or dressing stations, since
it is easily cleaned and ventilated and admittance andevacuation of casualties can be easily accomplished.
c. For drainage the floors of the shelter slope
slightly toward the entrance. Excavation should be
no greater than necessary to accommodate the shelter,and dirt should be packed tightly around the frame.
76. TYPES OF CONSTRUCTION.

a. Wood shel-ters. Wood shelters generally are built without floors.
Figure 85 and table XV describe a cut-and-cover shelterbuilt with dimensional lumber. Figure 86 and table
XVI describe the same type of shelter, using logs. This
type gives blastproof and splinterproof protection. The
thickness of overhead cover should not be increased
unless a heavier type construction is used. Figure 87
and table XVII describe a two-man shelter of wood,built with branch gallery cases.
163

END PANEL NO.G

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ON LlNE A-A,,SECTION

Figure 85. Out-and-cover shelter constructed of
dimensional lumber.

164
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Figure 85-Continued.

165
165

12 ,, ,2"

212

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I, SIDE PANEL NO I

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Figure 85-Continued.

166

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Figure 86. Cut-and-cover shelter constructed of logs.

168

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169

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FOR GREATER OVERHEAD PROTECTION A MORERESISTANT MATERIAL MAY BE SUBSTITUTEDFOR EARTH FILL.
LINE OFEXCAVATIONGROUND
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Figure 87. Two-man

ELEVATION

cut andcover

shelter

const.ucted ofbranch gallery cases.

171

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b. Metal shelters. Metal shelters are quickly andeasily constructed, are blastproof and splinter-proof,
and give the greatest protection against water and earth
shock. Flooring is necessary. Figures 88 and 89 andtables XIII and XVIII describe types of corrugatedE''

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565397- ---

173

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Figure 88-Continued.

174

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Figure 89. Cut-and-cover shelter constructed of circular corrugated metal arches.

175

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metal shelters. These provide blastproof and splinterproof protection. Figure 90 and table XIX describe a
two-man shelter of corrugated metal which may be
FOR GREATER OVERHEAD PROTECTION A MORERESISTANT MATERIAL MAY BE SUBSTITUTEDFOR EARTH FILL.
LINE OFEXCAVATIONGROUND
PARAPETTAMPED
EARTH
S ,
FILL

SANDBAGSSTANDARD
TRENCH

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2ISETIONSL2
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4FR

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INE IJ1FRONT ELEVA3
TION XCAVATION
VE?,AU
2'x8' GLL _BOTTOM LINE%

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5"0"
S-"-O Z

8" FLOORINGFRONT ELEVATION
Figure 90. Two man cut-and-cover shelter constructed of corrugated metal arches.

either cut-and-cover construction in loose soil, or cave

type in firm soil.
177

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c. Gallery frames or eases. By heavy construction,
similar to that required for cave shelters with standard
gallery frames or cases (par. 72), light-shellproof andeven shellproof cut-and-cover shelters can be constructed. Such shelters are, in effect, cave shelters constructed by cut-and-cover methods. Overhead cover isprovided as outlined in paragraph 71.

SECTION IV
CA VE SHELTERS
77. GENERAL. a. Cave shelters normally are built
in rear areas. They take longer to build than othertypes but, when time is available for construction, arepreferable to other shelters because they give maximum protection.
b. An accurate estimation of the necessary protection is essential for economical construction, since it
determines the depth of the chamber. A too-shallow
chamber site gives too little protection, or else requires
difficult and uneconomical later operations to deepen it.
A chamber set too deep wastes labor, time, and materials. Frequently in hilly terrain a tunnel dug into theside of a hill may serve as a cave shelter. thus eliminating the need for shafts and inclined entrances.
c. Most cave shelters are in earth. Construction inrock is mlusual except in certain types of permanent
fortifications.
d. Standard methods and materials simplify and
expedite construction. A consolidated bill of materials

179for a cave shelter built of standard parts may be madeup from the bill of materials in tables XX and XXI.

-.

5$3'-$"
6

53'-C¢-/T-E50-0o'650

4S INCLINE

45' INCLINE

24 OUNKS

24 BUN$SGALLERY TYPE

/

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AN C
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45 INLIE45'INCLINE

12BUNKS

12BUNKS

4IN NE

30 BUNKS

RECESS TYPE

Figure 91. Schematic lay-out of gallery and recess cave shelters showing entrances and inclines leading down to shelter.

These tables list the materials required to construct gallery or recess chambers, passages, grenade pits, inclines,
and air locks.

18078. TYPES.

Examples of cave shelters for various

purposes are:a. Infantry cave shelters (personnel). Figure 91
shows the standard arrangement of both recess and

SECTION ON LINE A-A

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ESE SHEETSECTION ON LINE'S--,

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Figure 92. Recess cave shelter.

gallery types; figure 92 and table XX, the recess typewith inclines; figure 93, the recess type with verticalshafts; and figure 94 and table XXI, the gallery type.
181

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VERTICALSHAdF

ASINCLINe

GRENADOPITSECTION 'A-AA

AMMUNITIONStLTELRSBELOWLEVELOFPERSONNELSHELTERsHLTERSVERTICALSHAFTABS
INCLINE
4O1NCLINESCHEMATIC PLAN

Figure 93. Schematic lay-out of recess cave shelter with vertical shafts.

182

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Figure 94. Gallery type cave shelter.

566397---13

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b. Command posts (fig. 95). Command posts layouts are not standardized. Note that in figure 95 passages are common-gallery size and rooms are chambergallery size, similar to those in figure 92. Command
45°INCLINECOMMANDSHELTERSFOR

POSTPLATOONk~ '30'-617-e

BoD 3O-ei,

COMMAND POST FOR A SMALL UNIT SUCH
AS AN INFANTRY PLATOONEN T R A N CE

p

45 INCLINE,_45'INCLINE

£

4-76-

~

COMMAND POST
FOR A COMPANY_

45-6&'COMMAND POST
FOR A BATTALION_-ENTRANCE.45'INCLINE

/
5'-3"

S6cS-Gr9-CjS-6 -6¶Y--

28 :9
9

COMMAND POST FOR A REGIMENT

Figure 95, Typical lay-out of cave shelters used for command
posts, showing entrances and inclines.
191

posts for larger units generally consist of long, recessed chambers along the passage to accommodate enlisted men's bunks, and small chambers at right angles
2"ROOF SHEETING

6Ei"CAPS

6i6"POSTSSECTION ON LINE A'A

GRAND GALLERY CASESWITH CAPS AND SILLS

93.-4'CUT TO 5'-G"

ALL SIDE SHEErING I

OUT LITTERSINLITTERS

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6'6"POST

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Figure 96. Cave shelter for aid station.

to the passage, normally used as combined offices andquarters for commissioned personnel. The maximum
length of these rooms without ventilating holes or shafts
is 15 feet. In computing floor space of command post
shelters, the area of passages is not included.
e. First-aid shelters. Figure 96 shows passages,
aisles, and inclines adapted for the movement of litters.
The rooms are made with standard chamber-gallery
frames, and the connecting aisles with great-gallery
192

frames having caps and sills shortened to 512 feet. The
usual 450 incline is too steep for handling litters andshould be reduced to 310 for this type of shelter.
Cave shelters are classified
79. CLASSIFICATION.
as the recess type and gallery type (fig. 91).
a. The recess type is 8/2 feet wall-to-wall, and employs the chamber gallery. The passage is at one side,with bunks perpendicular to the passage. The shelter
is economical in spade, labor, and material, requirements
being 75 cubic feet of excavation and 113 board feet oflumber per occupant. It is used wherever conditions
permit.
b. The gallery typeis 61/2 feet wall-to-wall, and employs the great gallery. The connecting passage orentrance is along the main axis of the chamber, withbunks on both sides paralleling the passage. Simpler
to cbnstruct than the recess type, this advantage is cancelled by its larger excavation and material requirements- 9 3 cubic feet of excavation and 185 board feet oflumber per occupant.
80. REQUIREMENTS. The factors to be considered
are: approach to entrances; entrances, which may be
inclined or not, as conditions require; room or chamber
proper; and connecting passages.
The pick, shovel,a. Tools.
81. EXCAVATION.
crowbar and pick mattock are the primary tools inearth excavation. In advancing an incline or gallery
only enough ground is opened up to accommodate thetimbering.
b. Removal of excavated material. In small headings spoil is shoveled into bags, which are carried to theplace of disposal. In fairly large headings, wheel193

b)arrows and small tramoars may be used. The removalof spoil through shafts is ordinarily by buckets andhand-operated windlasses or small power hoists.
e. Concealment. When the shelter is close to theenemy, spoil is deposited temporarily in those dumps
which can be used by day unobserved by the enemy. At
night men place the spoil in shell holes, old mine craters,
abandoned trenches, sunken roads, behind hedges, or any
other places concealed from the enemy in daylight. It
is bad practice to build mounds of spoil. All materialmust be carefully concealed, or camouflaged against
airplane observation, since fresh spoil of whatever color
is easily identified on enemy aerial photographs. The
path to the place of disposal must be concealed, toprevent the tracks showing on aerial photographs.
82. ENTRANCES (fig. 97). There should be at least
1 foot of initial headcover over the top of the firstcase of the entrance proper; and a burster course of 5
to 12 inches of rock, broken stone, or concrete slabs isplaced above the entrance not more than 1 foot fromthe surface. No attempt should be made to strengthen
the head of the incline by logs, rails, I-beams, concrete
arches, extra heavy timbers, or complicated bracing. Ifhit, such material is likely to cause a serious block because of the difficulty of clearing away debris in theentrance. The only protection against grenades being
thrown in the entrance is a lined pit 6 feet deep at bottomof the inclined shaft (see fig. 98). This is constructed
after the shelter is completed, and also acts as a sump.
It must be kept clear of debris. Grenade pits are
installed only where ground raids are likely to occur.
The best protection for entrances is concealment fromground observation and from aerial photography.
194/. PARAPE

BURSTER LAYERSNOT SHOWN.

GROUND LINE
TRENCHSi/

BOARDS'

STANDARD m I

TH
SIUMPES. DRANAGE

ITjxI%-6
3

CURTAIN

H

UCOMMONGALLERYRDS

SLOPE
BOTTOM OF TRETTENCHTHLEASTSIDES60SESAT
CENT~nNOT!:
OF ENTRANCESLOPE BOTTOM OF TRENCH
I"lO~x4-6"
AWAYFROM ENTRANCE ON
BAFFLE BOARD:OTH SIDES. DRAINAGESUMPS-OTH SIDES AT LEAST 6*-O'
FROM t OF ENTRANCE.

RISER SS~..,

Figure 97. Approach and entrance to incline to cave shelter.

(See FM 5-20.) To avoid ground observation, entrances are located on places such as reverse slopes andalong sunken roads. To avoid detection by aerial
photograph, they are located in trenches used for otherpurposes, or along other traveled routes. Locating
shelters in woods protects them from both ground andair observation.
83. APPROACH. a. Definition. The approach isthat portion of ground in front of the entrance tounderground works which must be excavated to provide
necessary headroom without sacrificing overhead cover.
195

The approach usually is necessary, whether the entrance
is from a trench (fig. 97) or from a reverse slope.
b. Approach from reverse slope. Except in cases
where the entrance is from an existing trench, or wherea reverse slope entry is made in a nearly vertical face,
an approach is necessary to reach the first timberedsection. .Usually, it consists of a narrow trench driven
forward into the slope on a slight upgrade to facilitatedrainage, until a vertical face is obtained high enoughfor installation of the first gallery case. Revetment
usually is needed near the entrance and, being con-spicuous on an aerial photograph, the approach must
be carefully camouflaged both during construction andafter completion.
84. DRIVING AN INCLINE WITH CASES. a. Nor.
mal construction. (1) To standardize construction, asingle type of incline, using standard gallery cases
placed vertically, is employed (fig. 9S). This type,also known as the stepped incline, may be built by unskilled labor. The normal size of case is the common
gallery type.
In driving an incline with cases (fig. 98) the dimensionsof a common gallery case are marked on the groundat the site of the entrance. Standard common gallery
cases are used except at the top of inclines of standard
trenches, where the posts of the first case are sawed to
5 feet 8 inches instead of 6 feet 6 inches, giving 4 feet
9 inches of headroom. This reduction in the size of thefirst case is necessary to maintain adequate overhead
cover above the entrance to the incline.
(2) Excavation for the sill of each successive caseis lowered 10 inches, providing for steps. Cases areused as described above, except that headboards and
196

LIE

A Q8AOSISFORFIRSTREN
HEAD'FSADRM

A TT N SCOMMON
E

TAN

GROS
ND
W
GAL~dGLLERY

5$RTINE SEL

Ae

-SECTION ON
GRENADE-IT MAE
TENO
AT',6
32
MISN
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NO 4$'iNGLINE
F

OVER
TS
3CASES

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I

GUASCURTAF
LINE
TCWR

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pARAPET

SAN ,'E,~5

DFEOR6T

xi-POSG FORN£URTAOECTI N ON LINE
FROM

.L. .FAVATCNO
AMF(SNOFENTRANCE)

Figure 98. Inclire for cave shelter.

risers are nailed in position to prevent earth from caving between successive caps and sills. The timbering
follows the excavation closely, to prevent "runs" inface or sides.
197

(3) In loose, caving soil, the cap must be put inposition first and supported while grooves for the
ground sill and posts are excavated. Two "crutches"(fig. 99) are used for supports. A crutch is an upright
EADBOHARD
CAAP
BLOC'IU

1I6"BATT EN
CRUTCHlII

t~x4P~oPt

II,

STANDA"RDSECTION,l

I I

SHOWINGi.
USE IN)-.
SETEPPED INCLINEPPERSPECTIVE VIEWI SHOWING USE IN PASSAGE)

OBLCK

-1 9

CHAIN

NOTE
6)
STEPPED INCLINE

59f

LfCKANDSHRTENPOST :aSTANoARD
WEDGES

REAR

SIDE

VIEW

VIEW

H-

O
O EYE-SCREW
TYPE
44'POSTDETAIL AT TOP

Figure 99. Use of "crutches" in driving gallery with cases.

198

piece of timber carrying a crosspiece equal in length
to the width of two cases. The upright piece rests
upon the ground sill of a case already placed, and israised to proper height by wedges. The part of thecrosspiece which projects forward is made 2 inches
higher than the rear part, to support the cap somewhat
above its final level and to allow posts to be easily inserted (fig. 99). The rear part is attached to the upfight piece by an iron rod or short chain. When thecase is set and adjusted to position, crutches are taken
down by removing the wedges, and are placed under the
next cap.
(4) Immediately upon being set, each case is tied
to the top and bottom of the previous one by shortlengths of sheeting. These are later replaced by 1by 6-inch battens (see app. I). The number of cases
required for a 450 incline for any depth equals the vertical depth between levels in inches divided by 10
minus 1.
b. First-aid shelter construction. The constructionof inclines for first-aid shelters is similar to normal
construction, except that a case of larger size than thecommon-gallery type is ordinarily used. While a 45°
slope is usually used for most inclines, a lesser slope ispreferred for first-aid shelters. A 310 slope is frequently used, in which event the number of cases equals
twice the difference in feet in elevation between levels
minus 1. This is based on a stairway with 6-inch risersand 10-inch treads.
85. SINKING A SHAFT. a. With cases. Shafts
usually are sunk with cases. A shaft case of required
size is constructed and placed on the site of the shaft,dimensions of which are marked on the ground outside
199

the case. The case is removed, and a hole is dug to thedepth of the case, which is placed in the excavation
with its top flush with the ground. Its position is carefully verified, and it is secured in position by packing
earth around it. Excavation is continued for the depthof another case, which is put in place as follows: one
endpiece is placed in position; the sides are engaged
with the end and pushed back into position; a pocketshaped excavation is made beyond the end of one of thesidepieces and running back 3 or 4 inches into the side
wall; the remaining endpiece is inserted in this cavity
far enough to allow its opposite end to slip over theside and fall into place by drawing against the sidepieces. The case may be toenailed and fastened to thehigher one by short battens. The next case is placedin the same way, care being taken not to excavate twoconsecutive pockets in the same corner. Pockets arefilled by stuffing earth from below before placing thenext case. Upon reaching the level of the top of thegallery, pieces on the gallery side of the shaft are omitted if the ground is firm; but, if it needs support, thesepieces are put in place and secured by cleats or braces.
b. With frames and sheeting. In sinking a shaft
with frames and sheeting (fig. 100), the size and position of the shaft are fixed first, then the top frame islaid down and staked in place, with guide marks on
the endpieces made accurately in the desired position.
The excavated area is made enough larger than the top
frame to take the sheeting all around. Usually theinterval between the first and second frame can be dug
without driving sheeting. It should be so undercut
that, at the level of the second'frame, it will be larger
in each direction than at the top by twice the thicknessof the sheeting. Gauge rods, cut to the length and200

width of the excavation and plainly marked at middle
points, should be provided for ease in measuring. The
inconvenience of working under the top frame may be
avoided by marking the sides of the hole carefully anddigging the first inerval before setting the top frame.

A

Ct

A

4 BATTENSGALLER¥CASESSUIPE DERIrTSYHEETIGPLAN

AT TOPHALVEDISOMETRIC OF
FRAME JOINT£30t-6'P:_
G;GO5TSl.

1 ESHEETING

PLAN AT BOTTOMF

BOTTOMFRAME

SECTION ON LINE "Ah-l

Figure 100. Sinking a shaft with frames and sheeting.

When the shaft is deep enough, the second frame is put
in place and nailedtogether. The top and second frame
are connected by nailing to them four battens of proper
length, two on each side (fig. 100), which suspend thesecond frame from the top frame at the proper interval.
201

The second frame is placed vertically below the top
frame, using a plumb line.
Sheeting is inserted outside the top frame, beveled end
first, bevel inside, and pushed down until its top is flushwith the top frame. The lower end of the sheeting iswedged out from the lower frame to permit insertionof second interval sheeting, and excavation of the second
interval is commenced. in ordinary soil, the sides ofthe shaft require support. The sheeting is therefore
introduced as the excavation proceeds, wedges previously placed being driven down as the sheeting isinserted. If earth pressure becomes great enough tospring the sheeting planks inward, an auxiliary frame
is added. This frame is similar to shaft frames, but
4 to 6 inches larger in outside dimensions. Sheeting
rests directly against the outside of this frame, and thus
is held far enough out to allow the third frame to beplaced and wedges to be inserted as before. The auxiliary frame then is removed and used in the next interval.
Successive frames are placed in like manner (fig. 100)
until the one directly over the gallery is reached. This
frame is placed at exactly the right height and the shaft
continued to the required depth. A frame is placed at
the bottom, its top level with the gallery floor, and the
sheeting is allowed to rest directly against the outsideof this frame. When the soil permits the sheeting isomitted, wholly or in part, over the portion of the shaft
which is to form the gallery entrance.
c. Precautions. In sinking shafts, special caremust be taken to make the excavation no larger thanrequired for placing the lining. If space is left outside the lining, the earth may give throughout the entire
height of the shaft, fall against the lining, and crush
it in.
202

86. DRIVING A GALLERY. a. With cases. The
operation is the same as for driving an incline withcases, except that the excavation is not stepped andheadboards and risers are omitted.
b. With frames and sheeting. (1) Two gauge rods
are prepared, giving the extreme height and width ofthe excavation, that is, the height of the frame plus two
thicknesses of top sheeting, and the width of the frame
plus four thicknesses of side sheeting. The middle ofeach gauge rod is marked plainly. A gallery frame is

4SHEE

TING EING

Figure 101. Driving sheeting with beveled cap and cap withstrips nailed to it.

set up, carefully located, and fastened in position withbattens and braces. The top gallery sheeting is started
on top of the cap and driven until held in place by theearth. It is given the upward pitch necessary to makeroom for placing the next frame and sheeting by abeveled cap, or by strips fastened on top and on therear face of a cap (fig. 101). The side sheeting is started
in the same way against the outer faces of the posts,
and is given an outward slant by bracing the outer ends
slightly away from the sides of the gallery. Earth isexcavated and the sheeting advanced, keeping the front203

ends in solid earth to hold them steady and to giveprotection to workmen.
(2) When the gallery is advanced one interval,
usually about 3 or 4 feet, a second frame is placed. Its
position is verified by the guide marks; its direction bya line; its grade by a spirit, mason's, or field level; andits plumb by a plumb line. It is secured in place bynailing battens to it and to the preceding frame.
2"ROOF

6xs #SHEETI NGCAPS=ST__

Figure 102. Using wedges in driving sheeting.

Wedges are inserted between the second frame and the
sheeting, to allow room for insertion of the sheetingfor the next interval, and the gallery is continued by thesame method (figs. 102, 103.) When the sheeting canbe advanced only by hard driving, the frames are inclined slightly to the rear and afterwards driven
forward until vertical.
(3) If, while advancing the sheeting, the pressure
becomes so great as to spring it, a false frame must be204used (figs. 104 and 105). This consists of a cap, a sill,
and two posts connected by mortises and tenons. Posts
have tenons and cap and sill have mortises at each end.
The cap may be rounded on top and, for facility in setrROor SHEETINGWEOGESSECTION ON LINE

I

A

A-A'

SIDE SHEETINGWEDGESCOMMON GALLERY FRAMES

PLAN

Figure 103. Wall andll roof sheeting showing wedges.

ting up and removing, its mortises are longer than thewidth of the tenons. The latter are held in place by
key wedges when the frame is in position (fig. 105).
The false frame is usually made the same height as thecommon frames, and wider by twice the thickness of563(39,7-

Z4

205

the sheeting.

In using this frame, the sill is placed ac-

curately in position a half-interval in advance, posts
are set up, and the cap placed upon them and wedged.
e"ROOF SHEETING

3'BRIGE

6'AP EOUNDEDTOP EDGE ROUNDED'~GALLERyF P MESFRSECTION ON LINE"A A-A'

SIDE SHEETINGCOMMONGALLEYRI

36 '8PIDGE

4WPOSTOUTSIDE EDGE

BATTENSFLSE FRAME

Figure 104. Details of constlruetion using false framte.

The whole frame is then raised about 2 inches by driving wedges under the sill, and is secured by battens (fig.
105.) The sheeting now rests directly upon the cap andposts, and has enough slant to clear the next frame by its
own thickness. The next frame is set up, wedges driven
under the sheeting. and the false frame is removed
206

(4) In loose, caving ground, when pressure on the
sheeting is too great for driving, it is relieved by the use
2#ROOF
2'

2

TEMPORARY
E4
BATTENSFALSE FRAMeSTANOARD
WEDGES?-- -PERSPECTIVE VIEW(SHOWING FALSE FRAME IN PLACE)

At

1 6-6

44'*4' POS

Y-;t4-

iCAP~-4.6'I
I

WEDGES

.4ain

4"x4"
POST

:(I: W~
4.
SEC.'A-A'

REY

WEDGE.
'

105.E

Figur

AJ

TENON tos
MORTISE6;"2

4%h SILL

SILL
F

-

OF MORTISE

DETAILa TENON JOINTELEVATIONNOTE:OUTSIDE EOGES OF CAPANO POST TO BE ROUNDED

Figure 105. Perspective view and detail of false frame.

of bridges (fig. 106). These consist of 3-inch blocks
equal in width and length to the cap or post. The
frame being in position, a bridge is placed over the cap,
supported at each end by wedges having the thickness of207

the sheeting.

The bridge keeps the rear sheeting frombearing hard on the cap, thereby allowing an opening
through which the forward sheeting is driven (fig. 106).
As the sheeting is driven forward piece by piece, it issometimes necessary to pick material away from thepoint of each board. In this manner the sheeting is ad-

&IDGE

/
2- ROOFSHEETfNG

SHIM'i~v- 6's

6'

SPREADER
STANDARDWEDGE

TEMPORARYBATTEN

Figure 106. Isometric view showing use of bridge.

vanced to its final position. The next frame is blocked
into position, and the same process repeated. Whennecessary to hold up the sheeting while placing the next
frame, a false frame, as described above, or posts andheadboard, may be put in place, to be removed when thenext permanent frame is placed. Side sheeting isdriven as for roof sheeting under similar ground conditions.
(5) To drive the gallery in very loose soil, a shield(fig. 107) may be used to prevent earth in front andabove from caving into the gallery. When the excava208

tion at the top of the gallery has advanced as far as
possible without causing caving to extend beyond the
top sheeting, a piece of plank a foot wide and equal inlength to the width of the gallery is placed directly
under the top sheeting against the face of the excavation(fig. 107), and held in place at its ends by braces secured~2E

E-,lO~x36.106
STRUTS

3"x6-W-0" JROOFBRIDGESHEETtNG,FALSEFRAME

COMMONGALLERY FRAN'.'1fOx4-O'
SHIELDBOARDSELD BATTENS

4'B
RI

0

SDTG

2'E4' GRACEi' 6 ' BELOBATTENGROUNTEMPORARY

'-0

L

BAEs

PERSPECTIVE VIEW(SHOWING SHIELD iAN
CEJ
I-~SIDE SHEETINGGALLERYFRAME

TEMPORARy BATTENHIELD BOARDS

S

PLAN

Figure 107. Use of shield in driving sheeting in loose, caving
soil.
209

to the gallery lining. Earth is removed until a second
plank of the shield can be placed, in the same way, under the first one. This is continued until the entire
face is covered. The top and side sheeting is driven
forward, the top plank of the shield is removed, earth
is excavated, and the plank placed ahead, after which
each plank in turn is removed and placed ahead.
87. CHANGE OF SLOPE. To pass from a horizontal
to an ascending gallery (fig. 108) the top sheeting isgiven the proper angle by holding down its back end
with a piece of scantling placed across the gallery, andthe side sheeting is given the proper inclination.
Trenches are cut in the bottom of the gallery for the
lower pieces, if necessary. In passing from a horizontal
to a descending gallery (fig. 117), the roof may be carried forward horizontally and the floor given the desired
pitch by increasing the height of successive frames until
enough headroom is obtained to allow inserting the
top sheeting for the descending gallery at the proper
height and in the new direction. The frame at thispoint is made with a cap upon which sheeting rests
directly, and a second crosspiece below it, serving as acap for the descending gallery. From this point forward, frames may be set at right angles to the axis of
the gallery. If the descending gallery is very steep,and the horizontal pressure of the soil is great, it may
be necessary to strengthen the posts of the last two or
three vertical frames by crosspieces near their upperends.
88. CHANGING DIRECTION HORIZONTALLY. a.
In changing direction horizontally with frames andsheeting, if the soil will stand unsupported for a dis210

tance of one frame interval, it is only necessary to place
one or more frames at an angle until the desired changeof direction is gained. Sheeting on the outside is
WEDGESROOFSHEEETINGSECTION THRU DSCENDING GALLERY'EDGES

rlO"$TRUTS

g galleriesTING

SECTION THRU DESCENDING GALLERY

Figure 108. Details of construction of ascending and decending galleries,

placed by running the forward end past the frame andthen inserting the rear end behind the last section of
sheeting (fig. 109). A short section of gallery may
211be put in to reduce the amount of work (fig. 109).
Frames with extra long caps and sills are required, andthe last one used is given an extia post on the inside
to take sheeting in the new direction.
I. SHEETI
NG_616" POSTS(D Outside wall, normal method.
i2

SHEETING
WEDGE

POSTS

I SHEETIN/O Alternatirve method.
Figure 109. Details of changing horizontal direction of gallery.

b. For abrupt changes of direction of large galleries, dig in the original direction past the turning
point and then start the branch gallery in the new212direction.

(See fig. 110.) The interval between theframes of the gallery of departure at the place of departure must be great enough to admit between them aframe and the side sheeting of the branch.
e. If the branch is oblique to the main gallery, its
width measured along the gallery of departure may be
eRECTANGULAR

BRANCH

j'----==l ,,"=?
F :_ - GALLERY OF
...
_-_-

.- L, _.--- :DEPARTURE\a',,<OBLIQUE BRANCH-- ------

2-.

GALLERY OF
DEPARTURE

i rOBLUE BRANCHFROM RECTANGULAR

Figure 110. Breaking out branches.

greater than that normally between the frames of thegallery of departure. In this case a short rectangularbranch is first broken out from the side of the gallery ofdeparture and the new gallery is broken out from theside of this short branch. The first frame of an obliquebranch should be so set that sides of the posts are parallel
to side walls of the branch, thus giving good bearing
to the side sheeting.
213

d. The floor of a branch is started at the level of thefloor of the gallery of departure. In soil which will
stand for a short time without support, the first frame
may be set up entirely outside the gallery of departureand may be the same height in the clear as this gallery.
However, when side sheeting is required in the gallery
of departure, the first frame of the branch must be set
up against this sheeting in the interval between posts.
This makes the clear height of the branch at this frame
less than that of the gallery of departure by a little
more than the thickness of the sheeting. When thefirst frame of the branch is set against the sheeting of
the gallery of departure, the sheeting may be pulled
or cut away to permit excavation, in either case beginning with the top plank.
89. CHAMBERS. In excavating a wide chamber,care must be taken to prevent earth from falling fromthe roof. Excavation of the entire width of thechamber at the same time should not be attempted.
Until the roof sheeting can be placed, the roof is supported by an earth column left standing in the chamber,and excavation for the side sheeting and next frame ismade around this column. The earth column is gradually removed as the roof sheeting is placed.
90. LINES AND GRADES. a; Line. In timber construction, a string stretched along shallow saw cuts inthe centers of caps and sills is the simplest method of
maintaining straight lines. Plumb bobs hung fromnails in the center of caps are used for lining by eye.
Sills are leveled and posts plumbed, while the frame orcase is being lined and blocked into place.
b. Grades. The minimum grade that will insuredrainage in galleries and chambers is about 1 foot per214

100 feet (1 percent). Uniform grades are difficult tomaintain without a level and a grade board. A convenient size of grade board is made from a straight-edge
piece of 11/2-by-6-inch lumber, 6 to 12 feet long, with asmall cleat nailed on one end. The cleat is of such
thickness that, when the board is placed on a surface
with a carpenter's level on top, the desired grade is
obtained when the level bubble is centered.
91. PLANS AND LAY-OUT. a. Plans. Before starting work, location sketches showing over-all dimensions are necessary so the proper material may beordered or prepared.
TWork is simplified if the shelter isb. Lay-out.
placed so that all entrances are perpendicular to thecenter line of the chamber. The chamber is built sothat its longest dimension is perpendicular to the probable direction of enemy fire. Lay a base line parallelto the long axis of the chamber, and mark this line sothat it can be relaid easily, should it be destroyed. Markthe center lines of the entrances on the base line, andfrom each side of the mark, at a distance equal to onehalf the outside width of the entrance, erect perpendicular lines to points where the first frames are to be placed.
Perpendiculars to the ends of a frame must be of equal
length, so that the first frames will be set parallel tothe base line. It,is important that these first frames be
set accurately. The horizontal distance of each framefrom the base line and the difference in elevation between
the various frames must be determined, usually witha carpenter's level and square. The axis of incline
must be carried in a plane perpendicular to the baseline, usually by sighting along the sides of the incline.
21592. RATE OF WORK. For calculating the size ofworking parties and the rate of work (including timbering, but exclusive of disposal of spoil on the surface),
the following figures may be accepted as average:a. Inclines. Common gallery, size 6 feet 4 inches by
3 feet, inside clear dimensions. One relief includes:
one man picking and timbering; one man filling sandbags and timbering; and one man carrying for each 10feet from working face to entrance. Average progressfor each 8-hour shift, about 3 feet 6 inches.
b. Passages. Galleries, commron gallery size: working party the same as for inclines; average progressfor each 8-hour shift, about 4 feet.
c. Chambers. (1) Chanmber gallery size, 6 feet 4
inches by 8 feet 6 inches, inside clear dimensions: twomen picking; four men filling sandbags and timbering,
who relieve pickmen as they tire; add two men for each
10 feet of carry; average progress for each 8-hour shift,
about 3 feet.
(2) Great gallery size, 6 feet 4 inches by 6 feet 6
inches, inside clear dimensions: working party same
as for chamber gallery; average progress for each 8hour shift, about 3 feet 6 inches.
d. Surface carrying party. One man can carry
100 sandbags for 200 feet in 8 hours under ordinary
trench conditions. One bag equals 0.5 cubic foot orabout 50 pounds.

216

APPENDIX IGLOSSARY OF TERMS
The terms used in this manual are defined as follows:
Air lock. An intermediate chamber, with a gasproof
curtain at each end, located between the outside and inside of a shelter (fig. 70).
Angle of repose. The steepest slope at which a heapof material, such as earth, will stand without sliding.
Batten. A strip of wood used for nailing across twoother pieces to hold them together, for covering a crack,or for holding tarpaper against wood.
Bay. The straight section of a trench between two
bends.
Brush revet'ment. Cut brush held against a wall by
pickets (fig. 14).
Brushwood hurdle. A woven rectangle of brushwood used as a revetment (fig. 13).
Burster blocks. Prefabricated, reinforced concrete
blocks so designed that a number can be wired together
to form a burster course (fig. 73).
Chamber. An enlarged room in a shelter, used as abunkroom or for other purposes.
Choked end. The end of a filled sandbag that has
been tied with twine.
Crutch. An upright piece of timber with a crosspiece at the top, used while driving a gallery as support for the caps until the posts for that purpose canbe inserted (fig. 99).
Dannert barbed-wire concertina. Prefabricatedwire-roll obstacle made of high-strength-steel barbed
wire.
217

Drainage lines. Channels or low lines of the terrain
in which water flows either continuously or intermittently.
Flume. An open wooden channel conveying water.
Gauge rod. A stick, cut to a definite length andmarked at certain intervals, used for checking the sizeof the excavation while driving galleries.
Gallerycases. Prefabricated framework used to line
galleries.
Gallery frames. Framework which holds in place
sheeting used to line galleries.
Grenade pit. A pit, usually at the end of an incline,
to catch hand grenades and limit the effects of their
explosion (fig. 98).
Header. Sandbag, stone, or brick laid with its long
dimensions at right angles to the face of a wall.
Impact velocity. Speed of a projectile at the moment of striking.
Incline. An ascending or descending gallery (fig.

98).
MasL-hour. The amount of work an average man can
do in one hour.
Outrigger trench. Special excavations required forthe outriggers of the 9(0-mm antiaircraft gun.
Perforation. The passage of a missile completely
through an object.
Picket. A stake of wood, wrought iron, or steel usedin constructing revetments and wire obstacles.
Rabbet. A groove or notch cut in one timber member to aid in joining it to another.
Scabbing. The breaking' off of fragments on theinside of a wall of hard material due to the impact or
explosion of a projectile on the outside.
218

Shaft. A vertical opening of limited cross sectionused for ventilating underground shelters and as an
emergency exit.
Shaft cases. Standard size frameworks used to line
a shaft.
Shaft frames. Frameworks holding in place sheeting used to line a shaft.
Sheeting. Planks used to line a gallery or shaft.
Slope. The measure of an incline, wall, or ramp interms of the ratio of vertical rise in a given horizontal
distance to that horizontal distance.
Special trench. A trench, 2 feet wide or less andfrom 3 to 5 feet deep, used primarily for protection of
personnel at artillery and rear installations (fig. 39).
Stabilizedsoil. Soil hardened by addition of a bindersuch as cement.

Standard trench. Trench of uniform cross sectionthat can be used either as a fire or communication trench(fig. 400 and ().
Stretcher. Sandbag laid with its long dimension
parallel to the face of a wall.
Sump. A pit in the bottom of an excavation to collect drain water so it can be pumped or bailed out.
Thin natural screen. Natural growth left in frontof entrenchments and emplacements to aid in concealing them.
Trail support. A log or other object placed under atrail spade of an artillery piece to provide additional
resistance to recoil (fig. 52).
T'rench boards. Flooring used in trenches (fig. 41).

219

APPENDIX IIEFFECTS OF BOMBS AND
PROJECTILES
1. PURPOSE. Fortifications are designed primarily
to withstand effects of bombs and projectiles. The degree of protection provided is dependent upon the time.
materials, and tools available and the types of bombs
and projectiles likely to be used. This appendix is a
guide to be followed in designing protective walls andcovers of fortifications. It describes the effects of various classes of bombs and projectiles, and indicates the
thickness of different materials required to protect
against these effects.
2. CLASSES OF EFFECTS. The action of bombs
and projectiles striking their targets may be considered
under the following:a. Explosion upon impact. Bombs and projectiles
that contain explosives and have instantaneous fuzes
explode upon striking any surface, and are used primarily against personnel above ground level. Walls andcover thick enough to resist blast and penetration offragments give adequate protection.
b. Penetration. Small arms and other direct-fireweapons whose projectiles do not contain an explosive
charge depend upon perforation and scabbing for theireffect. The depth of penetration depends upon striking
velocity, size, shape, and weight of the projectiles,
and upon the material they strike. Adequate protection can be obtained by getting below ground level orbehind walls thick enough to resist penetration.
220

e. Penetration and explosion.

Bombs and explo-

sive projectiles equipped with delayed-action fuzes combine the effects of penetration and rupture from
explosion. Adequate protection requires cover andwalls thick enough to resist penetration plus rupture andfloors thick enough to resist rupture.
3. PROTECTIVE THICKNESS. Protective thickness
is that thickness of a material which is required to protect against any or all of the effects described in paragraph 2. Until quite recently there had been a scarcity
of data on protective thickness. An extensive program of tests is being followed, but results are not available for inclusion in this manual. The figures given
in tables XXII, XXIII, and XXIV are approximations
and are not necessarily minimum safe figures. They
are based upon empirical formulas checked against suchtests as previously were made, and contain a factor ofsafety large enough to give the indicated protection
under ordinary conditions.

Figures are given for

typical soils and other materials found under field
conditions.

Ss397

4--4-15

221

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APPENDIX III
CONCRETE MACHINE-GUN
EMPLACEMENT
1. GENERAL. This appendix describes a square-type,concrete pill box which has been used in the theatreof operations. (See fig. 111.) It is simple, relatively
easy to construct, and may be modified to meet local
requirements.

2. PROTECTION.
a. The concrete pill box (fig.
111) protects against bomb splinters, shell fragments,and small-arms fire.
b. If steel plate is available, embrasures not being
used are covered by plates bolted into place. Otherwise, sandbags may be used to give partial protection.
3. CONSTRUCTION. Figure 111)Q (), and ( show
details of construction. Table XXV gives the bill ofmaterials required.
4. ARMAMENT. Either the light or heavy caliber .30
machine gun may be used in this emplacement. However, the light one is preferred because its general sizeand shape permit a smaller embrasure. Figure 1110
shows details of a pintle mount for the caliber .30
light machine gun. Field units with shop facilities
easily can make the necessary parts. Figure 111(shows an alternative embrasure design for the caliber.30 heavy machine gun. This design permits use of225the regular gun mount. One tripod leg projects
through the emplacement wall.
TABLm XXV.

Bill of materials for square-type concrete pill box(fig. 111)
Item

Concrete:(Cement)

Quantity-----------------_.-----.-(Sand) -............
(Stone)Reinforceriment:t. R. rails (30-pound) 9 feet 6 inches long_.
Bars, 14 inch round, 9 feet 6 inches longBars, M4inch round, 6 feet 6 inches long _*Bolts, machine, squarehead, with nut and 2
washers, -{inch round, 12 inches long.

11 cubic yards(66 sacks).
5 cubic yards.
10 cubic yards.
4.
54 pieces.
44 pieces.
20.**Ifleg-through-wall mounts are used, the following items are required:
Bolts, machine, squarehead, with nut and 2 washers Hjinch round, 12
inches long- -...................................
teel plate, 3 inches by inch by 3 inches -.........
Steel plate, 4 inhes by AI inch by lootS inehes .......................

226

6
2
2............
2

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SEE OETL FORON

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rILEVATION OF WALLS O

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S-O*

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5:-0

NUMERSEC.
BE VARIEDPEMBLIERASUFFOFTRUCAN

2-30 LB RMLS

_ '9-$

iGROnID LvtE

Plan ande
MBRSRE
SHOWN
0
I
3

LONG

CAL.
FOR 0 LIGHTM. OTHER TyS MAYBE USED.

i-e REIF SARSELEVATION OF WALLS GICD

Figre 111. Square-type concrete pill box.
EMBRASURE
SrOWN is FOR CAL.30 LIGHT MG OTHERTYPES MAY BE USED.
NUMBEROF EMBRASURESCAN BE VARIED.

® Plan aud elevation.
Figure 111. Square-type

concrete pill box.

227
227

TWO 30-LB. RAILS-

RiEiNF BRR

IO .-OCELEVCTIONOF WLINLLArSaOOLINE

PLITIIF UW.A

MOUN

PLAN OF EMBRASURE FOR CAL. 30 LIGHT MG

QJ Section AA, elevation and embrasure details.
Figure228

ll--Continued.

l.a BOLT TO
ANTISCABINGANCHOR
PLATE,IF USEDO

30-LB

p lREw BF
2ARS.

RALS 9b-C LONG'''-0.C. EACH WAY
SECTION ON LINE

WALL

/

B B!

I

I6L

%

I

WALLA
I

NT

ISOMETRIC VIEW

® Embrasure detail and isometric view.
Figure 111-Continued.

229

BUIN
PINPiNTLETO ;LOOK KEY

PNTLE LOCSECTION ON. LINE

D"Di

SECT!ON ON LINE "E E"(

Detail of pintle mount for caliber .30 light machine gun.
Figure 111-Continued.

230

' REINFI
BARS
10' 0 C EACH WAY

1" BOLTS

,
7

PLN
PLAN

6'

i

6.

.

12"· SOL

.

.
.i'-0

REJNFGONL
G.C.

INSIDE ELEVATION

4-,_o"LGNRAILS

V-CC'

PLATE I:G' LONG

" 2'3' pLATE

REINF OAIS
10' . C.
CE
H WAY-SECTION ON LINE A A"SHOWINGMG IN POSITION) Alternative embrasure, leg-through-wall mount.
Figure 111-Cbntinued.

231

APPENDIX IV
40-MM ANTIAIRCRAFT TOWER
1. PURPOSE. The purpose of the 40-mm antiaircraft tower (fig. 112 (0) is to place small-caliber (40-mm
and under) antiaircraft guns at a height from which
they may fire effectively at all positive angles of elevation through a traverse of 2900. The installation sites
are so chosen that the weapons grouped for defense ofan area are mutually supporting. For details for the

40-mm gun tower, see figure 112 ®, ®,( 0,, and ®,and table XXVI; for the director tower, see figures 113

and 114 (, ®, and., and table XXVII; and for theobservation tower, see figure 115 (XXVIII.

and (,and table

2. DESIGN. a. The structure is composed of two
separate towers 2 feet apart. The director, which is on
one tower, is not affected by vibrations set up when the
gun is fired on the other. A cantilever type footbridge
extends from the director tower to 2 inches above thegun tower.
b. The structure is designed to support its own
weight plus the 40-mm gun and mount, caliber .50 machine gun and mount, director, crew, ammunition, andthe vibration caused by firing the 40-mm gun. The
power plant is placed on the ground.
e. The concrete footings are designed to carry theload on soils with a bearing power of 1,000 pounds ormore per square foot. When soil has less bearing

232

GAN
pIaTFORMI

UPPERSECTION
OFiFILTOOROPOTWA DS.%C~CRETESTAIR
FOOTINGa( Isonmetric view.
FoiaGm 112. Forty-foot towers for 40-mm antiaircraft gun.

233

UPPERSECTONOFRAILTODROPOUTWARO

ZtxRALING'BOLT
OaJNECTCRS

4DETAIL A

4-BOVLLTS
B t

DETAIl54
sPOST,

'

DETAL

'4

I'

EVATION (STAIR SE)

4S'DETAIL

2

(SE

T

VI

.x4

RAILINGEAiL D (FRONTViEW)

ow-s

~

slit

® Elevation stair, side ad details.
Figure 112-Continued.

234

STRJNGER4,f

4' POSTS-

ANCHORRODS

7OALTTS
EI-0

Ih.

BENT

WDE*

'
402'

DETAIL F

BOLTS
PANL

CREWS
SECTION
pETAIL OF STAIR BRACEL-'

CONCRETE
OOTIN
TION
SIDE ELEVA
i
4--.

DETAIL OF CENTER STAIR POST FTG.

(

SPLICE DETAILSSide elevation and details.
Figure 112-Continued.

235

UINPLATFO

IRM
fj

2I?"

_3K
I*..
TREADS .,,±l:,LO-- 3dLArr~4"

3d LANDING SPLICE

5*1

J3flID7I2'$Lt

2TRINGER

2J

-3T

N

TREADS
TREADS~S

BOOM

i

2
IIN
¢/ AG--3

_~

E-

4

T/

24 L.
LAN

'T;
312-r-rO/,-- 4-,' - -iij " &BPOSTSTRINGER

14

2'.6' RAILING
L

1

ID?

ELEVATION (OPPOSITE STAIR SIDE)CANTILEVEREALL STRINGERS
2.'s

-J

4,.'
4-'.

O,

LANDING
Vi.Lx
3 ,-O CLAMP

fLTS

STRINEROIST
LAMP
SEC.D-OD(

Elevation (opposite stair side) and details.
Figure 112-Continued.

236

12'STIMI

L

143

.5

rd
1

N

OF
ANCHORPLROOS

T FOUFTOr

N 2 _ G'
1 6 I ,9 4 hi2SI-

PLTFORM566397-4N 16

566397'-4--61- l

ILCA

k'

'
+

GU N A N CH O R-P
GUN AINCHOR-A2

237

CC PLATE
6-4,

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7--i

V

JOIST FILLER BLOCKZ-;'PSN'JOSrST

STRUT

PO

.

1,

EXTENSIONS.

$TRUTSLANDING JOIST
JOIST

4-x
RAIL POST
3·g^r1

'-OC,

POST

s4s'6

LANCINGTHIRD LANDING
OF THIRD
PLAN OFFRAMING PLAN
FRAMINGJOIST EXTENSIONPLICE PLATEFAMINPIECESECOND238

FING-O.

LANDING SIMILAR-REVERSED

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241TABLE XXVI.

Bill of materialsfor 40-mm antiaircraftgtun
tower-Continued
Hardware list-Continued

Item

Size

Galvanized strap hinges--Pl. washers (square cut or
standard 0. G.).

8"_

3" x 3" x

Quantity.-..................

.---------'

20

433

20d
.-...............
10 lb.
Do.............
16d ------------------15 lb.
Standard double wood 300-lb. capacity -------.
1
block and fall.
Siemans-Martin 7-strand T"---------------228 ft.
galvanized wire.
Split ring connectors -.
4" .------------------..
592
Shear plates (mal. iron)....
4-"...................
54
Nails-------------------

Footing and deadmen materials list
Item

Quantity

Cement --------------------------------20 barrels.
Sand -..
.......................
7 cubic yards.
Gravel (1%" maximum).-..
10 cubic yards.
Reinforcing rods, W" x 17' 6" footings ----12.
Reinforcing rods, I" x 5' 8" deadmen----20.
16.
Reinforcing ties, Y%"x 3' 0", deadmen ----.
4.
Channels for deadmen, 3", 5 lb. x 2' 0"
Galvanized eyebolts, %/" x 7' 6"-----------4.

power, the footings must be redesigned. The elevationof the footings of both towers is the same regardless ofground features at the site. Footings are poured longenough beforehand.to allow concrete to acquire fullstrength before erection of the tower starts. This time
may be lessened appreciably by use of high earlystrength cement. (For information on bearing power
and footing design see FAM 545.)

244

d. The effective height of the gun tower is 40 feetand of the director tower, 41 feet. The gun tower,
built in 10-foot vertical sections, may be lowered byomitting one or both middle sections. The director
tower, similarly designed, may be lowered in the sameway.
e. The necessary stability for the gun is obtained byusing split-ring connectors, blocking between crossbracing, and guy lines.
f. The permanent ammunition shelter (figure 116
and table XXIX) is placed on the deck immediately
under the gun platform. The sides are covered with
1-inch tongue-and-groove sheathing and tarpaper toprotect the ammunition from the weather. An ammunition hoist may be provided as a permanent part of
the tower by extending the two outside stringers on theside of the stairway and attaching a block near the end.
g. An alternative design of ammunition shelter (fig.
117 (i and (i) and table XXX) is smaller than the regular shelter. Because it is smaller and has a simpler
design it is easier to erect. It can be built within thetower in place of the other shelter, or on the ground as
an extra shelter.
3. CONSTRUCTION. There are two common methods of constructing the towers:
a. If hoisting machinery is not available, erect thedirector tower first and use it as a scaffold to hoist thelarger members of the gun tower.
b. If hoisting machinery is available, erect towers
simultaneously, piece by piece.

245

0,~.~ALL WIRE GUYISLOPEDO
ANGLE
WITH TOWER.

Om.P CONCRETESCHEMATIC
OF

GUN

TOER

O CA
O

TOE

c

5.O

;

\

PLAN SHOWING RELATIVE POSITIONTOWERS, GUYS. AND DEADMENSAOCILL 5 TAIP

GRO,"U:NDj

frI:--O

2'8-.

/TLINESGROUNDLINE

EXCAVATIONBl'-SECTION '8-vE

I0. ,?;-,3-

F

7'-O--

1
DE - -I -DETAILS

PLAN
OF TYPICAL'DETAILDEADMAN (BEFORE

SjREILRODS

3-5B,,BCOANNELCSACKFILLING)

Schematic plan of 40 -mm gun tower, adjacent machine-gun tower, and details of typical deadman.

FIGUBa 113.

246

6.62
G
BOLTSSTD"°!
1 2 8 rLOORIIY~,..
'OZIHEARlONTS
i

SECTION

A--A"

.

..
T

.:

TRALIN2

t6·BCE
X
RACES

°

ST
SPL

S

-

Cx, POSTS

TAI .~~~~~~ 1A T.L\TOR
4 TT 1BE
TSEp
oFrf&TOP .FRONT--,.

ELEVATION

Front elevation and details.
FbeunE 114.

Forty-one-foot tower for director and caliber .60
machine gun.

247
247

4x64
' G' STRUTS

3'S'';.·i~i

PLAN OF DETAIL

FO
STRU

4%c

1..1 . [..I*RO

B
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EYESeOLrT-3^41-'.

L 3

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3E;/6'POSTSDETAIL.'NOLES FOR
fLAG SCREWS

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6-S_

,;V-

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,o0-o0

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101'-

-

CONCRETE FOOTLNGSSBOLTSANCHORV SITRUTS/t

ON
I
31-O.2Mi.

FOUNDATION PLAN

CONC+FTh,·

LLI__J

SiDE ELEVATION(D
and details.
® Side elevation aud
Figure 114-Continued.

248,

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RAILING

P,'FLYWOOD

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251

TABLE XXVII.

Bill of materialsfor director tower-Continued
Hardware list
Quantity

sime

Item
Carriage bolts completewith nuts and washers.
-}"
Do-Do -----withnuts Machine bolts
Do->a"
Do-DoEye bolts
Wire nails....
Do ..
Anchor bolts -.
--- Angles -.. ------.
Do ..
Split ring connectorsShear plate connectors- ...
Plate washers (square or
standard 0. G.).

Guy clamps--------------

3"

x 9"_
-12

"

12

............

X x 8"'
"
_%"

4
6
12

x 6"-.....
1'3"
1 '2
x 12"
x 9Y"-sox 1'2"

160

"
%"
6d5
----16d . --- .....
.........
.......
4" A x 3'0"4" x 7" x %" x 5" long_3" x 5" x Y%" x 4" long
Q-_______.___-_.
2y¼"
..
.....
2%.-..
3"------------%Y" 4 x

6lb.
55---lb.
12
12
4
360
12
524

24

"

" shackle ends ------.-. .
.
Turnbuckles...........- %Thimbles --------------.
.-7-strand galvanized wire_- %"612
360 ft.

Footings and deadmen materials list
Item

Quantity

Cement -..............
Sand --------------....
Gravel (134" maximum) -.
Reinforcing rods, 34" A x 17' 6" (ftgs.) ----x 5' 8" (deadmen)
Reinforcing rods, 54"
Reinforcing ties, A" 4 x 3' 0" (deadmen) -Channels for deadmen, 3", 5-pound x 2' 0"_.
Galvanized eyebolts, %'" 4 x 7' 6"-

10 barrels.
5 cubic yards.
6 cubic yards.
8S.
30.
24.
6.
6.
....

252

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Elevations.

Figure
t
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254

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TABLE XXVIII. Bill of materialsfor observation tower--Con.
Hardware list
Item
Carriage

bolts

-----

Do...
Do ---------------

Quantity.
.-4" 9 x 6-"...........

6

4"completewlnuts and washers.
Do-

Size
x 6"

. " ....x 455" __.__._._-16" o x 7"r-- _-____-__

Machine bolts complete%,"
w/nuts and washers.
Do --------_- '4x 92" _._.____.__"

x 8"_._.
- ----", x 6%" ___------Do -_-Do.........

-

_

__-

2

x 7%"_-___._____.-.......... "'x 2'8"'.------..-.., ~ 4 x_-----.----8"
.
.2Y"
-_150
.-..
2%-" _ _-.

Anchor bolts
Eyebolts Split rings -_Shear plates

Angles ___-

_

4
2

74
6
8
4
14

3%" x 5" x %" x 3%"

8

long.
Do ----_ .
...3%" x 5" x i" x 4" long_.
4
Butt hinges ----- _-------5" x 5"-...
_____-._
2
Roll roofing -8----_.._._
36" wide/108 square feet__
I rollLag screws. _ . .__ "
x 3"
8
Nails
.-._..._...
16d_--- _-_------------10 lb.
Do . __........
10d.--.
_......... .....
10 lb.
Do...
..........8d.-.
................
5 lb.
Roof tacks_-----.....
5-pound box_----------1 box
Turnbuckles.-----------" shackle ends -__._.
4
Thimbles.------------6" ..
_- ._.__._
8
Wire clips
5 6," __
3....
.-....
___ _..
16
7-strand galvanized wire -" -- ._------------180 ft.
Footing and deadmen materials list
Item

Quantity

Cement ---------- ---- -- __ ____-Sand -___-.
Gravel (134" maximum) _____.-_._....
Reinforcing rods, %'" o x 5' 8", deadmen-Reinforcing ties, 34"O x 3' 0", deadmen-Channels for deadmen, 3" 5 pounds x 2' 0"Galvanized eyebolts, ){"~ x 7' 6" ----------

0.74 barrel.
0.23 cubic yard.
0.45 cubic yard.
20.
16.
4.
4.

257

SLPOST
4,'

73

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;

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116.

g=

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Permanent ammunition shelter for 40---.- '

5-

SECTIOSE-TIO'1
N 'A-A'

,

'-

4

6mm'

F

2

E4TTHIN-'I' 6 VERTICL6
BOARDS-

Flaotu258

116.

Permanent ammunition shelter for 40 mm
antiaircraft gun tower.

-e .

0 vn

.,

Z'~d
EmaifjI~N~CddONdN
25

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259
' 2e9

TABLE XXIX. Bill of materials for permanent ammunition

shelter-Continued

Hardware list
Item
Butt hinges -Do-_......

Size
.

3"
...........
x 3"--............

4" x 4"-.....

Galvanized roofing nails -------------------Nails-.................
20d -..............
Do------------l 16d ...........
Do .
8d -...........
............
Thumb latch--53/2"-1_--------Galvanized hooks and eyes
22" screw typeRoofing felt, 45-pound36".rolls -4

260

Quantity
' 16

3
5 lb.
10 lb.
10 lb.
20 lb.
1
16
rolls

'-

-6

3

-

-N

BIOGLSATH.4 IPNEW6
CARRIAAE

FLOC
LINE OF

0

9a

IeL'

PLATFORM

3.ll

5'-6-

......

TOGOTHTR
P
WITHH

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BOLTS

4

oc

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~NEL
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WITH " CARrateg

1: . r
_

_:::

BOLTS
o e

PANEL N.o

6

6-

.30_|

6

rPANEL NO.

PANELNO.2
,

.10.

PANEL
N 02

6

FRONT ELEVATIONI Plan, front elevation, and section
Figure 117.

Alternative ammunition shelter for 40-mm alotiaircraft glin tower.

261

ROOFINOFEUTOVER 1i,6

PITCH--IONI *2_ JLATFORF.TROOFSOHEATHIN

R16NT SIHE ELEVATION

I RI

l

SECTION'8-'

OORLTSFLUNE

AROOF FRAMING

FFTE

PLAN

DETAILD?..

ELEVATIONSECTION 'C-C'

DETAIL OF VENT

( Side elevation, roof-framing plan, and details
Figure 117-C-ontinued.

262

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X

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xj
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s= -> -~~>-' -_O O' O'ocO'oF'O'

0 0icotou qoZ ' b' b' '263

T'lLE XXX. Bill of malcrial for alternative ammunitiolb
shelter-Continued
Hardware list
Item

size

Quantity

'
35X"
..
36
Carriage bolts complete w/-%nuts and washers.
Do-"_x 6}"- ____._
24
.
5 lb.
Standard Roof nails, galvanized Nails--.
20d-----------------5 lb.
Do -----.....
_--- 168d.
.-....... 10 lb.
Do. ..........
8d.
. ...............
10 lb.
Butt hinge- _------.
3" x 3".-.
.........10
3.....
4. x 4"_
4"-..
Do-4
'
5 rolls...........
5_.6"Thumb latch and handle -.-.
...........
5 rolls
Roofing felt, 45-pound per 36" roll
roil.

264

INDEX
Paragraph
Aids to the study of terrain _________.___.___ 10, 11
Antiaircraft tower 40-MM_
-____
____
App. IV
Approach_... _ _ _____.______......... 83

Page
7
236
199

Bombs and projectiles, effects ofBreastworks and parapets ._....App. II
26

224
44

Camouflage .-.
_.
..............
_..-__-_-_ 21
Cave shelters, types --______________________
78
Chambers ____---___ ___________-----89
Classification __________...
___________. 2, 67, 79

34
183
218
1, 126,196. ____.........
. ___Considerations and requirements:
Tactical -_____________________________
68
128
Technical -_____ _______._____________
69
131
Considerations, limiting___._______________
13
23
Construction:
Materials standard… _________.__________
72
147
Types of -_____. ___.
…-----..
.........
74,76 157,165
Corridors _____...________...____..-_______
9
6
Cover, overhead -----------------------71
142
Critical terrain features --.
.…
.......---__--__
16
24
Definitions:
Glossary____________.
_____ ________ App. 1
Terrain.-.
...
...........
-4
Terrain evaluation .__._______.___._……
4
Direction, changing horizontally…
. _. .
...88
Disposal of spoil…_____________._________.___
23
Drainage -___-...-----_________________
24
Emplacements:
Antiaircraft……
.....
-__
Antiaircraft Artillery:
Fire unit _.
_________________ _.
Gun battery ________________________
Machine guns-…
._.._______ ._Miscellaneous..
___ ..
.65_.._
Requirements ----------------- ----- _Searchlight section _....... .....--Shelters ....... _.._-_______-___-...

53

221
3
3
......
215
36
37.........
89

62
115
61
104
64
121
__________
121
59
102
63
119
60
103

265

Emplacements-Continued.
Antitank gun:Paragraph37-MM __________________-____-________44
57-MM ____-______-______________--45
Field Artillery................----...49-57
Gun:
4.5-inch -____________________--------.
54
155-MM.
..........................
55
Howitzer:
105-MM _--------...-- -…-_----_______ 46, 54
155-MM -___----------------------54
Machine-gun emplacement, concrete ----App. III
Mortar:60-MM.-...................
_____
41
81-iM -___..
____....
42
Employment -___--------- - -_____________
28
Entrances____________________________________
82
Entrenchments and emplacements ____-________ 28-65
Excavation -------------------------------- 22,81

Page
75
76
86
89
96
81, 898922966.............
69
47
197
47
35, 196

Factors, terrain -------------------------6
4
Features of military importance…-____________.
11
7
Fire, clearing fields._____..._ _____________ _20
28
Foxholes ----------------------------- _-___ 31-33 48, 49.
52
Gallery, driving..
86 ....................
206
Gasprooflng ------------------------------ ____
70
135
Glossary -__________________-------__-_ App. I
221
Grades_-_____________..-...____------90
218
Gnns, machine, caliber .30_.---------._____
39,40
58, 62
Incline, driving with cases.…
.
. ................
84
199
Infantry entrenchments for hasty fortifications___ 30-36
48
Infantry weapon emplacements......-----_-___
37A46
58
Influence of terrain__________..___________
5 ..
3
Lay-out- ___________________________________-91
Line -... ___._-__----___________-------- 90

219
218

Machine-gun emplacement, concrete -. ______…
App. III
Maps and reconnaissance_..__.........._____
8
Materials:
Construction ____._........-…
--------72
Fortification ___-------------------..----.
.
19

299
6

266

147
28

Military aspects of terrain_-----

Paragraph15_-_____________

Page
24

7
36

6
55

91
Plans ___........_…_--_______…_______-______
50_____.__..............
Priority of construction…
Projectiles, effects of bombs_________._.____…
App. II
Protection:.
. ........27
Against tanks…-----..--------.
...... 51
Personnel ____________-__-__.____
3,12...-Purpose___-----------------------------

219
87
224

..
........
___._________.-____.
Objectives
Observation posts -...----…---------------_

Requirements
RevetmentsRifle, automaticRocket launcher.-.............................
.-...... .............
_-8------------______.._
.-.
.

45
87
3,23

29, 80 47, 196
39
25
38
58
69
.......................
43

Scope ____--_--------------------------66
126
Shaft, sinking…...............
…__….__-...__
85
203
Shelter:
8852.----------------------------.
Ammunition
Cave____ ______ _..-..
..............77-92
181.....-.
............... 75-76
165
Cut-and-cover _.
66-72
126
_
_
.___________.__.
General _______53
34
Individual provne_ _---------___.___
Surface ______.-.___..... -....
73-74
156
Slope, change. __________.-............. 87
214
Tactical study of terrain_ ______.-____._______ 12-17
18-27..........
.-. Technique, general fortification
3-17...
Terrain evaluation…__ _.................Tools- __....____._____.______-_____-___..
18
14
Topography, general -_...................-.......... App. IV
d------Tower, antiaircraft 40-MM…
Trenches:
35_____._.--.--.---------------Connecting
Special -___.____.
...................... 47
48
Standard _______-----------------------37-46......---------........--------------57
92.....................

Weapon emplacement, infantry....
Weapons platform .......- -.
Work, rate of

23
26
3
26
23
236
53
81
82
58
101
219

0
267