WD 1475-1 - AEF GAS MANUAL - Tactical Employment of Gases.pdf

7/25/2019 WD 1475-1 - AEF GAS MANUAL - Tactical Employment of Gases.pdf

1/29

O F F I C I A L

* " ' *

G A S M A N U A L

Parti

Tactical Employment of

Gases

G e n e r a l H e a d qu a rt e r *

A m e r ic a n E x p e d itio n a ry F o r c e s ,

March, 1919

VJ

MANSCE N A dA DE MK UBRARY

F c LeonardWoo d.

MO

S 4 7 3 2 8


2/29

GENERAL HEADQUARTERS

AMERICAN EXPEDITIONARY FORCES

March, 19W.

The "Gas Manual," in six parts, is approved and published

for the information and guidance of the American Expedition-

ary Forces, Although this m anual presents th* p r a d k e In the

American Expeditionary Forces ils publication is not intended

to cotivey approval for adopiion In the future military service

of the United States of any details of organization contained

herein .

BY

COMMAND OF GENERAL FEU&HING:

JAMES W. McANDnEW.

Chief of

Staff.

OFFICIAL:

ROBERT C. DAVIS,

Adjutant General,


3/29

C O N T E N T S

' a r t I Tac t ical Em plo ym en t of G ase s . ,A, E. F, No. H75-1 G-5

par t II-Use of Gas by the A r t i l l e r y . , . .A ,E . F ,N o

t

1475-3 G-5

Part H IU se of Gas by G as Tro op s A. E. F. No. 1475-3 G-5

P ar t VIU se of Gas by In fa nt ry A .E . F. No. 1475-4 G-5

Pa rt V Use of Gas by Air Service A. . F. No,1-175-5G-5

Hurt VI Defense Ag ainst Gas A, E . F . No . 1433 G-5

TABLE OF CONTENTS

P a r .

Im po r tanc e of Gas as W eapon in M il i tary O pe rat ion s 1

Chemical Subs tances Used in Mi l i t a ry Opera t ions :

Th ei r Phy s ica l Prop er t i es 4

Their Physiological Effect

M

5

Effect in Relat ion to Density of Gas and Time of

Ex po sure , 10

Action of Gaa Upon Release f rom C on tai ne rs . . .> .** . . * 13

Pers is tencies of Gases

H

, . . . .* 27

M ethoda of Pro ject io n of Gas 34

Emptoyment of Ch em ical Su hs taa ce s in Ta ctics 35

Special Appl icat ion of the Var ious Groups of Chemical Sub-

stances 47

W ho Use* Smoke 62

f s e of S m o ke i n O p e r a ti o n s - . . . . - 5 5

Smoke Screens 56

P ro te ctio n of T a nk s* * . . * . . . , 57


4/29


5/29

GAS MANUAL

PART

I

ACTICAL EMPLOYMENT OF GASES

IMPORTANCE OF GAS AS

A

WEAPON

1

IN MILITARY

OPERATIONS.

1.

The

in troduct ion

and

development

of the uae of gas in

military operations

has had n

marked effect

on the

act ion

and

employment

of

t roops

in

combat .

A

proper tact ical t ra in in g

now requires careful Instruction

not

only

in

measures

of de-

fense against gas. hut in tbc use ofgas against thet n t m y in

offensive and defensive ope rations . Be ginning in April, 1D15,

with the first successful useof gas in theform of a gas cloud

j)rojtete


6/29

G o *

Manual

PHYSICAL PROPERTIES.

4. The a o s t im portan t physical property Is tha t which de-

termines the "persistency" of the auhstanre when used in the

Held, Tin s property depends chiefly upon th e rap idit y of evapora-

tion, which may be roughly estimated from the boiling point

of the liquid. According to this crite rion, we m ay nam e the

following classes, giving the moat prom inen t exam ple of each :

GROUP I Substance s which are g&ses at ord ina ry tem pera-

tures (of low persistency)Phosgene.

GROUP IIModerately volatile liquids (of moderate persis-

tency)Chlorpicrin.

GROUP III Slightly volatile liquids (of high persistency)

Mustard "Gas,"

GROUP IVToxic smoke producersDiphenylchlorarslne.

(I ) Gates at ordinary temperatures (like phosgene)> when

released from containers, will be blown about by the air cur-

r e n t ; hence, if the a ir is relatively still* as when the wind

is low, or in a dense wood, such a gas may persist for some

time. On th e other hnnd

t

in the open, and when the wind is

blowing, it will be quickly dissip ated . Such a gas can be nscn

advantageo usly against positions to be attacked shortly after

the release of the gas.

(II)

Moderately volatile liquids

(like chlorplcrln), when

splashed upon the ground, will vaporize rather slowly, and will

continue to contam inate the air in the neighborhood. In woods

or in dugouts, or when the air is sHll. this contamination may

persist for co ns id er at e lengths of lim e. However, tha t portion

of the liquid which has vaporized is no more persistent than

the gases in Class I.

(III)

Slighttjj volatile liquids

(like mustard gas) will give

off their vapors still more slowly, so that an infected area will

rem ain dangerou sly infected for a grea ter length of tim e. How-

ever, it is difficult to get their vapors into the air in high con-

cen tratio ns. OnJy by brea king them Tip to form a mist can

high con cen tration s and rapid deadJy effects be realiz ed. Sub-

stance s of this class are accord ingly especially useful in ha r-

assing an enemy and In preventing him From attacking over

nreas drenche d w ith them It bus. In fact, been possible to

ascertain positions which the enemy expected to ftttack by

noting gaps left in territory otherwise heavily shelled with

mustard "fins."

(IV)

Toxic smoke producers (us

diphe uylchlo rarsine) are

anhstances which can be made to give a suspension of extremely

line partic les of poisonous ciust, or mists in th e ai r. Such

douds are no more persistent than those

eaQttd

by gases In

Class 1. Their thief valne liea in their ability to penetrate,

more or less, the enemy musks. Usually w hen the cloud has

settled npon the ground Ifae amount of vapor given off is to o


7/29

Uwt

of

naH l

u a v e ttn

^

t o x

'

c L

'

f f e c t

-

S u c h

* " * "

O a

^ produced

hy the inhalation of Ihe particle* themselves while suspended

lu the n'r-

PHYSIOLOGICAL EFFECTS.

6

4

The toxic sub stanc es may be classified according to the

arc'domiuunt effects which they exert, with the understanding,

however, I ha t the action of any substa nce is not limite d to a

single tissue or group of tissues. Th us, a substan ce, th e vapor

of which causes injury to the respiratory passages, may, when

applied to the skin, cau se bl ist er in g. If the sole or chief use-

fulness of a substance in warfare depends upon its effect on

ihc respi rato ry trac t, it is classed as 11 res pir ato ry irr ita nt .

If its power to produce casualties is due to its action on the

skin, it is classed as a skin irr ita nt . If both actions are use -

ful, it is placed In bulb groups.

&/ Htspir : i tory Irr i ta nts . By far t i c greatest num ber of

substances thus far used injure the respiratory apparatus.

Three groups may be differentiated:

(a) Th ose wh ich ex ert th eir abief effects upoo the de lica te

jiu-m brants in Mie lun gs thro ug h wh ich oxygen passes from tht*

air int o tbe blood. The- m ain res ult of this inju ry is to cause

fluid to pass from the blood into the mi m ile iiir sacs a nd Lhus

to obs truct Hie oxygen supply to th e blo od . De ath from one

of these substances may be compared to death by drowning;

Uu: w ate r in w hich the victim d row ns being draw n into his

lungs from his own blood vessels, Ex am ple s: Phosgen e,

chlorine, chioi-picrln, diphosgene.

(h) Substances which Injure the m em bran es wh ich line the

air passages. During norm al l ife these me m branes insure pro-

tection lo the longs against mechanical injury by particles

which may be taken in with the air and against bacterial In-

Feciion, As a res ult of the actio n of subsU ncc n of thi s grou p

Iheir protective power is lost. Po rtio ns of the m em bran e ly^y

become swollen an d detached and may ping up the sm alle r

passages leading to the lung tissue, or the damaged tissue may

become the seat of bacterial infection, thus setting up bron-

chitis tiud pneum onia. Ex am ple s: Mustard gas, ethyld ichiora r-

sine.

Cc) Su bsta nce s wh ich affect chiefly ihe upp er air passage s,

i.e., the nose and throat- These substa nce s cause inten se pain

and discomfort h ut are not dan gerou s to life. They cause

sneezing, painful smarting of the nose and throftt. Intense

hf&dache, a feeling of severe constriction of the chest* and

vom iting. For varying periods after expos ure they may cause

general muscular weakness and dizziness, tosa of sensation in

parts of the body or evtn tran sitor y unconsciousness. Ex-

amples: Diplicnylchior&rsinc, diphenylcynrtarstni .

Tear Producers (lachrymaio.rs). . , Certain substances have

powerful efTecl upon the eyes, causing copious flowing of


8/29

Gas Manual Pnri

t

tears, followed by reddening and swelling of tbe eyes, pro-

ducing there by effective tem po rar y bli nd ne ss . These effects

are often produced

by

extremely minute quantit ies

of

tear

pro-

ducing substances* Larger qu an titie s of the same substances

usually

act as

lung irr i tants

as

wel l. Exa m ples : Brombenzyl-

cyanide, bromaeetone. ethyl idioacetuLe, chlorpk-rin.

8. Skin BJisterers

{vesicants),^

Certain suJislances have

a

pow erful ir ri ta ti ng effect upo n the skin, very much like that

produced by poison ivy. The same effect is produced upon alt

the surfaces

of the

body with which

the

substance

may

come

in contact, such as the eyes and (he breathing passages. Ac-

cordingly,

a

substa nce producing skin blistering will,

if in-

haled, also act as a powerful ir r i tant of the air passages. Ex-

ample: Mustard gas.

9. The following table includes the most important sub-

stances now In use in Chemical Warfare, grouped according

to persistency, witli brief indications

of

their physiological

ef-

fects. Lit t le attem pt

is

made

to

descrihe

the

odors,

as

Ibis

is

very difficult. However,

all who

have

any

responsibil i ty

in

connection with Cbcmical Warfare should become familiar with

the various odors by actual experience:

PROPERTIES OF SUBSTANCES USED IN CHEMICAL

WARFARE.

GROUP I

Gases

at

Ordinary Temperatures.

(Readily diss i-

pated by wi nd. No n-persistent,)

C h lo r in e ( B e r t tw l l l t e ) O r e c n l n b Y e l l m r

Ran,

L u na I rri tan t, d e ath

rnplri

or de

t o y e d . L e s s

to s i c t ii nn p f c ottge ne .

Of lor l ike- that

of

(C ,

Q,> (Ool-

C o l o r l e s s

gas,

e* jdlj- Ln ujr Irrltun t.

I lqulf lrf . rapidolef]it. Inimedl-

N.) fVloteiimti*> Uqalfletf. ntt death If neen-

tmted ; very lltto effect

If dilute. Rapid vi-

voverj with nn nftctr

GROUP U^M oderattlg Volatile Liquids. (Moderately pe rsis-

tent.)

Cbtorplcrin {P. B.) Liquid 1*an volntlte tlmn Lmap irrltJLtit. slipfitly

(B . F.I fSu- Liquid Iww Toifltlle Lung Irritant.

iGrafJi Cross i rbnn water.

fT#I* ifodt?rfitDly Tolntlip |1f]- Ncm? polftOTi

iDd tts-

lov 0i 1) fNew uld. p l n i to i T I r r it an t . Pro-

O r e e n U r r o s 3) duren pf i lu In th roat.

cheat

and

Liead,


9/29

Tac

Useof Gases

illSUghtlg Volatile Liquids. (Highly p ersisten t.)

rmo Jde (C, P o w e r f u l t e a r p r o d u c e r .

c a

ami

e f f e c t . )

I

S

i

vi-1 lo w

L lqn M, UolHiMf

ut

intDHCQt o do r w'lieu p ure .

O n r i l e o d o r f r o m i h e l l

b u r s t s .

A ir

I r rl l m n t .

fle*tii. and

d d d

DljiboJ

.

IV

Toxic Smoke Producers,

|ilf>rrsiDt IO, S o l i d , l nr l H l l g at 30*

t e rf l Ue , (Ittuv

C.

i ( 0 2

P.),

b o i l i n g

at

5 3 3

C.

f32.

IT,I

v a p o r

tn Hiuoke.

S. 3

of-

te n d e l a y e d

3

hour*

to

2 duy:-,

T i D l e n t p a l s

(a b(td, throat

c h t a t , wi t h

Stniiiar

u

' t il l ) ra n J oe ,

V,-t(i til e tlguld farm in g

s m tik e w i c b

o f

thu air.

ef f ect*

u D. A.,

but m ore po wcrfaL

L i t t l e t OXl C

o p f i

l r t e s

EFFECT

IN

RELATION

TO

DENSITY

OF GAS AND

TIME

OF

EXPOSURE.

ID.

The

degree

of the

physiological effects stated

in the

preceding paragraph depends

on

tht* time

of

exposure

and the

density of tliu gsis. It is evident that the more di lute the gas,

the greater

is the

t ime

of

exposure necessary

to

produce

an

equally toxic effect.

We may say

roughly that doubl ing

the

eoueenLnilion of agiven gas reduces thet ime of exposure- neces-

sary

to

kil l

by at

least

half, and

usually

by

more than

half.

This

is

very important

in

connection with tactical considera-

tions, because thi.- chief effectiveness of the gases of the non-

persistent type, like phosgene,

13

at tained through aurprisc-

L poisoning

the

enemy before

he is

able

to put on his

mask.

It

is exceedingly Important, from this standpoint, to surround

him suddenly with tfiis

of

sit in de nt con cen tration before

his

mask

is in

place.

11. The efFectivemjss of mus t a rd gas is par t ly due to the

fnct Lhtit

it

retains its* proportionate effectiveness

aj.

very

low

concent ra t ions The low concentration of one par t in 100,000

actiag

for 20

minutes produces

as

much effect

as the

high

con-

centration

of one

par t

in

10,000 acting

for 2

m inutes. This

is

also true to a large extent with chlorpicrin. Oo the other hand

T

the toxicity

of

hydrocyanic itcid

(the

toxic consti tuent

of Vin-

cennite), fulls

off

m uch more abru pt ly

as the

concentration

diminishes, so that a di lut ion is very soon reached at which

can

be

breathed almo st indefinitely w ith

no bad

resul ts .

12

The

following table gives

the

con centration s necessary

o produce death, or other characteristic effects, upon oxposure

or different leng ths

of

t i m e :


10/29

X

O

O

o

3

w

1

a

*

8

i

m &

5

@

o

el

1

A -f5 O r

4 ft *

i coo

;o

s

o o

S U7 O '^

g

a;

S fe

ft Ci u,

* *

5

.

5+ S

^

J K.

-

ill

- _

i

-

71 rt

t r si

Ei

^

9

O

S

o

1

|

r

| |

b

5

ft

ai

| |

h

n

1.L

D

g

d

3

o

o

o

1 1

O

SO

I

it

^

= =

?

D m


11/29

Use of Gun*


12/29

Gas Manual Part 1

ACTION

OF G S

UPON RELEASE FROM CONTAINERS

(1) Gas from Cylinders,

13 . When gas is liberated from a cylinder it IAblown along

the wind and as a result of the eddies set up by its passage over

the surface of the ground, it is mixed with air* The height of

the cloud, when the ground is cool mid the wind is nut too

high, is not very great, being limited largely by the height to

which the eddies extend. Over smooth ground this amounts

roughly to 30 feet at a distance of 100 yeards from the poim

of emission, increasing only slowly at greater distances.

14.

The cloud spreads laterally in the form of a IJLQ, as il-

lustrated in Figure U The angle of this spread may v&ry from

15 to 25 degrees. It is safe to take 20 degrees us an average.

This means that the width of the cloud aL any distance tram

the cylinder will he about 0.4 of the distance. An increase in

this angle seems to he favored by decreases inwind velocity and

by iniMvuse la the rate of emission of the gas. It is possible,

for practical purposes, to cakuiate thu concent ration uf gas in

the cloud at varying distances from ihe cylinder provided the

velocity of the wind and ttic rale of emission of gas are known.

The concentration will be gratest in the middle, decreasing

toward the edges, as indicated .by the shading in Figure 1. In-

creased wind velocity produces a proportionate decrease in tha-

concentration of the cloud. The average concentration at any

cross section of the cloud falls off somewhat more rapidly than

the increase of the distance from the cylinder. Thus, if the

concentration were one per cent at 50 yards, it would be some-

what less tbaD 0.5 per cent at 1UU yards, imd considerably less

than 0.U5 per cent at a thousand yards*

15.

If gas is emitted from the cylinders or groups of cyl-

inders at a distance from each other, each cloud will buhave as

above,

but at the point where they begin to iultrrsecl dilution

will become very slow, as illustrated by the intersecting lines

In Figure 2*

(2) Gas from Shells,

16*

As the clouds formed from bursting gas shells proceed

down tbe wind, the rate of speed Is roughly the same as for thu

fan shaped cylinder discharge, as shown in Figure 3, in wliicl>

A, B

t

and C represent horizontal cross sections of the cloud aL

the point of burst and at two later intervals, respectively.

Viewed from the side in elevation, these clouds arc seen to

spread out to a very great extent in the direction of travel.

This is due to the friction offered by the ground to the pas-

sage of the wind, that portion of the gas cloud closer to the

grouad being retarded the must. Figure 4 illustrates the appear-

ance of the cloud in elevation at the three points of its pai.li

shown above in Figure 3.

17, This longitudinal spreading of the cloud from a single

shell burst causes it to dilute much more rapidly, as it pro-


13/29

radical Us* of


14/29

14 Gas Manual Part 1

ceeds from the point of emission, than does the cloud from a

cylinder discharge. Of course, the retarding influence of the

ground operates in both coses, but the continuous supply of

gas from the cylinder tends to Keep up Lfae concentration. The

result of artillery fire is usually a succession of distinct clouds,

due to limitations in the rapidity of fire and to the dispersion

of the shots.

18.

It is very important, therefore, that hursts should be as

as possible to windward of the target, in order to sur-

round the t&fget with clouds of the maximum concent ration.

1$, Just as the behavior of the ckmd from a single cylinder

discharge enables one to predict the general behavior of the

cloud formed by the simultaneous discharge of a number of

cylinders, so the behavior of Lhe cloud from a single shell

burst, ns outlined above* allows the prediction of the effect of

gas shell fire in relation to wind, rates of fire and zones of

dispersion.

20 . Artillery "Gas Zones of Dispersion/

1

When gaa shells

are fired at a position the shells do not hurst simultaneously.

The zone of dispersion of a gun is the pattern produced upon

the ground by the impact of a Large liujaher of shells from a

single piece. This pattern is independent of tile rate of fire.

The individual gas clouds move at once with the wind from

the poiiiis of bottitj each growing and diluting as indicated hy

the above paragraphs. If, as is usually thii case, the shells dg

not fall simultaneously the effective zone of dispersion becomes

not a pattern on the ground hut a pattern in the air elongated

in Lhe direction of the wind. This elongation has the effect of

an increased dispersion, the increase being greater the greater

the velocity of the wind and the less the rate of lire. Figure 5

represents, in idealized fashion, tlie points of impact and the

sizes, position and concent rations of the clouds produced in a

wind blowing across the line pf fire. It is readily seen that

doubling the rate of flre will distribute the gas in rciughiy half

the area, producing thereby at least twice the concentration

and having fur more than twice the effect hi producing casual-

Lius. It is evident, also, that an increase in the wUid velocity

will distribute the gas over a larger area, decreasing the con-

centration of the cloud. (As shown in Figure 6 as compared

with Figure 5.)

21.

One t> the chief reasons for the

effectiveness of gas

is

the fact that the cloud of gas is pie sent for aii appreciable

Length of time ftfteg its emission from cylinder or shell and is

capable of producing casualties until the division becomes too

great, or until it is blown away*

22. Increased wind velocity reduces rapidly the length of

time that gas remains in the neighborhood. Gas is used most

effectively in wiuds under 3 meters per second. However, too

low A velocity is objectionable in the case of gas emitted near


15/29

Tactical U se of G ases

16


16/29

GasManualPart I

our own lines because of the. possibility of a variation in wind

direction bringing Ihc (?as back. Gas may be used in artillery

shell fire at longer ranges even when the enemy is tn wind-

ward by so adjusting the amount of gas used that the concen-

tration wj]l be harmless when it reaches our own lines.

23.

Tn order to kilt a man with t*as by surprise, it is acces-

sary to surround him with gas so concentrated that the small

fimount he must breafhr before getting his mask on is effective.

After hts mas is put on

t

the gascloud is of relatively small

effective ness. Even when the enemy is wearing his mask, how-

ever, it is desimhle to suhfect him to gas of high enough con-

centration to penetrate (he mask, especially the nearly ex-

hausted ones likely to be in possession of many of the enemy's

24. Effect of Temperature. When the ground is

warmer than the air, as when the snn is shining brightly, ver-

tical currents of air rising from the surface of the ground tire

generally produced, which have a great tendency to dissipate

as clouds. For this reason, j?as is used far more effectively

ftt night, or when the shy is overcast.

25.

Effort of Terrain. Tt is very difficult to obtain ftas

cloud, containing more than 0.1% of pap, for more than a very

short time after its release, and even this concentration rnpidly

diminishes. Therefore, there is hut little difference in physical

Tichsvior between a so-called gas cloud and so much air. Tts

density is but infinites maily greater, and H is subject to the

same movements as the surrounding nir. Tf it stays longer iti

a valley than on higher ground it is chiefly because the winds

blowing at htgher elevations nre not go strong in the valley,

26. Features of terrain which affect the movement of the

air affect the movement of gns clouds in almost the same way.

Tall grass, bashes, trees, buildings, etc., retard the niovemeiit

of air. and in nn increasing degree they retard the movement

at and retain gas clouds. Tn an attack following a gas bombard-

ment, more time must be allowed if a field of grain is in the

path than if short grass or ploughed fields intervene. Still

more time is, of course, necessary where bashes or trees are

present.

PERSISTENCIES OF GASES.

27.

Persistency of Liquids Upon the Ground. To know how

long the persistent substances wilt frifeet an area is very im-

portant. When ground ha* been evacuated in consequence of a

mustard gas bombardment the length of time which must

elapse before it can he occupied should be foTetotrt fts accurately

as possible. Tremendous advantage may be gained hy bcintf

able to estimate this period more accurately Iban can the enemy.

28.

The rate of evaporation of a liquid from Ihe ground Is

increased by increased wind velocity and especially by t*i-

cceased temperntnre, VTiMsrd gns In thp TVO/MIS. or -In '


17/29

V*e of Gasex

17

W

enther. will persist much longer than in the open or In

wiTidv weather. It will last longer on cold ground than on hot

ground- However, during a cold night, an mfeetcd area may

perhaps be traversed with little i&inijer provided the feet are

properly protected, whu-eas tlte following morning, after the

liUQ has -warniecl the ground, enough vnjmr may be given off

into t

e

fl

i

r

o s a

result of the increased evaporation to gas

severely aaynne traversing the area.

29.

Moisture produces {though very slowly) the chemical

{iL-cowipositiem of mustard gas so that it wilt persist for a

shorter tune iu moist soii than ia dry soil of equal tempera-

ture,

i

30.

If the mustard gas liquid is dispersed in very Hoe drop-

lets, it will disappear much more rapidly than when splashed

in large drops upon the ground.

31.

The following tahle will serve to give a rough idea of

the persistency which may be expected froio gasses as spread

Iv shell of the usual types:


18/29

E x :

o

s

E-i K

y =

e

It ha s ve ry HU1 od or.

(h) The abse nce of Im m ed iate effect,

(c) Its effectiveness in low con ce ntra tion s.

(d) Its persis tenc e.

49, Mustard Gnu.

(a) Use for ha ras sin g fire ogsilnst ba tte rie s, stron g poin ts,

woods, cross roads and enemy concentrations everywhere nt all

tim es p rior to attac kin g, {See c, d, mid e.)

(b) As is affects eyes, lung s, bod y and food, and per si sts

for days. It wears down the enemy moTale and vigor by forcing

constant wearing of the mask nnd the necessity of always tak-

ing other extensive precautions.

(c) In th e open it m ay be used when t he we athe r is clear

and w arm np to 3 doys before an attack.

(d) W hen weal her is cloudy and w arm , add 1 day to (c).

(e) W hen w ea the r is cold nnd espe cially cloudy, allow 4

to 7 days.

(f) In thick woods or brush heav ily bombarded with m us-

tard (as, allow 5 dnys In worm weafher and 7 days in cold

weather before attacking through them, except under special

c o n d i t i o n *

(g) A n Infected area may he crossed more snfely when the

ground is cold, as du rin g Itie night The nhove inte rva ls may

be reduced if this precaution is taken,

(h) Continue neu trnlizing and hara ssing fire against strong

points, ba tter y position s, cross roads and a ny possible concen-

tration points during the entire buttle, in accordance with the

schedules gfven In

(c), (6),

(el, and (fi. Th e flanks, whe re no

attack is to be made by mir troops, should he kept smothered

with mustard gfts to prevent the possibility of n flank counter-

attack,

(I) It m ay prove possible tn the future to change the hurs t

of mustard jras shell so as to diminish the persistency, allowing

earlier attack following Its use, and producing greater concen-

trations*

(j) W hen th e enemy succeeds In ha lti ng ou r attack at any

point, use mustard gas in accordance with the srhedules given

und er (e) nnd (fK an d in t he I nte rve nin g nertorf np to the

moment of the attack* pour fn pbossene with bath artillery and

G a

Troops. When the wind Is nnfavo rahle, I .

e

n

blowing to-

wa rd em** troo ps, m erely reduce th e am ou nt s sent over,

(k> Gas used as exp lained unde r f,|> f*

fl

vaJn&hJe weapon

to break up resistance In general, and TS especially v alua ble for

use a^afn^t enemy troops conce ntrated for co unte r-attack s.

fl) Thase of m usta rd gas mtiat be co ntinuou s on woods-

ravines, roaoj , villages, railroads, and nny other places where

troops can concentrate or where they must moTe.

th*

1

e n r rn T m n y n v is ii s h o w M h e t bo r o n j jh l y


24/29

24

Gas

Manual Part

I

(m) Used In this way, it should he very effective in inflict-

ing serious losses from hums, even if themask fully protects.

(n) Mustard gas can hv used in the offensive without en-

dangering our troops, beyrmd or to the flunks of an objective.

When the objective is a limited one, always allow cleftranee of

one mile as a safety factor in case tht wind should prove ad-

verse.

(o) Bombardments with mustard gas arc best carried out

at night, when tho ntmospheric conditions tire most likely to

be favorable, and, when, owing lo the difficulty of seeing whik-

wearing a respirator tht maximum amount of interference with

movement is caused. In addition, tht evacuation of shelled

areas is most difficult at night.

50, lirombenztjJcyftflide(lachrymalor)*

(a) Use anywhere to force immediate wearing of (he mask,

II is a powerful luchrymator, nnd very persistent, but not pois-

onous unless one is very close to a bursting shell- It is two to

three times as persistent as clilorpicrjn,

h) It is useful to save mustard gas, phosgene and chlor-

picrtn,

and stitl harass the enemy by forcing him to wear musks

For this purpose it is many times more effective than phos-

gene and chlorpicrin,


25/29


26/29

U a*

frL Tim follow ing tab le gives, a rough idea of Uic compara-

tive weight of phosphorous and the a p p r o xim ate efficiencies of

Ibe several

British

umoke producing devices now in use:

Dwicfi ,. right af PuitaphQraus

No, 21 Sm ok e i gi-eai value in modern m fau try tactic s, as it confers m auy

of

Ihti

adva ntages w hich are to be gained by conducting o pera -

tions at night, while few of Lhe disa dva ntag es are un s e a t. Us*

of smoke must hn vuiy uartfully plauucd in urdcr to avoid

sei-iou3 dis ad va nta ge s likfcJy to accrue un der co ud itio ns

favo rable Lo its use or if smok e be impi'uueriy em ploye d.

Smoke screens may be employed with one or more of the fol-

g ubje


27/29

Tactical Use of Gases

If troops are hidden in smoke clouds such clouds attract the

enemy's fire nnd are therefore dangerous; for this reason, smoke

screens intended to conceal concentrations should normally be

formed at some distance-about 400 yardsfrom the object to

be concealed.

In frontal screens, care must be exercised to place the screen

so thnt an enemy barrage laid on it will not catch advancing

troo ps. Sucli a screen should prefe rab ly b e placed on the enemy

trench system.

The necessity for anticipating the effect which a smoke cloud

will have in impeding our own observation and artillery fire

should

be

considered, as well as the possibility of troops being

hidden from our contact patrol airplanes.

When smoke is liberated on tbe flank of an assault, car*

should be taken, by defining permissible wind limits before-

hand, that the cloud does not

p a s s

across the front of the as-

saulting troops, as the latter attacking through sraoko are very

liable to lose direction.

When the use of u smoke screen in operation is contemplated,

the enemy should he educated to associate such a screen with

some object other than tire real nne, i\ g* be raay

t

by means of

a practice smoke screen, followed by no actioa, be led to sup-

pose that the object of the demonstration is to compel him to

expend ammunition uselessly.

It is obvious from Hie foregoing that it is of the utmost im-

portance that the use pf smokt should be systematic but varied

instead of casual and haphazard-

initiative at the critical momstit means the saving of valuable

lives and the avoidance of delay in the progress of the attack.

If this is to bt* cu ltiv ate d, and if m isus e an d w aste are to be pre-

vented, the moat careful training is required, not only of the in-

dividual, hut also of companies, battalions, and even brigades.

SMOKE SCREENS.

56.

The amount of smoke-producing material required to

Zotm a screen depends on a number of considerations, the most

important of which are as follows:

(a) The ex ten t of the screen. As a routfh guide it may be

assumed thnt the width of the screen should be from two to

three times the width of the object

to

be concealed (as seen

by observers from the points from which it is intended to

prevent observation) ,

(b) Du ration of th e screen.

(C) The direction of the w ind . A cross wind requ ires, as

;i rule. Less expenditure of smoke tlmn one at right angles

to (be front; and the difficulty of concealment increases if tht

direction of the wind is variable.


28/29

Gas

Manual

Part

1

(d) The

velocity

of

the

wind.

The density of the smoke

clond diminishes considerably

in

proportion as the Telocity

of the wind increases. In a wind of over 20 miles per hour

it is very difficult to form an opaque screen without excessive

expenditure of material,

(c) The number of directions from which the enemy can

obsen'e the object or area to Le concealed. The greater the

number of points from whEeh an object can he observed by

tjie

enemy,

the greater will be the extent of the screen required

and therefore of the amount of smoke producing substances

necessary to form it,

(f) The distance of the object from the enemy's observa-

tion posts. The greater this distance the

more

effective

the

smoke cloud will bi>.

In forming a screen with any form of smoke producer, it is

necessary for the formation of

the

smoke screen to be very

carefully organised* so that the best results may be obtained

with the greatest economy of material. All personnel required

for

providing smoke screens should be trained beforehand in

the use of the actual material which is to he employed and a

simple rehearsal is most valuable. The program which is to be

followi-d should stale in detail the rate of expenditure of the

smoke producing substances and should be given in writing 1o

the personnel at each smoke source.

PROTECTION OF TANKS.

57. Siiu't- the enemy artillery is the most dangerous advers-

ary of the tnnks, one of the vital conditions for the successful

operation of tanks is blinding the ground observation posts

which look out on the field of attack by means of a very dense

well regulated smoke screen. En front of ihe artillery in posi-

tion, a natural or artificial fog is a necessity to the tanks.

Batteries

assigned to support infantry, especially when latter

is supported by tanks, and artillery assigned to direct support

of tanks should have on hand at all times a sufficient supply

of smoke shells to take prompt advantage of opportunities for

its use. The efficacy of smoke screen properly placed in assist-

ing tanks to accomplish their mission has been amply demon-

strated

in

action.

Smoke shells should not be employed in the rolling barrage

alone. In different sections, notably that just cited, the method

of forming

n

"smoke cage," or box barrage, gave excellent

results. This method

consists

in establishing a smoke barrage

on all points from which the objective to be taken could be

seen

at

a distance of 500 to 600 meters. An enclosed area is

thus formed in which the infantry mid tanks may operate,

screened from the view

of

the enemy observers, without them-

selves being bothered hy lack of visibility within combat dis-

tance.


29/29

Use of Gases 29

rtAS AND SMOKE DURING A WITHDRAW AL OR OK STAB IL-

IZED FRONTS.

p. Gas and smoke on these fronts sho uld be

used

according

a the direction s heretofore given. On a retirem ent m axim um

of mustard gas should be used from close up to o ur

troops to as far back as the longest range guns will

reach.

Documents

WD 1475-1 - AEF GAS MANUAL - Tactical Employment of Gases.pdf