Notes on the Accuracy of Sound Ranging Locations

8/8/2019 Notes on the Accuracy of Sound Ranging Locations

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NOTE ON THE

ACCURACY OF SOUND RANGING

LOCATIONS

PRINTED AT

THE BASE PRINTING PLANT

29TH ENG •• U. S. ARMY

t9t8



l

NOTE ON THE ACCURACY OF SOUND

RANGING LOCATIONS

The Artillery Information Service has available for the location of new

enemy batteries and for the identification of old ones (a) aerial observation by

airplane, (b) aerial observation by captive balloons, (c) terrestrial observation

~y (l) the artillery forward observation posts, (2) by other terrestrial observers

In isolated posts, (3) by the groups of Flash Rangers, (d) locations by the

groups of Sound Rangers. It will be obsened that all these sources of observa-

tion are dependent on conditions of visibility excepting the sound ranging. In a

climate where any considerable proportron of the days are foggy it is evidentthat sound ranging becomes on many occasions of primary importance.

Locations by sound involve, however, procedures of such a technical and

• Complicated character that the layman is likely to look on the results obtained

by it with a certain suspicion. It is consequently of high importance to investi-

gate at every opportunity the actual degree of accuracy obtained under service

Conditions. This report herewith presented is concerned with a survey of cap-

tured German battery positions along the southern front of the St. Mihiel sali-

e~t in an area covered by two American sound ranging sections for six months

P~eceding the advance of September 12, 1918. The facts here presentedgiye a definite and reliable basis for the formation of conclusions on the general

'alue, of sound ranging and on the accuracy of location obtainable with it in

Geld operations.

. Sound Hanging in the United States Army is carried on by battalions of Xthe. 29th Engineers. The detachments are in all technical matters under the ..

direet control of G.2.C G.H.Q.-in tactical matters they are under the command

of the Comma~}(ling General of the Army Artillery. Sound ranging section

No. 1 was installed under the direction of G.2.C G.lI.Q. about March 11 in

Such a way as to cover the enemy territory between grids 350 and 360 (cast of

Apremont to west of Mort Mare). Section No.3 was installed about April 10

to cover from 358 to 3M (east of l\faizerais' to west of Regnieville).' The map

(No.1) attached hereto shows the area covered by the sections .

. The batteries dealt with by these sections may be divided according to Joca-

hon into the following groups from west to east-Mont See, Gargantua and

Mort Mare.Euvezin. The approximate limits of these groupings are shown

On the map (No.1). The nnmhcTl'l in black indicate the known batteries in

each group and serve as an index of the relative importance of the groups. In

this report the groups will be treated separately.

enOUI- l-1\IO~T SEe

This group included a numher of important and continuously active bat-

teries. The area density was, however, small so that there was a clear definition

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2 . ",'orE ON ACCURACY OF SOUND RANGING:

Totul

Actl". Within30 D.,..F05.380541093526482853

3050

of individual batteries and no difficulty arises in allocating any particular loca-tion to its proper battery. This group, therefore, affords a particularly goo.dopportunity for the study of accuracy of location. The batteries given in tinsgroup on the A.l.S. list issued September 8, 1918, are classified as followB:

List I-A.I.S. LocationsActh'e Within Active PrevloUI Suspected

60 Da,.. to 60 Day. Locations

]{16 0338 0952

1861 0846 0142

0940 0837

0552173712321440

1252

16561336

2773214622632957

lu addition to thcse listed thcre were certain positions temporarily occu.pied, 81 for example 1450, and several of the batteries reduced in the final analy.lis to suspected locations have been given in the S.RA. summaries of Marchand subsequent months as active.

The ].20,000 map attached (No.2) 8hows on it the locations of the variousbatteriel in the list given above. Only a few of the suspected locations areIhown since they do not for the most part correspond to true battery positions.

In this lame ~roup the total different locations made Ly S.R. No .. 1 he.tween March and September was 20, of which 8 were on railways and roads,

and one was found on examination to he a center of harassing fire of our ownpiecel picked up on several successive days by careless computers. Of perma.nent emplacements 'we have therefore given by S.R. a total of 11. These

comprille: 0336, 0638, 0947, 1446, 1861, 2955, 3050, 2353, 2648, 2262, 2356and J.150 (temporary).

Ust 2-S.R.S. LocationsA barrage list prepared from the S.n. datu would read as follows:

Actl". WItMa Actl .. Within Active I'revlou.

30 0.,.. 60 Da,.. to 60 Day.

08J6 .1{16 0947

~38 1861 2262

3050 145028:l32M3

. U81 3-8atteriea Really Active

An examination of the area immediately subsequent to the attack showedthat the following batteries only were probably active up to the night of attack:

0836, ()(H7, 3050 hprengminen-most recent occupation) ; 2855, 2853 (Sept. 5).

In additio~ during the period March to SeptemLer, 0638, 1861, 1446,

1~, 1336, 2648, 2362 and an unknown number of single gun transient po-lition. were certainly active at some time. No other Latt~ries were found that&bowed Iny eviden~e or activity thill year.

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NOTE ON ACCURACY OF SOUND RANG!NG 3

A critical comparison of these lists leads one to the conclusion that had, the artillery barrage sheets been built up on the sound ranging reports alone~hferesults would have been more satisfactory than was actually the case when~normation from all sources was included. One of the most active batteriesIn ~he area, 0947, although repeatedly reported by S.R., was not listed by the

~r~l11ery at all; the S.R. locations being assigned to 0846 because that wasvlslLle on the photographs. Similarly, Battery 0836, which was given by S.R.as active within 30 days and which was as a matter of fact very active up to~nd possibly including the night of our attack. is not listed at all unless itIs covered by 0935 or 0837; co-ordinates on which no batteries existed. Further,amongst the emplacements listed by the Artillery, 0940 and 0338 had clearly~ot ~een active in ye~rs. Battery 0940 was, in particular, plainly "?arke<lLSchlenstellung No. 45' and. was probably maintained to cover the finng of!ltteries from the adjacent railway as located by S.R. No. 1 at 0739 andnearby. Still further the majority of the "suspected locations" do not cor-respond to battery positions. They are mostly dug-outs, strong points, machine-

run posts, watering places for horses, etc. On examination, the suspectedOcations in this group were found to be as below:

0952 Watering place for horses.0142 Large camouflage-prohably a transient position in 191!l or 19]6.

0837 Nothing-probably meant for ()I')36.0552 Nothing-<lpen field-transient reeent positioJls Ht 04.~3.

1731 Peculiar deep dng-out in process of t'OJlstrnt'liOJl.

1232 Nothing.1440 Probably a misprint-top of Moot Sec.1252 Open field-nothing.

1656 Nothing.1336 Battery position, recent-77's.' Large strong point being built

close by.2773 Not examined.2146 Nothing-very old battery at 2246.2263 Transient emplacement occupied this year (part of old perma.

nent battery).2957 Not examined.

LWe will now consider the accuracy'of location of the individual bat.teries

y S.R. and also the accuracy of the individual locations of the par.t1cu)ar

batteries. Such general information as was collected during the exammatlonof the positions will be included here with the other data ..

Battery 0538 or 0638

Calibre. 77 and 10.5--determined from numerous wads in front of position'

and also from shells and casings.Protection. Emplacements concrete floors and wall~verhead wire and

brush-heavily concreted deep dug-outs adjacent to emplacement&-wellconstructed deep trench connections-tar paper houses in the woods !orquiet times. All walks and approaches fully camouflaged by drawmg

bushes together overhead.Direction of Fire. Mid-direction 200 mils east of south.Conununciations. Narrow gauge approach from rear-recently torn up. Guns

were pulled out at front by horses.Counter-battery. Heavy counter-battery by 240's and 150'8. Emplacement.

2 and 3 entirely destroyed. Entire position untenable. A great propor-tion of the shots )onp; and to the left (west). necenL



4NOTE ON ACCURACY OF SOUND RANGING

Y

233 850

233 885

xA.I.S. Coordinates (Sept. 8) •••••••••••••••••• 350 520

Mean S.R. Coordinates ••••••••••••••••••••••• 350 612

Surveyed Coordinates (G.2-C, 2nd Army) Center

of front •••••••••••••••• •••••••••••••••• 350585 233 370

This l.attery was reported 13 times by S.n. No. 1 with these accuracies

IQ. IOIr8. 2 RIt's. It was given as a 10.5 firing on llouconville, HamLu-court and Xivrsy. Last reported 8.4. Judging from the wads the twormplacements farthest to the east were most used. The surveyed co.

ordinates for the center of the front of these two emplacements are:Jt equals 350 625, y equals 233 882.

The t'oordinates above given arc shown on the appended 1.10,000 m?p square

(1"0. 1). The front edge of the woods in which this battery IS locatedcontain" a continuous line of emplacements of varying a~es but only thefour most easterly ones have heen in use this year. The camouflage on

the westerly l'mplaretnents had decayed so that those emplacements werethe more visihle. This battery, 0538, was reported active by S.u.O.T. 88three times during the period here considered Lut the emplacement wasDot villible from any of 88'8 posts and the flare could be seen only from.one PO~-that at Xivray. The individual locations are shown on' mapsquare (1"0. 2). . . . . '.

It ,,'ill be noted from the facts stated above that the ~ccuracy of the)ocat!on obtained hy S.H. is sufficiently good, bein(l; in fact ~better . th~n the)ocatlon arecpted hy the A.I.S. as resulting from photographIc restitut.JO.n orfrom othl'r information. We will now consider the accuracy of the indlVJdual

detl'rminations made by the S.R. group. The accuracy rating used by theAmericnn sections is as follows:

p jud~ed to be correct within 50 metersQ .. "100"It .. .. 150

RR-A 10<'8tion 'with a larp;er pos~ibtc error than 150 meters. An RR

maT be lIS good as a r or a Q but instrumental or weather conditions' or thelocation or the gun with reference to the area covered by the section are Buchthat a user ul e!\timate of the possible error cannot be given. : .

The 13 locations made of 0538 arc plotted on the appended map-square

(~o. 2). The elliptical areas marked P.Q.It are the arens within which the(l.Q.Jl locations ought respectively to fall. It will be observed' that all ofV the locali".o .... klle. I. accuracy Il,an claimcd. Th. line drawn nc"?,,

the fi~ure is the target to center of bllse chord line, along which the majoraxis of the ellip~ of S.It dispersion ought to lie. The major Llxis docs, as amatter of fact, lie rou~hly along this line.

Datl ....,. 2855 01 ' 2955

Calibre. rr. and .10.5's. Last occupied by 77's. Determined from wads andfrom ahells and cuinss. .

Protl'("tion. Emplacements concrete walts a~.I floors--Iarge enough for 150's.Overhcnd cover-{'amouflage only. ExcclJent, extensive Llnd well finisheddug-outll in reinforced concrete-very etrong-collnected throughout byconcrete tunnel"" . . .

Direcli()O of Fire. ~IiJ.direction 200 mi1ll west of lIouth.

Communications. Narrow gauge ruilway exclusively.

Counter-battery. Sli~ht-two or three Lur8t' only.

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NOTE ON ACCURACY OF SOUND RANGING 5

~.lS. Coordinates (Sept. 8) •••••••••••••••••• 352x890 235

Y520

rlrveyed Coordinates (G.2.C) • • • • • • • •• • • • • • •• 352 892 235 505R ean S.R. Coordinates ••••••••••••••••••••••• 352 895 . 235 525

emarks. This battery was reported by S.R. 1 a total' of 41 times with BC'

Itracies as follows-9Q's, 18R's, 20RR's. It was given as a 11 firing onT' ambucourt, Xivray, Bouconville. . .Ahe locations given above are plotted on map square No.3 attached hereto •.Ccuracy of the Individual Locations. The figure on map square No.4 shows

the individual locations on a 1-10,000 scale. It is again to be noted thatthe, accuracy claimed for each particular location is justified.

Battery 0836

Calibre. 11 and 10.5. Identified from wads. 10.5 wads found in front of em.P placements 1 and 2 only.

rotection. An extensive, well organized battery position apparently in use~p to the time of our attack. Six emplacements; but probably only twoIn recent use and not more than four at anyone time. Emplacementswith cement floors and sides to south and east, but without overheadprote~tion excepting for corrugated iron on light timber and camo~flflgeon wue. Excellent, deep concreted dug-outs for men in rear of josltlon,one in stage of partial construction. Other heavy log dug-outs an special

D' shelters for ammunition.Irection of Fire. Direction 450 mils west of south-extreme line of fire toleft.

Communications. Narrow gauge railway to center of position but guns were I

C . taken by horse through front of emplacements. . , .ounter.battery. None.

A.I.S. Coordinatcs. None unlcss 0935 is meant for this battery.x y

~urvcyed Coordinates (G.2-C) Emp. 1 350 819 233 624A;nter Front 350 835 233 585

nean S.R. Coordinates 350 835 233 633emarks. This battery was reported by S:R. 12 times with accuracies of 2Q's,SR's, SRR's. It was given as a 105 firing on llouconville and Xivray. Theposition contained a large amount of freshly fuzed 11 ammunition: Em.

placements 2 and 4, counting from the north, were almost certamlyAilnluse up to the night of our advance. Last reported by S.R. 8.21.

. 10.5 wads found in front of emplacements Nos. 1 and 2. •Diagrams. The coordinates given are shown on map square No. 9-. The In.

dividual locations are shown on map square No. 10.

Battery 0947

Calibre. 10.5 How., identified from wads and ammunition.Protection. Installation very similar to 0336. Eight emplacements, of which

. two had concrete walls and floors. The others were of wooden construc.

tion. Overhead cover in all cases, either camouflage or light splinter.proofs. The concrete emplacements had both been abandoned and ~t~eremplacements made close by, which were easier of access. The posItIon,i~ on the forward lip of a ateey ravine. Deep, safe dug-out8 were pro.vlded, opening on this ravine. In addition, there were tar.paper barracksfor general use. Special shelters for ammunition-position well dcslgned

and executed.




Direction of Fire. Mid-dircction 400 mils east of south.

Communications. Apparently supplied from first-class road in front of posi-tion. Pieces taken out hy horses from the front of the positions.

Counter-hattery. None.

A.I.S. Coordinates. None.

Calibre. 77'a-(rom 'Wads.

Protection •. An old emplacement, perhaps 1915 or 1916, heavily constructed oflo~s ~l!h deep, ""et. dug-outs alKo constructed of logs. Five emplacements.The IIVlOg quarters not u~d in Y~llrs. The two m08t easterly positions, theonee nearellt the road, fixed up for transient usage and recently used.Overhead camouflall:eof hranches on wire.

x ySurveyed Coordinates (S.R.lIdq.) ••••••.•••.••• 350 920 234 710 ,

~Iean 5.n. Coordinatcs 350 936 234 700

Remarks. In this battery emplacement8 2, 4,.7 and 8, counting from th!,""estern end, were occupied up to the night of our attack. Large quantI'ties of fuzed ammunition were found in the position. Pits 1 and 5 had beenabandoned for BOrnetime past. The concretcd pit8 .were. used. as 8en~ryposts or look-outs. S.R. 1 reported this battery acllve eIght times WIthaccuracies of 3Q'&,4R's and HUt Last rcported by S.R. on 6-28.

Diagrams•. The co-ordinates of this battery are shown on map square No. 11,

the individual locations on map square No. 12.

Battery 1446 or 1546

Calibre. 203 Russian hOWitzer. Identified from wads.

,Protection. Emplacements open-rough camouflall:e overhead. Pieces sunkabo1lt five feet. Very deep dug-outs for men lying between the emplace.ments. Excepting for low ammunition shelters no concrete work. F?uremplacements-the three easterly ones the most used. A low, umm.portant looking work. ,

Direction of Fire. 1600 mils east of south. ,

Communications. Narrow gauge railway approach from rear-recently tornup subsequent to counter-battcry. Guns pulled out at rear by horses. ,

Counter-battery. lIeavy dcstructive counter-battery, apparently by 2408.Three emplacements put out of action. Recent. ,

x yA.lS. Coordinates (~Iay 1) 351 500 234 600

(Scpt. 8) •••••••••••••••••••.••••••••••• 351 430 234 560

Surveyed Coordinates (C.2-C) '. 351 450 234 560Mean S.n. Coordinates 351 4{14 234 580

Remarks. This battery was report cd by S.n. 1 a total of 16 times, including

31"., 5Q:. and 7R'8. The coordinates ahove given are shown on maplfJuare l\o. S. The mean s.n. location will he seen to fall on the end ofthe blllt~ry ""h~re the more active pieces were. The battery lies on thereverse slope of Mont See and could not he located by any other agencythan S.~., or else from photographs. Particular interest attaches to Itbecause It Was the only large ralihre hattery in this arca. The S.R. reoports g~ve it as a 203 firing on RamLucourt, Xivray, llouconville andI1amonvllle. It 'was last r~ported July 6.

Accuracy of the Individual Locations. The individual locations are plotted onmap .quare No.6 attached hcreto.

ll~ttery 2853




Center of 6Center of activeemplacementsx y

352 620 2~i 775

D' . .!fectlOn of Fire. Nearly due south.

COmmupications. A narrow-gauge railway running down through position 2855.. Tins track was pulled up apparently before 2855 was built, that is to say,C many months ago. Transient pieces brought in along the road to the east.

Ounter-battery. Fairly heavy general counter-battery in neighborhood, but

mostly to the east and in front. It cannot be said that the position itselfWas counter-batteried at all.

x y

~.I.S. Coordinates • • •• 352 790 235 290

Mrveyed Coordinates (G-2.C) 352 820 235 280

eun S.n. Coordinates 352 830 235 290

Accuracy of the Individual Locations. ~he individual locations are plotted onmap square No.8, attached hereto.

Remarks. S.n. 1 reported this battery 14 times, giving 2 Q's, 5 R's and 7

RR's. It was reported as a 10.5 firing on Ramhucourt, Beaumont andSeicheprey and also as a 77 on the same targets. The 10.5 is reported in1!ay and June, the 77 in August. It is probable that the position was occu-Pled twice, as is here indicated. Last reported August 15, 1918. Papersfound in emp. show occupation on Sept. 5 by 77. The coordinates givenabove are shown on map square No.8. The individual locations are shownOn map slJuare No.7.

Emplacements Not PeMDaDently Occupied

. ~n this a;ea, as elsewhere, the enemy had numerous established, surveyed

pOS!tIonswhich he occupied only occasionally for special purposes of harass.nlent or for the support of raids.

Battery 2648

Calibre. Last used for 77's. Determined from wads.

Protection. Open emplacements with semi-circular breastworks. No shelt~rfor men. Guns when in place were camouflaged with loose branches •.SlXpositions. Numbers 4 and 6 counting from the west end were certamlyin recent use. Number 3 may have been used this year. The others had

not been used in years.Direction of Fire. About 250 mils east of south. .

Communications. Guns brought in along a dirt road from edge Bois Nouveau.

Counter-battery. Distributed shelling nearby-probably not directed at thisbattery.

x y

A.I.S. Coordinates •.....•••..•. 352 580 234 770Surveyed Coordinates •••••...... 352580 234765

Mean S.n. Coordinates •••••••.• 352 600 234 788

Remarks. S.R. 1 detected this battery in action August 2, August 3. ~Ugus~4, August 5, August 6 and August 7. It was reported as a 77 fir~g °dHambucourt Beaumont and Bois du Jury. 11 locations were made, locIu

ing 5 H's a~d 6 RH's.Diagrams. l\lap squares Nos. 14 and 15 show the data obtained on this battery.

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Dattery 1861

Calibre. Transient positions for both 77 and 10.5. Evidence-wads.

Protection. Open positions-wire and camouflage of branches overhead. ~hal.low trenches around gun positions and trench shelter for men. A smglepoor log shelter in the rear of the position. Four positions-Nos. 2 and 3

recently used .by 77's; No.4 last uscd by a 10.5.Direction of Fire. About 500 mils east of south.

Communications. First.class road immediately at the rcar of the position.

Counter.battery. Marks of recent counter.battery-probably during our push.

. One heavy burst near No. 2 position. A number of recent heavy burstsabout 100 to 150 meters short of battery.

• x yA.I.S. Coordinates 351 830 236 080

Surveyed Coordinates 351 930 236 070

Mean S.R. Coordinates 351 888 236 130

Remarks. S.R. 1 located this battery 5 times, 2 Q's, 2 R's and 1 R~. This isnot a sufficiently large number of independent locations to gIVe a first.dass lDean location. The surveyed location does not check with the map

detaiL From the map detail the y is 236 100. The coordinat~8 .o~ thelocations above shown are shown on map square No. 16. The mdivlduallocations are shown on map square No. 17.

Positions on Railways

The enemy made ntensive use of guns mounted on light railway cars.The degree of Success with which S.R. met in dealing with these guns can .be

judged from map square No. 20. The figure shows individual locations. wInchbelong in all probability to three firing positions at A, nand C. At A and ndefinite evidence was secured in the form of gun wads and shell cases of thefiring of pieces in these vicinities. The figure shows an of the scattered loca.tions oLtained Ly s.n. 1 in this particular area. The dates of locat.ion sho~vthat the guns remained active for three or four days in one position.. On .th~spart of the front the eremy had three centers of transient fire, of wInch tIllS IS

one. The others were the gap to the east of Mont See nnd the region of the[tang de Bailly. .

Extreme Flank Locations

• The area ",'hich a Sou~d Ranging Section is supposed to cover well is thatlYing between the perpendJculars erected at the ends of the Lase chord. Theselimit~are ~t by mathematical and physical COQRiderations. In our serv~ce thisarea IS extended to cover tl} a line one kilometer outside these perpendiculars,but beyond the~ lines no locations are reported as better than HH accuracy.That the exten8JOn to lkm. outside the perpendiculars is justified is proven bythe exc~llent location tlf batteries 0836, 06:l11 and 09'H, all of which lie in theextra lolom~ter. The locations made hy S.R. of battery 8929, which lies 3300meters o~l!llde the perpendiculars, 8erve to show the errors which may he

expected In extreme flank locations. "8929" was reported 5 times' three loca.tions hf'ing rated R's, although all should have bee~ reported RH's'to the artil.lery. The results follow: .

yA.I.S. location-Not recorded Ly 4th Corps

Surveyed lo('ation (center front) G.2.C •••••••• 348 930 232 960

Mean S.R. location 349 020 233 060

In examining the indh'idual locations as shown on map square No. 18, ex.treme errors in range .are to be noted. as would Le expected. but the line is



NOTE ON ACCURACY OF SOUND RANGING9

c~nhsi8tent so that in sparsely occupied areas a battery might thus be identified"ht a degree of precision similar to that which Flash Ranging and other~h servers get from single ray observations. The more, however, that one notese extensive UGe by the enemy of transient positions, the more it becomes

apparent that single ray observations of any kind not checked .by other evi.dence are valueless. In S.R. work it is therefore best to give no results at all,

evhen of RR rating, outside 1500 meters from the perpendiculars to the basecord.

Calibre. 150 howitzer.

Protection. Emplacements open overhead, excepting for camouflage. Breast-

. works, logs and dirt-recent. Excellent living quarters for men-smallshacks with dugouts behind. Deep tunnel shelters for ammunition. Large

quantities of ammunition on hand. I

Direction of Fire. Mid-direction about 650 mils south of west.

Communications. Dy road along the bed of an abandoned narrow.gauge railway.

Counter.battery. None.

Coordinates. See above.

Remarks. Installation remarkable in that the line of fire is only about 10degrees away from the line of the emplacements, The pieces fired verynearly over one another and over the shacks in which the men lived at the

distance of a few feet.

Th In this report all the locations made in the areas considered are given.ere are no selections and no omissions. The data therefore represent the

actual facts and do not reflect the beliefs or opinions of the compiler.

h

: The mean S.R. locations referred to in this report are weighted means, in

\V lch the weights are assigned on the basis of the rated Q, Rand RR

accuracies. P locations are arbitrarily rated 4; Q, 3; It. 2; RIt, 1.

The P, Q and R ratings as referring to anyone location give the computing

lOicer's critical estimate of the technical excellence of the determination. These,ofcntions result from a mathematical-physical procedure of such a nature that,I the wind and other corrections are properly applied and the atmospheriCConditions are properly evaluated, the final result must positively indicate theexact source of the sound. There are in practice always certain possible errors,

the limits of which must in each case be estimated by the computing officer.

1'-lthough the computing officer's estimate will be more or less valuable, depend.lng on his general grasp of the physical problem and on his knowledge of the

determining factors and of their mode of variation, the data here submitteddhow thut in our service these estimates were generally fairly true.- It is evi.ent that P locations average better than Q, Q's better than R, and R's better

t~an RR's, and that a location, judged by a competent computing officer iI? t~elight of known weather, instrument and line conditions to be within the l~ml.tsof error of one of these categories, is to a high probability actually wlthlD

these limits. There are, n.evert he less, possibilities for a considerably greate.r IV8!iation in anyone individual location than might be expected. These van.shons are due largely to an in8ufficiently accurate knowledge of the weather

conditions.

It is clear that since the nature of the errors involved is accidental. theaverage of any considerable numher of locations, in themselves inaccurat~, is.certain to be of a much higher degree of dependability. Four or five loc~tlon •.IDude under different weather conditions constitute a considerable number 10 thelense here used. and the mean of these four or five can he depended upon to be

~



10 . NOTE ON ACCURACY OF SOUND RANGING

clO!le to the true battery location, even though the constituent data are all of "n"accuracy. These fact! are fairly well demonstrated by the evidence exam!ned.This statement can be otherwi!le expressed by saying that five or more mde-pendent uu" locations enable us to place a battery with "P" accuracy or better.

It is because of these facts that Section Commanders in our service have beendirected to distinguish in orders of accuracy the accuracy to be ascribed,

ifthe judgment of the computing officer, to anyone location and the accuracy10determination of a battery position from a series of observations. The?lC erof accuracy of the mean position will, as above pointed out, be always hIgherthan that of the constituent data and can only properly be determined througha consideration of the number of independent values involved -in the mean. Abattery location should Le rated R on a single determination because of ourneces.~rj]y uncertain knowledge of the weather conditions, although the film

itself may be judgf'd P or Q. A "Q" can, however, safely be given to. th~weighted mean of four or five locations irrespective of the ratings of the mdl-vidunl determinations and a P can similarly be assij!;ned to the weighted .mea!!

of eight or ten locations. The attached data show that a P battery 10?atJonrIS

sa(e to 25 meters. The principal factor entering into the accuracy ratmg 0 abattery position is seen to be the numher of locations obtained of whateveraccuracy, Lut it will be understood that the giving of an order of accuracy to a

battery loc~tion cannot be reduced to a mere mechanical c0!lsi.derat!on of thdenumber of mdependent determinations involved, even though It IS mamly baseon this number. The grouping of the locations should he considered and shou~dbe (ound normal. A normal grouping is roughly elliptical with .an axial ratioof 1 to 3 or thereabouts. The major axis lies roughly on the lme, battery tocenter of base chord.

The batteries discussed in the group covered by this paper ~The ~ont See

group) are selected from this group as typical. Persons studym~ tIus reportcnn aa(ely accept the conclusions to which it leads without waiting for the

feports on other ~roups. There is no essential difference in the character 0the results obtained in the different group! or in the batteries of anyone group.

We can Bum up by sayinfl; that a single Sound Ranging location rated P,o or R is to a high degree of probability within the limits of error stated forthese ratings; that a mean Slund Ranging location comprising seven to te!1 ?rmore indiYidual determinations is to a considerable degree of certainty wlthm25 meters of the activity center of the Lattery. In consequence it is probably

tI -UAt to conclude that Slund Ranging is in fl;eneral practice more. dependable

) ((lr compiling lillts of active batteries and for detecting the active part of aJiven .battery, th~n any other agency. It should, however, he pointed o'!t t?atthe hIghly technIcal procedures involved and the breadth of general sCIentificknowledge required to l!:et results of this grade consistently, demand a highlyqualified, highly trained and experienced personnel and a properly handledapparatus of the general character of that in use by our sections.

The attention of readers of this report is directed to the fact that' theme~hod. u.sed for Joc!'ting active ba.teries by S.R. are not the ones made ~se(If In rangang o~r artillery. on an objective. The placing of the bursts relatIveto one another IS accomplIshed hy other procedures which enable us to refort,h. ",1. 'i•• po.ition. 10 • <on'ideroLly MgLer degree 01 '«nr.cy. It wi! heseen that a dispersion of locations of successive bursts, such as is shown o.nthe attached mllp squares, would be of 110 use in correcting artillery fire. ThiSdillpenion nsuhs from the dis8imilarity of weather conditions on different days.~e .n!luhs obtained from any. one battery at anyone time, roughly BpeakingWIthIn three or (our houn, Invariably check very closely indeed with oneanother; but thf"&e luue!l'live determinations do not appear on our records,heing looked upon as duplications. .




GROUP 2-GARGANTUA GROUP

J .The limits of the Gargantua group are shown on Map No. 1. This group,~y In the center of No. 1'8 base and contained a number of batteries-par."lcularly 3751, 3749, 3855 and 566Q-which, during February and March, wereiery troublesome to the American divisions facing them. S.R. No. 1 was

nstalled primarily to cover this group.The AJ.S. list for September 8th, 1918, classified these batteries as follows:

List No. I-A.I.S. LocationsSuspectedActive Previous

to 60 Days

3749

3453

3646

384644544148

425845475734

6062

Active Within

60 Days

375147585058

5061

54565463 .

5763

-two old hatteries-not active in &everal years-ruins.

Active Within

30 Days

346638554667475948685355

5369555655605561

46675355

5556

5560

32473853

4040493545564050

41054551

42625241

5668

53,57

505754525951

54745966

6157626663696639

6755

h Durin!!: the period March to September S.R. No. 1 located in this area 22attcries. These, classified according to activity, are given below:

List No. 2-S.R.S. LocationsActive Within Active Within Active Previous

30 Days 60 Days to 60 Daya

3466 3751 34534454 3855 36464868 4759 3846

5369 5357 39375660 5474 4258

5761 5457 5561

5763 5567 60623749

hOmittin~ any reference to the suspected locations it will be @cen.hat we

ave on the AJ.S. list, and not on the S.R.S. list, the following battenes:

. List No. 3.:.-0n A.I.S. But Not on S.R.S.30.Doy LIlt Remarka (baacd on examination of the arro& aubsequcnt to the

en"my retrroat)

-Anti-Aircraft not examined. • •-no trace of emplacements here-strong pomt In

trenches.'



12. NOTE ON ACCURACY OF SOUND RANGING

6().Da, Lie,

47585058

5061

5463PreYloua Lie,

41484547573-'1

R6mark.

-no trace of battery here-perhaps meant for 4759 A.A.-not examined.-not examined.

-nothing here-perhaps a battery in 1915-doubtful.

-old batte!'>' position-probably active.-not exammed.

-in front trenches-unlikely unless minenwerfer.

Remark.

-no battery here-recent active battery at 6366.-!10 battery in this vicinity.-an front linell.

-transient 77 position.

-no Lattery but probably transient pieces.

-no battery-tarp;et ranp;e perhaps. 0

-old. concreted destroyed emplacements-close to tran-

I.ent emplacements.-a heavy battery. considerably used probably within 30

daya-lS0 howitzers.

-dugO!'!t8 and barracks.

-nothing in thi8 vicinity.

-large dugout.

Remarka

-center of ten very active emplacements-covered by5560 on A.I.S. list.

-two. certain, transient positions in field-recent use-part of 5660 group.

-recent transient position-ammunition-spade marks.etc.

-suspected location of AJ.S.-not examined.-not examined-probably same as suspected 5668.-semi.transient position-Art. Stell. 106.

-??

Ust No. 4-On S.R.S. But Not on A.I.S.

5%6

615762666.369

66.196755

30.0., Lla'

S660

5761

"'.0.,L1a'

5357

5-17<\55675457

PreYlnua LIe,

3937

-old position-front trenchee--2 locations only-prob-ably minenwerfer.

It 'Will he 8f'enhere. 88 in the Mont Sec group. that a barrage list made up

from S.R. data alone would have been more reliable, effective and economicalthan the one actually used compiled from all 8ources~ The list of "suspectedlocations" 'W88 not examined in full' but such information as was collectedIhown below. •

SuaJH'Clf'd byA.I.S.

3247

38:"~4().10

49354,'}.')6

4350

4105455142625241S66853575057545259515474

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y

3749 353 675 234 910

3749 353 700 234 955

t W

h

e will no,,, proceed to give the detailed data referring to the more impor.

~nt aUeries of this group.

. Battery 3749-nattery 3751

C l'ba Ire. 77 and 10.5-From wads and old ammunition.

rotection. First-class emplacements-heavy co.ncrete and log fronts, logs setverticaily-strong concrete sides-camouflage roofs, strong concrete dugoutfor P.C.-tar paper barracks for men-No. 1 not so recently used, prob-ably had 10.5 in it last-Nos. 2,3 and 4 most recently used by 77, but 10.5wads in front of 3. Emplacements distributed as shown on Map-Nos. 1

D' and 2 form battery 3749-Nos. 3 and 4 battery 375l.

Irection of Fire. All four about 30 degrees east of south.

Communications. Narrow-gauge carefully camouflaged dow-n line of emplace.C ments about 20 meters in the rear--stops behind No.2.ounter-battery. Heavy and very effective recent counter-battery by 155's-

all four emplacements untenable, 1 and 2 practically destroyed. Severalshoots with 155 ranged by S.Il.S. No.1 on this battery.

x y x

A.I.S. Coordinates given as 77's-• 3751 353 740 235 065

Surveyed Coordinates (center) G-2-C-3751 353 745 235 050

Mean S.R. Coordinates-. 3751 353 755 235 079 3749 353 720 234 940

Remarks. Map squares Nos. 23 and 24.-a very active battery in March, April

and May-last reported-3749 on May 21st-3751 on JulY 23rd .. The~lIatteries apparently contained howitzers and guns at the same tIme 10

different emplacements.

Battery 3855

Calibre. 77. From wads, baskets and ammunition.Protection. Four recent 77 emplacements on ground-no protection-camou-

fl~ge on poles, in front of four very large, almost completed em.placement~WIth deep dugout at sides and full deep trench system connectmg Nos. I,2 and 3. No.4 by itself-not completed-never occupied. Nos. 1,2 and 3had been used recently by 77's-the new 77 emplacement. Nos. 2 a~d 3

were directly in the gun apertures of the big emplacements. To the r.l~ht,open, camouflaged position for a 15cm. How.. used considerably-no l!vJngquarters for men, but 200 meters in front is a very deep, extraordmarylarge dugout system for a large number of men-a very ex!>ensh'e piece of

work.

Direction of Fire. Five degrees east of south.

Communication. Narrow-gauge 150 meters in front. Ammuniti~n dump there.The guns were pulled out at front by horses.

Counter-battery. Considerable counter-battery in front-no 8<'rious effects on

battery.x y

. A.I.S. Coordinates (as a 77) •••••••.•..•.••.•• 353 760 235 4(.0

Surveyed Coordinates (center of front) G-2-C .•• 353 755 235 458

Mean S.n. Coordinates ••••••••••••••••••.•••• 353 787 235 460hemarks. Reported by S.R. 17 times-1 Q's, 6 R's and 4 RR's-last reported

88 a 71, and once 88 a 10.5 firing on Rambucourt and Beaumont-last



j

Battery 3466

Calibre. Anti-aircraft, probably 77 from shell baskets.

Protection. One weak dugout-no trace of emplacements, but sighting ba!sand other instruments in place-ammunition shelters of concrete slabs as 10

other anti-aircraft positions. .Communication. Oose to narrow-gauge.

Counter-battery. Whole area torn up with 240's or 270's. This counter-batterYfas almost undoubtedly intended fOf the important dump and network 0

roads at Etang Champrcz-short 400 to 500 meters-road crossinguntouched.

x yA.I.S. Coordinates ••••••••••••••.••••••••••••••••••••••• 353 400 236 600

Surveyed Coordinates. From map detail (instrument stand) 353 360 236 700Mean S.R. Coordinates ••••••••••••••••••••••••••••••••• 353 381 236 720

Remarks. Located by S.R. 32 times-4 Q's 16 R's, 12 RR's-given as an 'anti.aircraft-last reported September 3rd-first reported July 30th-very active.Map square No. 27.

IrOTE ON ACCURACY OF SOUND RANGING

reported August 2nd. An active battery area-difficult to be certain thatthe two short Q's are not from a position in front of 3855 and the twolong Q's from a position behind. The position behind had two 12cm.Belgian breech-loading rifled guns (Liege 1866) in it-a very old type If~un, almost certainly used, but probably not this year, and not mefe

laummies. Breech mechanism gone-still in place November 15th-otype 12cm. shrapnel fragments (red shell, five copper bands) not unusualin fields near Xivray and Rambucourt-may have been from these. guns--trees cut down in front of 3355 over a large area, say 5 acres, to gIve fieldof fire. Map squares Nos. 25 and 26.

J

Battery 4258Calibre. 77-from wads and baskets.

Protection. Open emplacements on ground level-camouflage of branches-no conlltruction excepting split log ammunition shelters-no living quarters,~xcelJen~ extensive, deep dugout settlement across the road, distance 50meters (Cargantua Lager'-men doubtless lived there.'

Direction of Fire. About 10 degrees east of 80uth. .

Communication. Along good road pa8sing position-narrow-gauge on the road.

Counter.balte..,. neavy. deNructive eounter.bultery to eu.t of po.i!io~ aUd

j

about emplacement No.4. Though no trace of this emplacement, It IS verydoubtful if there were but three to begin with.

x yA.I.S. Coordinates (as a 77) ••••.••••••••••••••.•...• 351 235 235 835

Surveyed Coordinates. From observation post <C-2-C) •. 354 215 235 835

Mean S.R. Coordinates to •• 354 190 235 849

Remaru. The three' locations as' shown here check well with each other, butthey do not check with the map detail for the position where the batterywna found by the compiler of this report by about 100 meter9-this mustbe further invelltigated. Reported by s.it 29 tirnes-l P 8 Q's, 16 H'8,4 ~~'" 8S 77, firing on Seicheprey, Xivray, Rambucourt ~nd Beaumont-:-ongJnlllly dl8C?Veredby S.R. 1 March 3rd-very active April let to Apnl19th-reoccupied June Sth to June 21st-last reported active June 21st-,Map af)usre 28.

I.

.

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x

35.1 8,10 236 860(Center Nos. 1

and 2)

C Battery 4759

Palibre. Long 77-from shell cases.

, rotection. Two emplacements on surface of ground-platform marks visible-guns when in position camouflaged with brush-no protection excepting~oncrete slahs for ammunition shelters-extensive living quarters (shacks)

In woods 75 meters.to west-one very deep, two entrance dugouts of recentreconstruction.

Direction of Fire. Trail marks gave mid-direction about 45 degrees east ofsouth. Position was apparently an anti-aircraft with special gun mountings.

COmm ..C UlllcatlOn. 30 meters to third-class road-ground marshy.

Ounter-battery. None.

A x Y

S.I.S. COQrdinates as an anti-aircraft •••••••••• 354 670 235 880

1\ urveyed Coordinates (center) G-2.C .•.•.•.•.. ,354 650 235 875

fean S. It. Coordinates ..•....••..•....••.••. 354 688 235 831Remarks. This position could only be found by a person of experience, as the'

traces had disappeared in the marshy ground-it is fairly clear that thesurveyors located some shelters in the rear of the position, describing themas "piles of brush" (see survey notes). The X coordinates of the batteryare therefore probably 354 680-interesting traces of instrument and tripodstands-board to rear of position marked "Flakstellung" (Anti-AircraftP?sition). J{eported by S.n.. 23 times-6 Q's, 16 R's, 1 RR, as an anti-aucraft-last reported July 15th-very active June 7th to June 15th-Mapsquare 28.

Battery 4868

Calibre. 77-from wads, cases and ammunition. ,

Protection. Well developed position in woods-four emplacements of logs andearth-very recent work-No. 4 not yet completed-Nos. 1 and 2 mostused-living quarters in rear-shacks-no good protection.

Direction of Fire.-Mid-direction of fire about 60 degrees south of east.

Communication. Curved spur of narrow-gauge well camouflaged with bushesdrawn together over it, in immediate rear of emplacements-push cars ~sed-supplied by dump on narrow-gauge on north edge of Etang de Lampmot

-dump at junction-this is one reason why Nos. 1 and 2 were used themOBt-guns pulled out at rear by horses.

Counter-battery. No counter-battery on position itself.

x y

A.l.S. Coordinates as a 77 •••..•.••• 354 830 236 832

Surveyed Coordinates ••.•.•.•...••• 35,1 870 236 880(Center No.4)

Mean s.n. Coordinates ••.....•..••. 354 850 236 820

Remarks. This battery was very active up to or during the night of our !ldvance,j~dging from the large amount of fused ammunition (pin type E.K.Z., et~..pm in place), piled beside the emplacement, and the recent blast. f!lark8o~ the bushes-large area of trees cut down to clear line of fi~e-on~~nallYdJKcoveredby S.H.. on April 7th-located 41 times, 1 P,.7 Q s, 20 It .s, 13HIt's. Given as a 77 firing on Mandres, Ilcaumont, Sclch('p~ey, ~J81 deJury and Bois de Jlazelle-very active from April 7th to Apnl 23r eSA

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active in May-very active again from June 15th to September ~rd-Iastreported on September 3rd. Considering the large number of 10catlOps,thefinal S.R. position does not check as well as might be expected, wIth ~hesurveyed position-there seems to be no reason to doubt the survey-unlIkemost of the lakes in the area, Lambepinot contained a considerable. amount

of water-it is fair to assume that this body of water, about one kIlomet~rin length, close in front of the battery, interfered with the s.n. results 10

the way here seen-Map S<luare29.

Battery 5369 .

Calibre. 10.5 and 15cm. lIow.-wads found-may be possible that 77's werealao at one time in the position-a transient emplacement, considerably used•

•Protection. Open wooden platforms-four positions-platforms torn up ~ndemplacements hard to locate-no living quarters or shelters e~ceptmgtrenches and ammunition shelters-very deep, and somewhat peculIar dug.outs under construction about 80 meters to southeast of battery.

Direction of Fire. About 30 degrees east of south.

Communication. Narrow-gauge in front-the same one that passes 4363-roadalso near by-guns taken in and out by horses. .

Counter-battery. None in position proper.

x yA.I.S. Coordinates as a 77 •••••••••••••••••••• 355 280 236 910Surveyed Coordinates, center of emplacements

found •• • •• • •• • • • • •• • • •• • • • • •• • • • • •• • • • •• 355 270 236 .890Mean S.R. Coordinates ••••••••••••••••••••••• 355 225 236 897

Remarks. The surveyors failed to find emplacements Nos. 1 and 2, as the pla;t.forms were torn up. These are shown on Map squares Nos. 7 and 8 I.nproper place, as determined by sub!lequent checking by the compiler of thISreport. Located by S.R. 9 times, 5 Q's, 3 R's, 1 RR-given sometimes .as 77~un, and other times as 10.5 lIow., firing on Bernicourt, Seicheprey, Xlvrav,Beaumont and Rambucourt-active May 28th to May 30th, June 1st toJune 15th. and lbt reported August 12th-Map square 30 and 31-,-thedugouts in front consisted of deep conical holes, perhaps I? to 20 feet

fiat at the bottom, with the deep du~outs going off from the bottom ofthe hole-.imilar ones near battery 5655 .in a minenwerfer strongpoint.

Battery 5660 (or 5560)

Calibre. 77-from wads and ammunition.

Protection. Open emplacements on surface-low breastworks in front-cam.oufla~e on poles overhead-no living quarters-earth pits for ammunition-men lived in Bois L'Etang.

Dh."lion of Fire. Aboul SOde... ea BOuthof ea'l.

Communication. Fielrf road-third class.Counle•.l.auery. Ilea., .ene.al ,,~unle•.Laucry in a.ca of Elan. Lo nailly-

nothing on battery itself.

xA.I.S. Coordinates •••••••••••••••••••••••••••• 355 520

Surveyed Coordinates, G.2-C (see remarks) •••• 355 550

Mean S.R. Coordinate J55 610

Y

.236 020

236 060

236 085

.l.




Remarks. This area in and near the Etang Le Bailly had excellent defiladeand. easy communication to the vicinity of Nonsard-it was used very ex-tensIvely for transient occupation-the S.R. forward observers invariablyreported the bulk of new fire during raids to come from this area-therewhere ten emplacements on the peninsula by the farmhouse-No.1 (west ofouse), and No.2 (in ruin of house) had been used by 77's, but not this

year-No.3 lay against the east wall of the house, and No.4 was about 25paces east of it-Nos. 5 and 6 lay to either side of the line of the damextended-No. 7 lay by itself, 100 meters farther east-Nos. 8, 9 and 10Were in a row about 70 meters still further east, out in the field-Nos. 3,4~5, 6 and 7 had been very active very recently, up to or inclusive of thenIght of' the attack-they last contained 77's-these emplacements werenot all considered by the surveyors, who reported only three of them, Nos.

1, 2 and 3-the coordinates range from 355 500 to 355 800,". . '. . 236 000 236 200 the five active

Positions lay betw~e~ 355 54,0 a'nd 3'55 690. The mean center of activity

236 040 236 135 .Was 355 630-these figures are taken from the map detail checked against. 236 080 . .

the three emplacements surveyed:-the S.R. position is seen to be particu-l~rly good when the complexity of the battery positions in the area is con-sldered--;-located by S.n. 15 times, 2 Q's, 7 R's, 6 RR's-given as a 77 and10.5 firing on Rambucourt, Beaumont, Mandres, etc.-last reported August19th-l\lap squares 31 and 32. .

Battery 5561. .C l'b ,. .

1>; J re: . 77-from wads and ammunition. '.,., r,':

otectlOn. Four emplacements-heavy concrete construction-evidently old and. reconstructed-the type of emplacement favored about 19]5 to 1916-heavyConcrete structures near for men-No. 4 the most recently and extensively

D' us.ed, possibly the only one in recent use~ . :' . , .JrectlOn of Fire.-l\1id.direction east of south, perhaps 30 degrees cast ofsouth. .' ,

Communication. Ordinary road~narrow.gaug~ northwest of pond;C ."Ounter-battery. Very heavy emplacements practically destroyed, but in use upto very recently."

x y~.I.S. Coordinates .. : .'., 355 '500 . 2.16 140

11 IITveyedCoordinatefl, G-2-C (center of '4) •••••• 355 520 236 145

j~Ienn S,R. Coordinates '. 355 5~0 236 170

nem~rks. Located by S.R. 20 times-3 Q's, 11 R's, 6 RR's-last reported June,11th as a 77 firing on Seichcprey, Hambucourt, etc.-Map squares 31

nnd 32.

, Battery 5763 (or 58(3)

,Calibre. Anti.aircraft 77 co~bincd with transient 10.5 in same edge of woo~s-four circular, concrete piers found for anti.aircraft-numerous wads 10

1> west corner of woods evidence a 10.5Howitzer.' , :.roteetion. 'The anti-aircrafts on concrete' piers 88 above lltated-NOs. 1 and

built into old gun positions near west corner of wood-living quarters

C' 10 'WoQds. .

Ounter.huttery. None on' posit ion...

"

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' ' '

" " '

'

' " ~

" '



j


sqlJlIre 3.1.

x yA.loS. Coordinates as a 10.5 .•••••..•....••.. ; .. 355 660 236 :~60 <I

Surveyed Coordinates, C.2.C, A.A. Position .•••• 35S 72S 236 230.

Mean Sound R. Coordinates, for 10.5 .•••••••.•• 355 696 236 296

Coordinates, (rom Map Detail ••••••••••••.•••• 355 710 236 2HO

Remarks. SoR. made 18 10cations-4 Q's, SR's, 9 RR'&-reportcd as a 10.?Howitzer or 77 with bursts on Beaumont.Bois du Jury region. The Anti'Aircraft was reported on four occasions only-the surveyors missed the ,lecond pair of anti.aircraft columns which lie at ahout 3SS 840-Map

236 280

Battery 5457

Calibre. Transient surveyed 77 position-from wads and piies of ammunition.

Protection. Open position-ground level-dead branch camouflage for pieces.Direction of Fire. About 30 degrees east of south.

Communication. lip country road alongside of hed of Etang Le Bailly.

Counter.hattery. l'ione 011 pOllition-heavy H<:cillenlalshelling ncarlty meunl fof I'S5.'")(). . .

A.I.S. Coordinate.. None. •

S.n.y.d C.. 'din.,••, G-2.C. Non.. x y

f.oordinate8 (rom ~Iap Detail •.•••••••••••••••. 355 460 235 720

Mean SoR. Coordinates 355 4.60 235 710Remark.. Batteries S556 and 5456 are made up of ten emplrtcements lying in 8

row from 3SS 455 to 355 600-these are all completely ruined from age,235 625 235 670

. and have not been used in several year&-A.I.S." however, rep~rtetlS556 as active in the 30-day list, and 5456 as active in the 60.day II1;t-during the entire period of operation S.R. reporled 5556 once (J uly

19th) and 5456 not at all. The report on 5556 was a short, rated n, onthe new position 5457-the flares from 5660 and from 5457 were doubtlessly

,,11aACribedvery naturally to 5556 or 5456, as these showed up very clearlyon the Ilhotograph.-.5157 was reported by s.n. 5 timc&-l Q, 2 n's and 2

RR's, given as a 10.5 firinlP:on Rambucourt and Beaumont, and as a 71

firing on lIamonville-board sign reading Art. Stell. 106 in position-Map-quare :1.1.

Battery 5966

An impartial consideration of batterie8 in the Cnrgantua group must include

menLionor S966-a banel)' of 1:icm. Howitzers, apparently used recently-'~thCl'le 1I0witurs WfOrenever dctected in action by s.n. or by any other

agene,.. It is tl.e only battery which was not detected in the area.

The batterie. hfOredescribed in detail are selected from this group, a8were alllOthe one. taken from the Mont See group, as typical. Comparillon ofthe relult. with thOle for the Mont See group will show the character to be the. i

lame for all. It i. not, therefore, profitable to present a more bulky or compre-

henlive report. The two groups Ilere studied are hoth from the area coveredby SoR.S. 1.

~

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o ti It ma~ in consequence be thought that the results shown represent anap mum smce the base survey was acc\lrately rechecked, the handling of theL~itr~tus and the computation were continuously under competent direction, theand erIes worked on were definitely emplaced and the results were numerousloc t~pread over a period of some six months. This is true insofar as the meanwoa IOns.are concerned. Better results cannot be expected and ones much

Thrse mIght sometimes be secured, depending on the quality of the personnel.ime accuracy of the individual locations could, however, have been considerablYte proved by the use in the calculations of a scientifically determined wind andin:rp~rature such as result from the work of so-called "wind sections." TheTh IVIduallocations do not, therefore, represent the optimum obtainable by S.R.ac e weather errors, being accidental in character, will probably not affect theCuracy of the mean locations. .

8ecrncs~lts of the character obtained by this section can be duplicated by anyof t~on SImilarly manned and similarly installed on a fixed front for the lengthby Sm

n

ehat S.R.S. No.1 was in operation. The very nrgh accuracies obtained

Dli .. 5. No. 1 down to the order of 10m. result from the averaging of deter-pon.~~Ionsover a considerable period of time. A dependable P accuracy for a'se~I IOnrequires seven to ten independent locations, that is independent in thetha:ehthat they are determined under different weather conditions. This means'fro t e battery must fire from one position for ten or more days. On a movinga ~t ~hese conditions do not obtain so that S.R. sections operating againstth OVlDgenemy cannot be expected to give mean results of the accuracy oftooLe shown in this report. The individual determinations ought, however,to Le a~ g?od as those here shown so that one rated P could be depended on

e Withm 50m. of the gun firing.

GROUP3-MORT l\IARE-EUVISIN

a This group was covered by Sound RanO'inO'Section 3. The area containssi great number of batteries, so closely spa~ed~ and so interspersed with tran,.a Cit positions, that it becomes very difficult to arrive at clean-cut. results intra yzing the sound ranging locations. made there. A few charts giving loca-Wons are appended to this report. These are sufficient to show that the resultsve~e essentially similar to those obtained by S.R.S. 1, although. because of ah~rlicty of reasons connected with operation, not on the whole of the sameIg 1 accuracy. .tl lhe section made five hundred imd forty locations distributed amongstr Ie Orty batteries shown on Map 4, attached hereto. The plates show the'

C;~lts obtained for seven batteries, F9666, G0160, G0653, G1263, G3475 andt ?60. Detailed descripfive data are included hereunder for all of these bat-

eries excepting 3475 and 3560.

C Battery F9666

pali.bre. 150 How. from gun wads.rotection. Deep emplacements of earth and stone, wood foundation. Over-

h~ad cover, camouflage, wire supporting branches. Four emplace~e!1tsWIth complete connecting trench scheme providing leads to ammumtlODtunnels and bomb.proofs. The position is in the open and on the top

D' of a steep bank.CIrection of Fire. Uncertain, roughly S.W.ODlIDunications. No particular road along positions. Extremely poor ap-

proach. Guns pulled out to rear of emplacements. Narrow-gauge R.n..

C' In draw 100 meters to rear.ounter-battery. Moderate. Most severe over No.4 emplacement.

'

' "



20f,OTE ON ACCURACY OF SOUND RANGING

x yA.I.S. Coordinates, 9666 •••••••••••• ,.",..... 359 580 236 580Surveyed Coordinates (C-2-C) •• ,'"",.,., •• 359 570 236 570Mean S.R. Coordinates ., ... , .... , ••••• ,...... 359 600 236 615

Remarks. This battery was reported by S.n. eleven times with accuracies,

4RR's, 7R's. Civen as firing on Seicheprey. Bois de Jury, Beaumont- / .Flirey road, as a howitzer calibre (?) and as a 10.5 howitzer. Last re-.ported by S.R. July 21, 1918. All emplacements have appearance o~ reocent occupancy. Gun wad appears still fresh and there is much of 1t.

Diagrams. The individual locations of this battery are. shown on mapsquare No. Cl.

Battery G0160

identified by gun wads found at three of the em.Calibre. '10.5 How.,

placements.

Protection. Four emplacements, earth covered with camouflage wire andevergreen branches. No foundation present. No dug-outs at emplace.menta but some in vicinity. Position in open on reverse gentle slope.

Direction of Fire. Uncertain. roughly S.'

Communications. Field artillery road in rear.Counter-b,lttery. Slight.

x yA.I.S. Coordinates, 0160 •• , .. , 360 130 236 020Surveyed Coordinates (G-2.C) , 360 140 236 020Mean S.n. Coordinates , ,....... 360 115 236 065

Remarks. This battery was reported by S.R. seven times with accuracies,21m's, SIrs, firing on Beaumont; calibre 77. This calibration may be cor.rfOctdue to the fact that 77 gun wads were found at the No.1 emplacement,also (rom this emplacement wheel tracks showing it to be relatively morerf"c,.nt}yactive than the others were found. Last reported August 8, 1918,by S.R. .

Diagrams. The coordinates of the individual location of this battery are shownon the map square No. C2.

Battery G0263

Calibre. 10.5 How., identified from wads; 77 gun, identified from' ammunitio~.Protection. Seven emplacements, four of which are concrete and steel, LUlltin earth bank. The remaining three are open earth emplacements undercover o( camouflajte, wire and evergreen branches. Dug-outs in the concreteemplacementa. The whole group lies in the open on a gentle, reverse slope.

Direction of Fire. About 10 degrees S.E.

Communications. Field artillery road to the rear with narrow-gauge RR.paralleling it.

Counter-battery. Entire region heavily shelled.

, x y

.\.I.S. Coordinates. 07.63 ,. 360 175 236 325.' SUrYeyedCoordinates (C.2.C) .. , ,. 360 170 236 310Mean S.R. Coordinates , ..... , , 360 200 236 335

Remark~. Thi!J battery Was reported by S.R. 17 times with accuracies, 4RR's,lIR'., 2Q's, I!:iven 88 a 77 and 10.5 howitzer, firing on Deaumont andBemecourt, lIazelle, Jury, Remieres Bois, and east of Flirey. Last reoported by S.R. on Septemher 3, 1918. No.3 of the concrete group ap-peared to be the only one of that group recently active. In earth errP

"

"




p:ace~ents there were many empty shell cases and in front, fresh wadsD' s IOwmg recent activity and 77 calibre.Ingrhams. The coordinates of the individual locations of this battery ares Ownon map square C3.

Battery G0653

~nlibre. 10.5 How.rotection. Four earth emplacements covered with camouflage. of wire andbranches. Trenches connecting emplacements, earth and rock dug-out8to the rear. Located on the front edge of a low bush area. No. 4 pit at

. top of slope.

glrection of Fire. Approximately south.Colnmunications. Two hundred meters to good road. Guns pulled out front.

,ounter.hattery. Heavy.

~.I.S. Coordinates, 0653 360x600 . 235

Y

290~trveyed Coordinates (G-2-C) ...•.• '. • • • • • •• •• 360 590 235 280

n can S.R. Coordinates .•••••.•••.••......•••• 360 550 235 330• eJnarks. This hattery was reported by S.R. eight times with accuracies of

3RR's and SR's. It was given as a 10.5 howitzer firing upon Flirey, Boisie Jury and west of Ilernecourt. It was last reported September 3, 1918.

O. 11emplacements show signs of recent construction.

lagrams. The coordinates of' the individual locations of this battery areshown on map square C4. .

x y

~.I.S. Coordinates, 1263 .•.•••••.••.••.•...•.• 361 175 236 335h~rvcyed Coordinates (G.2.C) •••..••.•••••••• 361 190 236 340nean S.n. Coordinates ••.••••.••••••••••••••• 361 22? . .236 38,0emarks. This battery was reported by S.R. 12 times With accuraCies of 9R 8

D' nnd 3RR's, given as an anti-aircraft.lngrams. The coordinates of the individual locations of this battery are'

shown on map square C5.

Battery G1263 AA~alibre. 77, identified by wads. .rotection. 'Three emplacements, very good condition, circular in form, earth

and rubble masonry; center pedestal concrete with circular scale'mountedon it, graduated from 0 to 640. Good dug-outs near position. This bat-tery lies practically in open, except for a few 8traggling trees on gentle

C reverse slope.COmmunications. Good artillery road in rear.

Ounter-hattery. Slight.

Battery 3560

~nliL~e. 77.rotection. Five concrete emplacements-roofs of concrete and iron.

Battery 3475

Calihre . 77}l' . •rOlection. Four earth emplacements-camoufJaged.

'



1


GENERAL REMARKS

The detailed examination which was made of these areas brought outcertain facts of general interest concerning the enemy's habits in handling ar-

4illery_ It seemed, for example, as if in recent months he had corne to employ

those battery positions which were subjected to our counter-battery o~ly

transiently_ He made no attempt to protect his new emplacements, prefernngto withdraw his guns after a certain period of use. To this end, the emplace-

ments were set near roads, and were so constructed that the guns could .be 'i

pulled out by horses. In cases where older concreted emplacements whIChwe ... difficult of e ...... exi~led on the .ite, these were ahandoned, an~ new ope~ones, Without any protectIOn, were constructed in front of, or besIde the 01

ones. Batteries FOC).17,F54S7 and G0263 are excellent examples of this prae-tise. All the heavily concreted emplacements were old, probably of date 4

1915-1916, and, without exception, abandoned for open emplacements nearby •.TIle effects of 2.1 em., or even 15.5 cm. fire on the concreted emplaceme~ts j

were very destructive in case hits with delayed action were made close besIde,

th.em, b~t .no~ otherwise. Some heavy counter-battery work was car!ie? out

Without lDJurmg the emplacements fired at seriou.s ly. The great maJonty ofthese hauerie. were located in the forward ed ... of wood •.

In addition to these emplacements which apparently were permanentlyoccupied, unless fired Upon, there were many surveyed transient positi?nsstaled out and marled "surveyed" which differed from the others in no~ havmgwooden gun platforms, and in bein~ without any housing accommodatIOns fo.rgun crew&-e.g., F5-1S7 (new), F5369 and G1465. These positions were eVI-dently repeatedly occupied.

There were also numerous unsurveyed transient positions, douhtlessly, usedduring raids. .The fields near the Etang Ie Bailly and also those in the neigh-

borhood of GI465 contained evidence of the general use of artillery in all parts.

Finally, positions were taken up almost any place where there was suitabledefilade on the extensive narrow-gauge railway system which served all partsof tile area_ ,

The enemy, maldn,; use or his railways through Thiaucourt, could ~asilyget an enormous weight of artillery into action on very short notice :WItho~tany larg~ amount of preliminary work in preparing emplacements. IlIs. ~~1D

attempt 10 ft>cent months was unquestionably to obtain mohility and fleXibIlIty .of artillery dis,P?sition rather than to attempt to protect his pieces in known,permanent POSItIons.

Non I Th. cUla ,1.'1'11 In the thrf'1l .roupi covered b, thll report were coll"cted aDd-pllN! b, Capt. C. B. BaDonl. Enrn. U.S.A., who w .. In chargll or the louDd ranging eee-llODI durin, their operation OD the front. The p1atel were prepared under hil direction. HeIe thorouaM, flmlliar -hh th. antecedentl of an the dllta prelented. and II

U

lirunteel their1 , ud .....,.1 aecarae,.

I'

i

__ '



,""';...•.

Z"',",,:s_1-----------------LEGEND

Mea" S.R. Location

A.I.oS,

~rve~ed

IV1AP saUAR~ l.

2..:53.5 ........;,s::o---------~--------------J351

ENCRAVED AND PRINTItD AT THE .ASIt PRINTING PLANT. 29TH ENGINEERS. V ••• AJIIIT

'



MAP .5QUARE. 2..

8-

D-O

Q 0

R •

RR x

LEGEND

Mean SR. LocoTionA.I.5. ..Surveyed

Individual 5.Ft.

.351

t;NI.RWED AND .. R INTED AT TilE .,~It'Rll'itlJ\1. ..LANT. 29TH t;NGIJ\EItU, lJ••• ,UMY

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MAP .5GUAR E: ~.

8o+-tC'r!:l z'9SS.

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A.:E.5.

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ENCR~VJU) AND PRINTED AT TItE aUE PRINTl!'!G PUNT. 29T1I ENCI!'!U." V••• .tallY

~~2.5-:---------------------.3-5~~.



MAP SQUARE:. 4.

x x

•

lC

LEGEND

II

~.I\.Loco'tio..,.

p

Q

R

f\R

M~Qr\ S.R.L.ocoi'lon

A.I.S.

IINGRAVED AND PRINTED AT THII BA811 PRINTINC PUNT, 29TH IIICCIICi:IU'I, V ••• AR.,Y



MAP 5QUARE 9

Ba1"tery 08 ~6

LEGEND

Mean 5. R. Location

Surveyed It

~~"S0.--;:;s;-----------------------J 351.S

ENGRAVED AND PRINTED AT THE RASE PRINTING PUNT, 29TH ENGINURS, v••• ARIIY



MAP 5QUARE '0

ENCRAVED AND PRINTED AT THE BAU PRINTINC PLANT, 29TH INCINIJ;". V••• ARliT

LEGEND

Mean S.R.. Loca1"ion

A.I.S.

IIII,, J5"05I .I

I

Ba-ttery 0836

5urve~ed

Individual

"

5.R. R.Q.

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MAP -5QlJARE: U

Batte ....y ... }O~47 /

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M<Za~ 5. R.loca+ion

A.I.5 .

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MAP SQUARt '2

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IlNGRAVED AND PRINTED AT THIl BA81l PRINTING PUNT. 29TH IlNGINIlEIlI. U••• AR"1'

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LEGe.ND

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5lJr-'~eytZ.d' .. a4I,.,divi dUQ1.).~:.p.... •Q" 0

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MAP -5QlJA~E G

LE.G~Nt:)

Mean 5. S;? Loc:.a4ionAA.I.5. 19

5~rveyed e-o

.J5Z

ENCRAVED AND PRINTED AT THE BASB PRINTINC PLlI'fT. 29TH BNCINlI :J :Rt. V. t. "111fT



MAP .sQUARE. e.

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MeQn 5.R.LOCQ"tion

A.I.S. It

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EI'IGRAVltD AND PRINTED AT THE BUE PBII'ITII'II; PLANT, 29T8 EI'II;II'1EERI, U. t . . . liT



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MAP SQUARE 7.

LEGEND

Mean 5.R.Loca~ionA r.=>.

Surveyedlhdiv iduol 5.R. Q

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ENGRAVED AND PRINTED AT THE .ASE PRINTING PUNT. 29TH RNGINEER8, U. '0 ARliT



MAP ..5QUARE. '4

Batta.ry ZG48

M eon .5. r<'. Loc.o+ ionA.r.~. II rI

5u",v~jec( " a-c

Jnd; vidual S.R.~ t •

Q It 0r;? II •

(? fi7 tt J(

IlN(;RAVED AND PRINTE:O AT THII RASII PRINTINC PUNT. 29TH IlNCINIlIlR •• V ••• "RIIT

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I

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MAP~QUARE:. 15

.?battery ZG48

LE:Gf:ND

Mean 5. R. Loc.af'on &

A.I.5. II

Surveyed .. [;)-Q

ENCRAVED AND PRINTED AT THB .ASIl PRINTING PUNT, 29TH BNGINEE •• , U ••• A.IIT



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MAP 5Q'-'ARE: IG

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A.I.S. S

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ENGRAVED AND PRINTED AT THE BASE PRINTING PLANT, 29TH ENGINEUI, V ••• ARliT

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MAP ..5QL>A~E: 17

BaHery leGI

Mean 5. R'. Loc:.ahon A

A.1.5. 18 1

.5,",rve-)'ed'-5.rH~s') Loc.Q~ion e-eIndividual 5.f? "pt. . II •

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ENGRAVED AND I'RINU:D AT THE BASE PRINTING PLANT. 29TH ENGINEERS, U. S. ARMY

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j



23".5350 ~5'

234.5

o

x

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(Ie L.oec'tiOr\5)

L.EGf':ND

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ENGRAVED AND PRINTED AT TUE BASE PBINTINC PUIlT, 29TH EIlCIIlIE", t l .•• .lB."

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354

MAP .sQUARE 23

"

LEGEND

.5 R.LoCQf"io,.,s

P

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f\l!e-o", .5.R.L.co~jo'"

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ENGRAVED AND PRINTED AT TilE BUE I'RINTINC PLANT, 29TH Ill'lCIl'lU." u. B. AJlIIY



MAP ~QUARf:24

!LEGE.ND

MQGP'\ S.R.LocG+ion

A.I.5.

ENGRAVED AND PRINTED AT THE BUK PRINTING PUNT, 291'8 KNGfl(&PI, V. I. ,..IIT



II,

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MAP SQUARE 25

Ll:GI:.ND.

"1ltQn ~,I<? Loco "ion A

A,I.~. ., C!:I

, urvq,yed •• !:HI

ndividvoloS.R,"p'.. •Q" 0

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EN(;RA\'ED AND PRINTED AT THE BUE FRINTINC FLANT. 29TH &NGINEEU. 11•• , ARliT

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MAP SQUARE 26

LE.GEN~

Mean 5.12. Loc:.ot,c»r"\ A

A. \.~. C8I

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~Q+tel""y

34G8

354

ENGRAVED AND PRINTED AT THE BASE paiNTING PI.ANT. 29TH .:CGII",.a!, V ••• ARMY



LE=G£;NC>

Mean .5. R. Loea+,onA."S, ..

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Indivia~15.I?~P' ,Q 0

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MAP SQUARE 27o

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(j6

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I

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E!'IGRAVED AND PRINTED AT THE BUE PRI!'ITllfC PUI'fT, 29TH ElfCI!'IEUI, 'D••• AallY

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I

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ENGRAVKD AND PRINTIW AT THE BASE PRINTING PLANT. 29TH ItNGIN£ERI. U ••• ARMT

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MAP SQUARE 28M LE.GE.N~

~al"\ .5. Q. Loc:.a+ioro

ct A.I.5.vvryeyed It

rndividval 5.rz:P" of

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MAP SQUARE 29

•

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MAP SQUARE 30

Batt~('J. T.53GB

L.CZgenCA

M~an .5.R.Loc.a+ion A

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I

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II

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II

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MAP 5QUA~f. 31

e>a++er"y f ~3<Oe.;,

L~GE.H~

Mean 5.1<". L.ocGlt"ion &

A.l.S. Of C

51o.,n-.veya,d a-e

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EreCRAVEDAreD PRINTED "T THa B".a PBlreTlre" pureT. 29TH areClreaut, u.•. "allY

~



I

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MAP SQUARE 31

Battery

F ~SGO

Lq.j cz,.,d

Mean S. R. Loc.ation 8A.I..5. .. f2

..5..,,..v~yet.d(5. (?MdfJ') II

l"c/i\l,dual .5. f?~P.. ".Q. .. (j)

R. .x

356

[

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II'I

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MAP -SQUARE: 32

LE:GENC>

MQ..on 5. R.\...oc.atiol"1 I!i

A.I.5. 1m..svrvczyed r:HI

356

I

II

I..A.

ENGRAVED "ND PRINTED AT TSE BUE PRllfTINC PUlfT, 29Ts ElfCIlUUl, u. I. ARliT



MAP .5QUAR£.

X

Battery f 5763

LEGEND

~~I.~..R. Locc:t1on.sU"ve~ed ..J:"divldual SR. "Q-

"R""I'. R"

x

6a"ttery 5457

II

III.....

ENI;KAVED AND PRINTED AT THE BASS PRINTINC PLANT, 29TH ENCINEER., U •••• RIlIY



I,...i

MAP SQUARE C 1

LE:G~Nt)

Mean 5.12. L.oc:.a.Hon AA.'.S. •• I!J

5urveye e:t It o-c

\ndividvQl 5.~;p.' •Q 0

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.!J~O

IlNCRAVED AND PRINTED AT TRII IASII PIlJl' ITINC PLANT, 29TH IlNCINIlItBS, 11. So AIlIlT

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R

RR

MAP SQUARE C 2

Battery 0160

LEGEND

MeQI"\ S.R. LocQTionA.I.5..svrV€!:Jed

Ihdiv;oual .5.R.

~60.5

IlNGRAVKD AND PRINTIlD AT TBIl .A8& PRINTING PUNT, 29TB ENGINEERS, U••• A.II1'



MAP SQUARE C 3

LE:GEN~

M~" 5. s;? Loc.o tion AA.loS. Ci:I

5ur'"veyed ...,. [J-{J

Individ"'ol S.Ii?P. •Q (i)

.?1'? •• J(

360.5

ENGRAVED AND PRINTED AT THII: lUll: PIINTINC PUNT. 29TH II:NCINII:Ue, U. I. ARIIY

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MAP SQUARE

Bo"t1"ery 0653

L.EGENDMean .5.R. LocaTionA.I.~.~vrvQyed .,

IndiVidual S.R. R

RR

A

I8J

e-e

•X.

361

a1'lCBAVaD A1'lD PRllnaD A'I THa BASa PR '1'lTI1'lC PLAin, 29Ts a1'lCI1'laaR', u ••• AJlIIT



5G1"ttery 1263

LEGENDMecm S.R.. Loca'tlon

A.I.~~urve~ed

Ihdividual 5.R. R.

RR

MAP SQUARE C5

-'62

ENGRAVED AND PRINTED 41' THE BUE PRINTINC PLANT, 29TH ENGINtEBS. V••• ARliT



LE.6ENDMean SR. LocaTionA.I.S.

Surveyed

!"'aividuQ' ~.R Q.f\.

R.R

6atter~ "560

ENGRAVED AND PRINTED AT THII BASil PRINTING PLUlT, 29TH IlNGINIlERI, U. '0 ARIIY



lfGtNl)

Mean .s. R . L._c:.a"',cu., A

A.I.S. III5u~veyedIndivicl&JQI.5.k'."'P' •

Q .. 0

R II •

RI? II )C

f>a+.J.ery 3475

ItNGRAVED AND PRINTItD AT TBIt BASIt PRINTING PUNT, 29TH ItNGINIlIlBl. V ••• ARMY

~

Documents

Notes on the Accuracy of Sound Ranging Locations