---

84 REF ID: A65651. 

Office Mcmo/lndum • uN1TBn sTATBs GOVERNMENT 

TO Mr. Friedman DATB: 7 August 1953 

PB.OM I 

SUBJECl": \. ~ 

The attached paper is the one pr.epared by LCDR P.J. KARL for use with \:( \ 

the "Subnarine Chart". For your retention. ~ ~ 

..,,., I\ 

('> r ~t VR 7 ~. ce".~ 

~· lo -A. }.Sil / ~ 1>~ ~ c;;r~ 

v 

Declassified and approved for release by NSA on 08-22-2013 pursuantto E .0. 1352a 
.; . .. 

/ 

.. ~ . I 

' .. ' • 

REF ID: A65651 -. _ · ;·· . 

. ' ,_- .. .J.,i.. ·~··JJU'..tl ;, • . e~J\~("f: •. ."\ ·••! f rti.1'¥?.iac.·~ a}\ . . 

P.CM!Hl'.:! 1.QS;~ f.JF BnltJ'.'Jf,. .U:LIEn Al.n ~-umL 

~-nl'.'>~·1110 BY U/S A~~tt :-N II ·;;r.mtrr "*E. n• 

. ·. 

- . 

TM c.bart eatl\194 "HOntb17 li0asee ot ShJ.P.Ping b7 U/6 Action" 

lll•tnt&s the rdat.1oub1p bctwftn ·!he Allied *1agglt; ag&!nst th• 

r.-einan ti-l:D~~t. mera.aee ·Sn ~orld ittu- It and tM •~billty ot accurate 

iil1:i ts.17 opcrat4oaai intelligence aeriwd J)"Oa CJ!7ptallal;p1s {l.e.1 

Nacune. tlK' text.a of,.,.., Jl'&d1o *'8.;;a,..ea). It~- takea into accomrt 

tlw ot.b.er' p-rine!pal .factiors 1'11e~ _ 'inllaen~ tha Out.co. ot tbe At3.anU.C 

batQ.e. 

A fd.f.01t1ca0 t.. ·t.wo-fold c~i.Aan ot thG Valutt 0£ t::a1:.witCation 

Intali;_~encc (~;.tmrr) Ja aar~ t• a~t f1"om ~ ~alS"si• ot Qe 

c:Mrt~ {)&"!he= one; bad, it la -1.~bl~ cl~ar that. lritia - ti.!. 

COOW contributed -directJ.7 Md aabatanUAU7 to t.h• Allied Y.lctol'J' 

oYer the ~eman V-boat. ·CD tbc o·tber haiad1 tile atageerinf, louea in• 

. ' 

tl:leW.. m .:'l.lied tdJSpp1'rf' b7 ti-boats• r,.. ._ ~uibrtak of the ar 

uratll th& •~ of 19L.J •. wr. cloeely :r.lated t.o the ~ of •uccachieftd b.Y th~ :WJr.ati C<Jttlf orran:Uat:ton (tbe •1• .~)against. 

}.Uied .-~liov.·t.1ona. 

fbl"ae d8rroee ot .Celfnrt •-=- are npl'Umted an the d1art. tar 

hotb"Br1'11b • t::.~:. and t~ nd1o l"ltc:lll~i..10• {R.l.), nacalJ lov~ · 

~ • .Gd. hl.:;,h ~b1lit.7. GCX'Jl&Jl -.ic»i..l.QU (.6iween li."bl. 

teadQll&l"ten ~nd the tl-IJM.i.. Q..eet. ,.... carried ~clunvelj· 1.."l tbe ~ 

· llllCh~ oipha (!.:1:~..1)1 • blgla-gr~ .,.tea. ID oonsequencei the 

cantJ.ned Dl'lUIZI - i,!.:·-. Cl"JP-a.mal.Jt~ at'Wolr. vaa conctntnted on thi8 ., 

: ' 
. -:: ...... 

-· 

\ 

•, 

REF ID:A65651 

Gt. •luticm but. ala> ~ ti. l1lld. tau.or. J'or iaedlate operational. 

.tfecUT...-a of· t!le · uiton&Uon. LOlf readabllit)', Ui....Cor•, 1nd1c&W. •• • •i 

a low "tate of 40.luttoii lrltll a t:lae. 1oC ih ~t.inl Ule uasaga #tlOh · 

that Ulc 1n:toraat.1o!J ob~inecl 1s ~r 1IO uta 1W. ••1dtate ope8tSonal 

ettect11'mw. It i• •dul.1 bo-.r:. tor bulldinc .a bukt,rowMI or 

at.i-ategic taf'oNa.tlon.. Jtedl• f'eadilbUtt71ndlcatea app:roxD&telJ' a 

~ 10l~ ol tale •-1•1 __,. -or vhlch can be ~ :la a1Jffiaim'4 

-t.ime to lie or 1-.d1Ate tactical •lue. 1111h ftadii'.:>U1t1 indioetw 

\bat; .i.1 O~ :rroa-t al' the Wl@'d C&:fl be deci"JPtecl COllp~ (•.aolidl.J•) 

aD4 can be niad curnnU7 a1d cont..m•Ul,. '4th a .t.-a of ~. . . 

-~ ta ~* '81'1\i.ti - ·u.s. e.,P~1o ettort. -. 41.ftCted 

~""lW:st the ~t: el~ .Mdd.ntt, the r;&JMD .as• ~ aoncct.ntect 

en cod£• -4 oipb.cra COBtaiJdng int~tion ngar41ng Allf.ed. COftftJS ClCl · 

aerdlant abiWinc• · 'Bo ~ . ojJ- •cldne 

. 

vaa. aYall.atile ~or ~ 

uat: tor tM9 tntno -.,w. l•te in 19U• BIDOe, ~.1914 •tll late . . . . 

l.9LJ., all oL tU W*ed coim>1 ancl ilhip;:inr; toromau.on .. 0'~1e41n 

leas llEC\ll'e cOIMs ad dph••• •4 1fF .. ag&lnat. ..._ iha~ tile •p . .· 

. . ~· law l'tM9bU~t7 ot JJ.lted tnf'tk• it. &e1na tbat. J.n't6Jl1,_.. 

1111a obta1ned troa ,.dlng loV gade apt-. such .aa Ml"llbla\ lb2p .._ 

UU1 aircr.Z:~ ~~- OOdea. Medi.Um f'M4ab~\)" _ims.catee part.1al 

\. '\ ••.lrable, wu ·not ot th• esaence 1n 4ec17P\fn(; tld.a tiiat.t'ic1 roi- Uae 

\. . . . . . \•a• SC91.ce. at.re9$ed Ute illportance ot lrai.1.dme; • a ba~ltgrocd. ot 

\ . 

\ 

\ 

I 

~ 

: 
REF ID:A65651 

OOllft7 ~-· and d•el~p; ·~- patterna. 1'0~ th~ 

P11'POM• D:.-em •t dcl"Jpte were ob1'1o•l1' of peat 'ftl••. ta . . . 

p81"1oda . 1118n a•c.U.w . conaja 

. .._.. . 

.snr. approx.l#te1!1 t.be ~ 

~. put· -~de* of ~J' babite ad procedm'ees togetbe vS.vi 

Ula tmo111rqullrit7 of.~ ootM.7 ..U1nc patrtm'ml, _. •de to coa--

penaata ror \Ila laek of currat 1af«tmaiion on Sndl'fidml camo,9. 111ib 

_readabUJ.t.7 iatllea.tes complete •lut.ion ot the '8r1Uah • t.~. high gn4e 

la.ftl.· CJpb(J' --Tabl•• ... •d ~8-~ and decrJ.ption ot the. ... eagee 

on _a cunent &n4 contia110u baau. !be •p t)enioa .·ICllieY-1 f;bis detr..i -

0£ auDCess onl.7 aee during the ar • boa Jullll"J' mtll ju-. ot 19hl. 

la addition. "'° . .in'k1l..igece •1"4 .rr. ~t.anaJ.,..i.., the c... . . 

b!ne4 Britillh -: v.s. etton ~ ••~• tm othaz- 80\U"Ce. of infbratton 

. . 

baaed upon. the c.eimns• he&'f1 radio v.rn.o •. The• we:te Ulreetion 

Fin4Ung (D/P) ao.d \nn~t.ter i~t.iaft (TllA am Rl'P)1' P/1. ;ta a 

. utMct ot locat!ag a U-amad.$\er b7 ol»tta\ninc •iaul.t.aeoua baring• ·~ 

aeYln1. receiftnc at.a'U.ona and plotting t.ha ara ot· irrtenection oZ the 

bearine Unea. na. s.• a llCtbod of 1den\1t71ng ~ radio !I!!'! .. b7 hi• 

&ending ~ctertattca1 while it_11p 1• a •ti'iod ot ~JJ.ne; the nd1o . . . 

~\Ung atatloa br -~ '!Je et.C.trical cflai.ac~Uca at th8 

tra.ud.•aim. Drth tth a8ct tr...S.tter tdlllt!ftcatlon·proeedures 1"lZ"e 

1ll8d ~~veJ.7 •4 etreetlftly apmn \he 11-boa~· Intelli.gcce ta., 

.:ctn.CT •4 .applica\lon We ~ llOrO l:f.:m1 ~ tban in t.he case o.t 

1DMllig9nce deri'ftlel fraa CrfPtanal.J11U•. 0 

., ,.. 
lIBF ··In: A65651 

'· " 0 0 '· I ~ ! ~ ~=CSJ~.,'f:~ ~ 8 aetc t1nausn Ii ........ 

. . 

7"11. the oat.m.t of '1U". \Wltil · Avewt of 191.o •. Ula c...-.. .enjoJM \. 

·' 

a per.iod of _.. • .Nadabil1 t7 e· IJl'1U• COdea &l'Ml o"Spb.trra. (Thia . . . . ' . 

. : tacw ·11 ~~w l>y ~ ere• plai4 ool\ID t.a.rd the left Mml 

a1411 of tile chart..) ·. l t. 11 lfno~, tea .;..pi.,· -~ 'bot.b Bl'i\1* lnal. . . . . . 

~ !foe 2 Ud 11'&-1. - CJP~ ~ lbe f& WON 

- approslaa'917 . SOf. . 

~I . . . 

~ ~ IPnDg 4nd -er of ~~ ,..r ~ t!ae lac of.~ 2b houn 

·~ qt;dw camon. ~ua. wluabl.e WOrMtioll en the dSArpoa1tian o~ tbe. . . 

. ldUSb f1N\ wa &nu.a~ 1'le •oellmce ·of ttae· ~ .. ·~c• ·in tb. 

lat.tar part, ot thU period i• hf.1#'-lighW by tw aucceaatal a.-n ' o - "I • - . . 

atacb on laTal. ~orces • the ~ of Jf .. LS. OIJP.IOt£ an 8 ,_ . . . 

and a. 1 ... tpe8koular lMlo&\. opea\jon •r.Un•~ tile Woftbera Pau.l 

..... ia .. .

f'.)Qr.lq ..._ :fka\ DSm .-ita. tollllllring the o~ ot _..., \lie . . . 

. • .....,.. of U-bo&t• .antlabl• tor op....Uclia ·qamn abippills -. ..U, . . . . . . 

_. ~ l~. et Al11-.t .,...eel• wr-e nl&tt.:'lltl.7 Ugbt. (lSO,aoo 

..-:. waa in U&e '-Y1••' --•>• · lllwftr•. ill Jla6 Ul&O,. afkr' re- . . . 

i .... ot ~ 11-ba&'11 :rr. tbtl 11wnglan ....,.ifp, elnklag• ~ 

·. st~ au.1 tMJ" naolle4 JSt>.ooo &SW ton• bl Octob9r of U.tr - . . 

79U'• 

. CJlanc• 1n~ .. tnv nntbb kwl code ua CJpher u A~ 19'&0 

ns1i1Md ·!.JI • omapletel.7 •evcc~.a.. -th tor ~ ~.-n COP.JI! etf'o.r'\. . 

Sf.nkinOI coninet ~baW, 11owfU., lllnc• tia. v-boat. •re bJ' MW 

Oi*'8t.bsg oat of El'eDah )ION Sn tM 8li1 o£ Jl•oa7. H1ght a•t.aota on 

._.,. bJ aeta.ced u-bo&-te accom't•4 tw a.av 1"••• .It. -.. •'1148\ 

.. , • ..,1w tbit 1oe8 ..t satentr_ ,,_ mmtt iolll'C8, tiloro.P 

knH'ledc• ot Allied COM'07 ~' palt.e.naa ot .-.u... M4 pl"Oblble 
-~"* -bled ...... v-i.o&t. eoaa'nden 1;o cf)cttn• tl&eil' ra11• until 

--- canft Wot. 1aM ll'ldlll coclea and eiphen &pin t.ba ~~ -f.b. ~~, ...... tblS uM was OD Jo• 1ew91 cl,pto~ . 

<- bill'ftd gJ"Mft co.llm) 04, a a nnnqwrace. th.- ~t-7 of oenia 

intel.J.iglllce tiec.a -to atwiorate. Even Vl1a 1•...,.dlt succeu •• 

811ort U.""4 for cbaru ~d Sato Briu.Ja Olpha ~-

ill s.teilber beg~. t.o. haft thtdr- ett~t e1 aotbaa drought m ·Cel'mn . . . . - .. .. . . 

cxr.117 coatributed .- u appl'fjdabl.• ram.u.ri .1n Ulied std.pp!n8 i--.. 

the a~ of ~ am bJ' .ll11ect -.tion vu Jlelliribl• d1ll"1Dg 

the £int. ,.ar ad: a Ml.t ~ ~ ~. (See Iba~ greea U'8& Oil ~-. 

~eft aide of cblrt.._ ). .&111~ intelll_gmce ·and an"1"'8dllm'Uie opwatien1 

-· were not 19\ II' ~ th• t.uk o~- _COllbatting ihl• mder_. ..... 

·ID 7ebruar7 19bl,. \Ila a.... once mon began r"8.cung lov lwel ' . 

Allitd. qn.a and .aiain th• rate ot Bh1pp1ne lo•- ~-· to ll0'1lt. • I ' • 

!he u-bo&t• _....d ~ of laO°v ad launcllM «*••\rated nigh\ a~tacb 

on Cetn'°18) the" liot;lth ot APrll aav t.he til'at. da)'ligbt at~ on. & 

eonw7 by a ~boa~ group. ft• camp&1gn Sa the- open _.lt.lant1c ·~ now in 

hll ... ,._. 1be avallabillty again o~ •te.lliaence_. a:plo1tM with ~.N 

......-i• •tto•, rea111.ted in a .-rke.d :lncnue in a... ·~ 

.......... 

It. vu fn Jlaldl of 19L1 that Brit.Uh UJPt.amal,ats tint t.Mted 

•uco•.S apsnm; the a... III~ It, ... a. \rictl• at f'ir.et., •••17 

ot 1"" Na.labllit7 and OOB-ald'ftnt, but .it 80Clll pl'eg.rttaed into Md.t• 

nadabil ltJ' WS.tll aol'ter t.1Jae lac,, then l'ritbh dMrJpt.ion. in ...i .. - . 

begar.l (see red colwm.). · With--.tbe intelligence now ·a.Uab1.e to ~ 

..__ ... -s-

.,,.,,, ~lr.lfff 
e. R,EF ID~A65651 ~ 

. . --:~,·.i~U!. li&UBIH tie~~~·m~ 

1r1ua .trOlft cau:w, -the ~Ja were able :to adopt eTUiYe_ ~ing ... 

tact.le•,, and this factor$ together witb the proYilll on ot escoJ'U md 

aircraft, ba•ed OD Icel.anflt. ca1lllltd drutlc rehoUon in thipp~ lo.-

I.or te aontm. 

lr.ltiah CCE!ft -. tJOW m a peri-od or high readabllit7, and ~ 

ci7,pt1o.~ or th• ae..Mn u.._.t 11e1aa&ia •• ·placed on a cV'ft1l't 

. . . operat.tanal ~in AugllSt 19Ll. •. ~ _&aptaber,, ~ Bl"itUh ~ ... eel 

to enciphe the iridicator• for th&Sr 01m lfaYal eoctn .and cii:her• and 

t.he c..u ven qui.ck to epot. ·tMa weabllas. ~_..,, an illtereating 

•1t.mtion d'"velopedJ deap1~ tbia: na· ~ ccamn wccua, tmrr. 

vu A\o *P1'.•1able· improY~ 11l ttud.r eper&t.ional. ai"tuat.itm at, --. 

- - - -

A batU. of' t.h• cel1D: aet'Yioea d8'ftl,oped, tll.t.h the Br1tie~1 no• holding 

tile 1ll'iPW hand. · HOreowr, in. ~, a we MOtlh ecabS.necl Br:l:\llb • n.s. 

'CJpber to.r con_,. ~ introduced and the ett~~iwnesa or the V•boata 

vaa ·turui.r nduc8cL Allied -aJdPJ>:Sng 10.._ _.,.. cut. to ad~ 7S#OOO 

tons the Sollo'ld.ng 'llC'mth, aa against. :a lea• ot 10 u-t»&ts. W.Ull tbe 

failure ~ their pai.J.oi lin••~ _the ~ begiA now to aupect Britiab 

. . - ~· 

the Cel'IJ8l!Sa But tlle Collblned Baftl CJp.b.ef' IO. ) beoaM re&dabl• ~ 

. , 

~and •• ~d ~at •Urel.7 and eun•tl.7 -until Jlme. l1hta 

1i va~ .replaced bf laftl. CJphw ~. s. n-m aa oper.at.ional pomf. ot '• 

"fl• V1e aplo1ta~ion o! CJpher Jfo. S vas parM.ps tbe cr•te.~ add.a.._ 

•nt of -. Oel'llan ClJml-1 ""1ce. u-hoa\ coma~• now had tJa4t Gnl 

. . . '-'rr'?'i1. -· - ' ~ 

.. . . . . . 
• 

~--- •L'~·."-

mdleptrdabl• ..... ot locat.:tq Allied CO!l111Jla 1n ~ 11l•. 

0erun NCGaD&ill&ID.ce probla •• solYed -·on paper- at1d U•bDat 

sinn,tb- could be cgnce11tn:t.ed a~ ~·· richt. place encl at the .right . . . . .. · - . :. . . . . . . . 

'-• the V-boata wowct in.tor hea~ attack•· in &iWtJ.ant.k ·~ ·. 

along tile .. tern ~dot the O.Z.; ~e.m Allied 1..-.. 

b8aa to eoc-·(the ••rl now mova -~ a.r• breakdr::n1n for loa.a · 

a\tr11Nted to .a_.... D-boat- ac~ion. and the ba'ri.eat coacentrat.1Gt 

appears in tbe AUanU.o 0o,.-, shOm i:ft bl.act). 

It vaa dlll'ilJc tbia ..... pedod tJ!aat t.he Gel'llalUi ·added a f'o\11'\h · 

tlbeel ·to ~-uantU. -Ohine. renltinz s.a • ~l(;:te bl&ckout tor · 

!1'1.Ulh er,ptanalJ8ia• ~· bl-ed Pfi~ lasted ttJr ten cansecut.iw 

IHll'ltbs. Dl• a ...... con Unued reading Jlritlab tral!ic 'libl'o111Jaom. . . 

thl• period and the U-braa\a enjo,.d their tratea\. nee• .. •• naehing . . . . 

a peat .or· ... TSO,~ CrH• ttJna ot ah.fppSng iii lloYaber 19S2. or 

vbicll 6251000 toaa vere 1n ~ At.J.antlo. s.e sp~ J.'eliei wu 

· ·apcrie~~ bT t.ae introdtadion ot u.;-. count.c.uw .. &lJd bJ' tbe 

et£ec\1T~ua of u.a. ~ convo;;-., but• ta 1enenl-. th• V-~ta 

·eon\:1.11-4 to -.1nt.dn thf •dvantate. 1'\£1 V-b:lat oUWt._ was extended. . . -

Sato tile Qulf or lln:l.co and tile C&rib~ ad Al.11cd loaa• continued ' I • •, 1 

.. , • b!P· Unl~ 

. ~~or J>eember 1"'2 arariced ·a tvniftg: point in ~battle 

. et .a. •tlantie. Allied :i. ... ~ ~ed. to 011_• half the total or t.u 

. ·. preriowa r.on\he Rougb wau.z. •• andoubWJ.7 a factor. bu\ \ha 

taiiroUCtioll. of new eoabi.Md cipher procedm'ta oaued another blind 
• ' • .1 . ' 

. . :'~ . . ·~ 

' ' 

! ' 

.. ' 

' . ' •, I I 

" 
It .... in *1' or •a.l: that tM ~1t7 ot tho c0mld•4 c,ppher ·. ·: 

as pl'OYltd ~ r......i O.t 4Ued C"'1H n.ec•, .d. ~ea ~· . 

tnV'otimed ih• tollonne .c.i.a (.nme 19JU}. MU. - v.~. laYal. 

ClPh• 1o. s .reP1aaa CJpb8r- wo. 3,.· •od· 111 ...... ._. 1.1ae ·r._..... • • • I : II • .• o 

lost tb.elr ~f during U.. aeatla of .J-. ....,..... thQ wre- abl.•. : .. 

to nauae a per.lod ot. 1• 1'8ldabll1tfy on .lllW .• ,..._ 1n-1t47. JJ" . 

etald.rling ·rnvl\a i'roa low-l..,.;1. • •ith .Sntonat~ ~•cl~ .. · ._ ·: 

-. tnt:!ic aaal.Jala, th. o..-..a were able to r•"t ~ ~ ot th• 

: Cpel'&imal ~ud for ~ wt ~our 11011U..., Bat, U. .,. Senie•. 1-t. 

all nadabW.t7 !n tile 1'ollcndng ~TE:Jlber and a c.p1ek drougb.~ ta 

ccm.1x cont.in-4 tor, ... matiml ot Vie w.r. ·. . · · 

During ~· .... period, tM t-.po of" t.be Allied ottelliw ·tn.~eda 

on ~ aea· u ~ u ~- tAe COM!lf dlaabera • .- A eomb1iied 8Ul'face and. 

. . - . 

. all' o.f'tms1• ia .. t.he 13BJ' ot ~ area tofted a general ld. t.bdraal. or . . . . - . 

tile V-boata 1n tnor of lea daneexova ~. ft• ~oea or· ao. mny 11'-boau 

in tbe sin1clng 0£ ao tn n.lied ••als waa becOJdng a ..,..,.. expemift 

piece ot ~-for the oeaa... l~ tb6 cabin~· Ct.1tlft ~tl..S. i:~~• .. . 

.~~ 0£ ~ uu.-.~·the !Uct .U.Ji.c~n-BOIBi.plaoed: 111 operaticm. Sa . . 

DtJton, ~· · (fti-. 1~# a ~Clll'erurmc of ~lch had been deftl.0)>84 

ill U..K.~ WU a ~eed-..l;JUeal -cb\n• 4ep&'bl• Of Ntching a 

...-.d plaSn. text aplaft. tbe encipb.el'ecl ~ of a -G•?llall FIIQFA 

.._ .. £0~ tlls. PUIJlO.H of •uinfnt take ~ vhe8l. set.Ung.} !he 

UM delq 1n r£ad.inJ I1CIOM tnttio _. cut froll m ~· or 600 .. 

· U... to abo11t l60 hoara. (t,;ee .b&:&V nd horizontal' line On. cbart.) 

.. 
' ' 

REF ID: A6565. 

_. 

. . 

.. in refuallDg .. eel.&. Qlt9d !Ve• could alsa ~'brought _Id.thin 

-.f.fediTe range ot .their 09 March eq~ for &\~ack• against the - ' . - - - - . 

aut:au1aes. v-boat. loa~ in cmsequ.ence contiaaed 1;o ~ b1fb· 87. 

Stip~ ot 1'U, ·'.\he -Uir$. ~· ~. op~ting 1ri tuil i'o!°• iJt . 

VUh~ton, therebi.&r•tl.7 a~ting t.he comb1:n~ ~ .Uo~ ·am_ 

· the tiM l.ag in reading G&l'mD. waagea 11&4 alalihed \0 an aTerage ot 72 

. - - . boura'. !Ile Coablned C!pher Kacbine (~), lll\ro4'aced tor eollbilled 118p . .. - . . 

:rear. 

Reavlta Ot t.heae .aela:iffwni.8 were felt. in 'th. Oman opera"oDal. 

pic'twe -.t- a-. iltholJ&b b v-boa\a :ret.waed once again. to the Jfortll . . 

·1~t1c 8blpp1ng lanea 1n e:onaidenbl• force,, the '!P seriice could. : . 

m loqer l.ead tlam to the Jllled "mn'078• .£111ed ships ad planes., 

aided 'bJ'·intelliglllce .hm. COIIft eourc•,, con,inUld the· offmai•e 

•£&iJ:i•t ~e ti-boat. and lo._ .coatmued heav for 'the tleruns. Ia 

~, !ih• divertec:l their U-boata to the v.1. - Gibraltar ~ipptng 

. ' 

ia.,. baring been driTen ou\ of Um ·ffoioth Afil.azttic. -tllll"lml U-boat. 

auaages were now being nad continur:n•ly, cot1plete17, and C'Uftlen\17.J 

iii ~ ho'~ on the awnge. !tie r--U.•. higll-grade operational radio 

eoaUD1cationa ·were nev: v1tla apen '° 1he Alllu. B8aid8a .lpplJhg 

h1'Nllt. oper&tional tntonau.on. EBIGlll -saga rnul.ecl 11lftl.able 

- . - temd.eal lDtelliPnce om.cend11g the ·u.-boat pro8ftL !be .&111911 ... · , . 

'.ba4. a aovce of a~te an4 CGllpreheuiYe into:mat1on on nev weapona., 

. -·· 
• REF ID:A6565i 

. eucb as tihe acoust,ic torpedo~ aa ~ a1 ~- Db 4e'ricea · suah ·u 

.earch receifti.a and. the *Cbnordwl Up.rSaenta~ ~dth tM 10.. Ot 

their ow CCHV..~ aourc:ea, naulting ~ inc~e4 .l1li.ect c01J1r.111leatlcn ,. 

securitq au'bseq~~ to general ~tribd!m of the Coabined Cipw 

~chine• t.he ~ vere forced t.o nl,J alaM\ ~ttnl.J .an cermaa 

Air Jib~ _reoonnal. .. nc• for locating CcnnoJa., But tbl• alternati,e_ ~ · 

.· proftd wh ·lff5 att..Un -u.n CfMift~ and. Allied: .id.pping lo-• in ::: . . 

. the Ati'lantic• ~or ei.&'-~ wtu 1Julmlquen\ t.o t..U-1Cale ~t.1on f# 

tll• BOJl11'.C,. W81'e cut io aa aTEra~e of ._. 27,ooO taos~P..·maidib. 

·in ~DN7 1~hh, t.be ttrn -~~ tt-~t appearec1 ·ift· th. 1 ttaat10 -

b1I\ the ~el .s.iada at ._ tlel'e mt. aat.1efaotor1l1 CClllpl.eted - . . 

. tmUl after U. . .Aμi.M 1mald.aD ot Jt'l'Uce. 'D'le acbnorcbel ~t cl1d. 

mt. b110M a aeri.ou tJana~ and ~Sng loe"• CGDtinued at a loV 18"1. 

'Ill• .&lliu aont.in•ct '° aintas.n the ·~tap durf.ag t.he critical · .. - . . .. . . 

1lllU1a priod. ·(LOMu -.n ao ISiliU. bJ' Ima ·191W \!Jat. the chart 

no longer ahovis' tAn .N"a ~ •. ). u.bU.t: loa8u •. 0n th• -~t.het' bad,. 

~ aonAdmU7 ~'17·. 'Ole Diu CO!IUaud thdr. excelllllt vork · 

of NCOYering dall,- kq •t'1.Dga tor the IJflCM. and the ti.me 3- nn_. 

again £.μ beht»cl a b8 hov ~- ~or ett~tlft __ .opaat!onal ~. -' . . 

117' AUfUS\1 the U.bo.9.ta M4 be8n eracated troa t.btdr po:rt.a on the · ·. . . . 

Pftnob ~oaet, ·~ the r.ei.n adersca fleet, -. greatly reduced after ·. 

16 eon'8Cllt.1w -tba or l'tJYel'aea. 

JJeep1te ~ aetbacka, •• ~er.an.·~·. am cont.1Due~ its . . 

~a.• to zregaia .,ei.101"1\7• i.t · .-.· a laat-4.tt~ «ft'on vu Jllda . . - . 

·a the autumn ot lAI& to res• uie otfe~1:.e b7 uaSne the .~ 

.fl-beau, which iv- tb\a u.. · W8ft ateadil)' tncreutng ·in maber •. 
/. 

-:!~·--··~ ~. REF. ID: Ji.65651 •. - . . .... ,, •. 

,. . _ . .. . . . '6:8 ~ ~I a ~f-' .. t fiQ(·'.•Jfd~ 

lj ~ •''f G· .. •§=;. -~ • . . • . • :'I • - -

Coatuldcation-tdae, ··~• van ude in 4en'UU'T 19lt.S ~t.h a aev 

tJPe ot t.rnna!.Plolt, tbe . ·~-- . tranud.uicta, 1n an -ai.telrp\ to 

pnrt'mt. intercept.ton ':It U-boat ~ges. . 1h• 

, •kurier" was ·a. -a~stm . . . --

ot filtr...blfh·SJ*d ~ ·wfl.aahtt tzoaruminien~ 1n which a brW-but. · .. 

o o • I • • •i. 

sea• of unat '11. tain .mGre th.,- •taad11J' 1ncreaaed ,~ 'ilmber• &lll .. . . 

ettecti'ftftfrSE. '.bt. tbe ... of the •r .. ~a fev lGOntba" oft. . . . ~ 

~Ced .ldth totai. coilap.e 1ft the hoael.and, t.be ODOe poWflll 'tr-boa\ .. . . . - .. - . . - .. 

~•et vaa .forced ~ . .-.Jtftd411' ill_ March ot 19bS• a1.\bo'1& lt.. -~ ·~Ull 

. a ~. COllbat mi~ well orpnhed, illpro~- and 11!l>int to . . . . . , . 

oont:ln• the'-'• 

Wld.l.e .1't 1~. not feasi\lli.t io.· Maas preel-17 tll• ftl.118 fd C!llttft. 

Sn t1le Wt.la<>! tile !.?tlan~o, certa!lt irNult• dram fl'o.11 operational 

·~ baft indicated ta\ the. aftilabU.ttr ot t.1M17 deo17Pt1on 

:intelllgeiee to t.ibe ~ 11-taon• ~ b)' a :aSaS._ ot· 2SOJ t.lldr 

-ettecti..;. aeari:h abUtty •i&lna\ COftWJB •1p.clal17' ..i.ctea tor - . . 

a\\aolt on \be baa1a ot ~ucb. !atelltgcca. Tbh aul.JSia ha• al• 

rewalect that· during the period or idgb readabU1t.,- b7 tile .ua... 1'!m 

- ' 

£eptealm' 191&.3 to llareb ~9Lk1 tbe corita~t Tate of GerUn U-bo~ta _. . . 

tao-thirds th&\. ot the rate d.l.l'ittg tile J.ut. •ix mrntba of 19"21 1lhen 

th• Alli• are mt read1Dg U.boat ~~cat.1.Gna. ~. ~ . - . .. - - . - . . 

a. u. period or hip .NadabUit1· bs tu Jilt~•·· th. •inking rate 

(per U-bo&t. uT p'(.-r. cOnT01 daJ') .dropped to :o,....:lxt.h !Jf the. - pr .. 

_ ~iI•tt troa JJJ1T ~? Dseeamr lfla ._ ii~JPt.iOn s.aw1tgtn•• ..... .. . 

n-ailable to the t..Mns ba not to tlae 1.1.l.1•• 
?• ..,.- - . ~ -· ~F ID:A6565i 

• < • • - -

AaW. ~m the'ftt\ aaT1np nalil.\inf ma \?48 .,.., ... 1D 

_.tt.U••- ot tile lJ-1.&u dUring tu perS.odll of AD1 .. et"Mlft 

' . 

.' . ..,.au~. Th• ertectJ. ...... of h UatW avt&oe and as.tr 

~·ctitna ·tvcn ~·h _.. ••llat$le m u. At.lallua - &Nau,. ..__,,._and ~ ~ _in _f'ual ~.,. tas.• .to.rcee .-. · 

acab1e'f9d. 

·>