. REF ID:A6565~ . emorandum .• UNITED STA~BS GOVERNMENT Op-32.'i!r/rdw TO ~WENGER (V'lce Director, BSA) DATB: SSO/Y-137 J APR 1953 PB.OM I CAPr ROEIER ( Op-322!) ·.. SUBJECT: Ol!lG Report :/168; forWard1Dg of Encl: (1) Dir., OEG Report ser (L0)2271-52, undated (2) OEG Report :/168 l. Enclosures (1) and (2) are forwarded herewith for 1nformt1on and retention. /2;..B. F.7. RCEDER Page l of 1 Page Copy L of 2 copies roved or release b NS on 08-23-2013 ursuantt E .0. 1352 (I.,0)2271.. .52 Fro.Ill: Director, Operations Evaluation Group To; Op-03D Via: Op-)22Y subj: Forwarding of Enclosure (1), Ogerat1ons Evaluation Group Regort 68, TOP She:R!lf ef.dfelo Encl: (l) OEG Report. 68: 1val~at1on ot the Role ot Decr,ption Intelligence in tAe Operat1ol181 Phase of the Battle ot the Atlant1oo lo The attached report, prepared at the request of op-03D and Op=)~2Y 0 should be viewed as an eX&Dlple of the kind ot intor­ inlltion whioh can be obtained by an extensive study of the data extracted from the decryptions by both tb.e Germans and tne Al• lies Of .radio COaQlUWliO&tions pertaining tO t.b.e Operations Of tbe German sub.marines aea1nst Allied shippi.ug. This study has established e nwu.ner of conclusions ot wide general interest to all those concerned with the Radio war, and w1t4 the con4Qct ot anti-submarine 09erati0Aa, ~o No effort is·made here to recapitulate tlle findings ot this study on the use of decryption intelligence to our own torces and to convoy sa1'ety, since t.tleae s..ibJeots are covered in tb.e swnmar1 of the repor~, part 5. fheae t1'1..4inss warraAt ca~Qf..Ml reconsideration~t the oonoJ.usLaAs reached lnCilliiFS~~n w~iie_!ft~itil or--acoryptioA 1ntelilgelioe "'Were not ts!Cen in- to acooLWt. --- -------- -- ·-----··------.... )o D1stribut1~n of the attached report to all properly cleared staff agencies concerned with snt1-submar1ne warfare and sub­ marine opera tion.s is recommendecle JAOIN'l'O STI!:INHARM', Director, Operations £valuat1on.Groupo T 0 P S E C R E T GANOi; Tot' 5WlmT L ~F :w~~6AOE~ (Lo)2211-s2 ?'f- 0 t -~:CCI\: ~ SECURITY INFORMATION OPERATIONS EVALUATION CROUP REPORT 68 !.'VALUATION OF THE ROLE OF DWRYPTIOI-1 llfl'ALLIGENCE IN THE OP.ER/\TIONAL PHI.SE OF THE BATTLE OF Till; ATLANTIC T 0 P S E C R E T CANOE· 'PeP s:&;s1m' O ~F :W ~~~o E 4t-- (L0)22?l=S2 r ~:CCI\: -· SECURITY INFORMATJQri TA -o:r CONTENTS BillLJ;OGliAPHY PREFACE INTRODUO'J:IION lo HISTORICAL SURVl!.Y 2o THE EX'DNT OP DECR!!>TED IMELLIGENOE AVAILABLEo 2olo To the Germans 2o2o To tlle Allies )o 'l'.HE UTILIZA.TlON OF DECRYPTION INTl!iLLIGENOE BY THE GERMANS. )olo The Etteot ot x-B Intelligence on the Oapabilit1 of UaBoats Contacting a Oonvcyo )ololo Effect ot X-B Intelligence on Probability at Co.ntaoto 3olo2o fhe Contact ooett1cient and Operational sweeprate~ 3o2o The Effect ot X-B Intelligence on the Attack Factor .· . and the Sinking Rate o 4o TBX VALUE OF DEORY.i.>TION INTJ!:IJ,IG'}l::NOE TO THE ALLlES. 4olo Strategic Use 4o2o Tactical Use in the Defense ot Oonvo7s. 4o3o Offensive Use 4o)olo HUAter-Xiller Operations against the U•Boatso 4o)o2o Allied Decryption Intelligence in Relation to the Destruction ot the German Refuelling Fleeto 5 o SUMMARY AND CONCLUSIONS. ANNEX to .Part 21 Section 2olo GKRt;A.N X-B INTELLIGENCE OF NOl:lTH A~LANTIC CONVOYS. ANNEX to part 2 1 section 2o2o DA.Y BY DAY SUMMARY OF ALLIED DEOHYPTIONS OF GERMAN U-BOAT MhSSAGES. ANNEX to part 3 o OP~TIONAL DA!rA. ANNEX to Part 4, section 4o)a JECRfPTIONS OH INDIVIDUAL U-BOA'l1S. T 0 P S E C R E T CANOE TOP Sl£mi! • 0 rFcI~: ~~5~L. '6 (L0)22?l-52 u .J.j ~ .J.. '- .&..I Jllll' SECURllY lNFORMATllN ! 1 1 Q Q ! ! ! !! x Ia SOURCliB Al .flermaa (a) X-B Beriolltea Weekly rep\)!'fiS ot the Ger.man decryption service (X-B DJ.enst)o Captured at e.nd or waro Extend trom 19)9 through Agril 19440 Complete record ot all German Raval 1ntell1geacea The deol'fptions deal al.most entlrel.J with convo1 movem.enbso (&eeret) o (b) 'l'he war D1aey of Betehlsbaber der_unterseaboote (Bero), (COJDmaDder ot Sub.marines)o From 19)9 through December 19440 (Caat14ea•ial)a Pl ~lie~ (o) Files by elate of Decrypted Messages .read by Op-20-)-GI(A)o (Top aeo~et Ul,ra)o (d) Dl1ly U-Boat Bstimateo COM'.INCB daily charts with U-Boat &lld convoy positions glottedo (Bocrei)o Ile REFERENCES (e) Account of U/B war froa December 1942 - May l94;a Co.m.p1le4 by Op-20....)··GI(A), dated 29 October 194Sa ('Pep See»et Vlt=a ) o . A ve17 oo.mprehensive, thorough» extre.mel1 interesting aocoUllt ot the task acoo.mplished by the group during World war Ilo It is in five volWDSs, as follows: ./' Volo I - Al.lied Oo.IWllWlioati~s Intelligance and the Battle of t.be Atlantioa A SWD018l.'Jo Volo II N U•l30et Operat1onso This is in five parts four dealing with auooessive periods in the Battie ot t~e Atlantic! and the fifth with blockade runners and German Nava Operations in the Fer East and Indian. Oceano The role ot decryption intelligence is descr1be.d throughout eaoh period, chiefly by means ot case histories ot particular convoyso There is a VeJ!7 comprehensive collection of these oese histories oovering the us ..tJK, US-Gibraltar, end UK~-Gib.l'altar conv01s at certain periodso B-1 T 0 P S E C R E T .CANOE ..... ~F ~~f;JO,.,~ '?Cf SBCRl'f ~ 0 r ~ n t I\:~~ (L0)227lftS2 CQUW11oation IDtelligance llD4 --sE£\}R\~1Jti0nAJJJ9!tOo.mpro.m1se ot Allied Cip.b.erso _ This volwae oon,ains a Vert interesting aocow:at ot the manner in w.b.10.b. Op-20-3-GI"(A) prove4 tllat the Allied messages were being rea4 by the Germans~ Vol. IV - Teo.bnioal Intelligence from All1e4 Co lcr I neecribea the contribution of Allied 4eo17ptlon 1ntelllgenoe oonoerni~S Ger.man UoBoat material and armament a . Volo V • TJ:Le German Naval Grid an4 Its Oiphero Ve17 interesting description of techniques ~sed in decoding the German grid cip.b.era .( t) G.c. end o•. s. Naval Historyo W;p See•e• Ul,:rao This ls a compendious aooount of the work ot the British Naval Intelligence Oftioe, 1n 24 volu.caes. A ve~y excel­ lent histor7 or tne u-Boa~ war is presented 1n Volume ./ XVIII, "The Battle ot the Atla.a.t10o" (g) ORG secret Memorandum No .. 18: rrequeacr ot attacks on Oo.n.voys in Relation to U•Boat Predioti~ns, 18 November l942o (h) ORG Seoret Memorandum mo .. 2S: A Probability Study ot OOMIHCH .Da117 Submarine Estimates, 27 February l94)o (1) OEG cont1dent1al Report No. 51: A.o.tis~bmarine wartare in world war II, 1946. ( 3) OEG cont1dcnt1al Report NO. ~6: Searob and screening, . 1946 (k)v G.c. and c.s. Naval 61.gintD Vol. VIIo - The German Navres Use ot Special Intelligence aad Reactions to Allied useo !le;t1 Deere~ Ul,no · Covers the subJeot in narrative form trom 19)8 to tne end ot the waro Contains so.me case histories ot speoitio appl1cat1ans ot Ger.man deoryptions of Allied Rlo In ad= dition to t.be weekly X•B reports, the author .tlad available the captured daily files of German decry~tso !OP 6l!SHii9;' B•2 PRllC-NSS-3U6 TOP SECRET~· SECURITY INFORMATION PREFACE This report contains the findings of research carried out with the general obJective ot determining in what manner and to what extent th.a aveileb1lit7 ot intelligence derived trom the deor7pti~n ot intercepted radio messages affected the conduct ot the U-Boet wer against North Atlantic convoys on the part of both belligerents. The speo1t1c purpose ot the research can be most olearl7 steted by giving the oircum.stanoes connected with the genesis of the projeoto Dllring World War II the Antisubmarine Operati~ns Research Group (ASWORG) was organized tor the pl.lrpose primarily ot analyz= ing operati:>nal data as thef were assembled in the course of the war against the Germ.en subm.erines, 14 :>rder to provide information that would be ot assistance in adapting strategy and tactics so es to utilize the available A/S foroes with maximum. etteotivenesso In the course ot tb.is work, /.S\"M'OHG found it necessary to devise measures of efteotiveness tor the various aspects of the A/S operations--as an example in dealing with the detection ot the enemy, subjects or study by ASWORG included the construction ot systematic searcn plans tor surtaoe vessels and aircraft; the evaluetion ot the means ot deteotion--visual, rader, sonar; studies ot tne most profitable areas ot search, etc. At the end ot the war, the most ialportant results ot tlle various studies carried out by ASWORG were assembled and published in two comprehensive reports: reference (i) dealing chiefly with the several aspects ot the war against t.b.e u-Boats trom a statistical vi.ewpoint; and reference (J) presenting a complete end coherent theory ot search and screening operations developed on the basis ~t the operational data assembled during the war. To be efteotuel ~perations research requires as complete operational data, bolh own end ene.1111's, as possibleo The results ot intelligence in general were, ot course, .made available to.