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German Radio Intelligence•

ALBERT PRAU N

A senior German officer's view of communJcat;ons inreJ/lgence operations In 1he Nonh Afritan and Europe.an thearers of the &cond Wnrfd War.

THE SIGNIFICANCE OF ELECTRONIC WARFARE

Toward 1hc end of World W1:1r II aboul 12,000 signal troops of the German Army were engaged io inlercepting lhe radio traffic of an increa,ingly powerful enemy. With the decline of the information gained by intelligence through aerial observalion, priwner of war interrogations, and reparts from enemy agents. communication imclligc:nce became increasingly important. In spite of the constant attempts of all the enemies to improve radio communication and increase its security, German signal troops were able again and again to gain access to the information transmitted by this medium.

Thanks to communication intelligence. German commanders were better informed about the enemy and his intentions than In any previous war. This was one of the factors which gave the German command in the various campaigns of World War II a hitherto unattained degree of security. ·me fact that, during the final years of the war when the German Army Command was leading exhausted and decimated troops without reserves, it was able to offer less and less resistance to clearly recognized measures and intentions of the Allies, and that Hitler was unwilling to acknowledge the true si1uation on all fronlS and the growing enemy superiority as rcponed in accura1e de1ail by communication incelligence, is one of the deep tragedies of the German soldier.

• Lieu1cnan1 General Alben Prnun served ~s Germany's Chtef of Army and Armed Forces Sienal Communka1ions from 1944 10 the end or 1he Second World War. This ar1iclc is 1aken from a hi'1ory of the same litle prepart.d for 1he. His1orical Division, Headquanus, European Command. U.S. Anny, aru.J la1et released by the Oflke of 1he Chief of Mili1ary Hhstory. Readers will note references added by lhc 1r2nsl.t1or of 1ht1 original (tr.I and by lhe editor of lhe Technical 1011.rnal[td.}. No effort hM been made 10 amend General Praun·~ le>tt 10 reflect rcx:cn1 >AOr!c. on communica1io11s 1nrelhgcncc and its role in the Second World War. Some minor changes in spelling. punctuation, and wording ha\'c been made. and 1ht te>tt has been abridged 10 fOCll

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GERMAN RADIO INTELLIGENCE

3 8 2:7 0 0 31HERCEPT OPERATIONS AGAINST GREAT BRITAIN (1940- 411' After lhc conclusion of the Campaign in the Wcsl OK H (Oberkommando

des Hceres , "Army Command") ordered Army Group A to initiate rad io inlclligence operations against the British Isles . This intelligence mission, which was gi\len in rhe form of a preliminary order on 2 July 1940, was supplemented by mid-July with requests for 1he following specific infoona-tion : present l~ation of former British Expedi1ionary Force uni1s : org.aniz.a· lion , s1rength and disposition of Regular Army and Territorial Army forces in lht: Bri1ish Isles, as well as of forces shipped 10 England from 1hc Dominions, with special empha.'iis on Canadian troops; tran.~fcr o f units from the tMther country for service in the Near East {Balkans) and Middle East (Egypl and North Africa)~ defensive measures initiated by permanent coastal defense forces and mobile defense forces; and coverage of the channel coast. this ~ing the immediate objective for a German invasion in accordance wilb plans for Operation Scelocwc. t (The operations of 1he assigned inlerccpt units , including intercept, areas are shown in Chart I.)

In spite of intensive searching during the first four weeks (July 1940), it was impossible to intercept any messages of the k.ind which hnd been sent by mobile elements of the British Expedillonary Force on the Continent. To be sure, a few messages were picked up, but they could neither be followed for any length of time nor assignfd to any regular net traffic, and frequently they were so brief as to preclude even the taking of accurate bearings. The few messages intercepted, though encrypted in a rather simple field cipher, were not enough for cryptanalysis purposes. Jn the final evaluation these observations .. were interpreced to mean that 1he seriously decimated divisions or the British Expeditionary Force firs1 had 10 be reorganized. re-equipped and reh

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3 e 2 7 0 Qo~: The Down

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3 8 j2 7 Q Q ~! Canadians had to a large e:

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3 8 2:7 0 0 3:chanically transmitted ·message~. Since it was no longer possible to solve ~~.em. work on th~e mes~gcs was discontinued.

In 1he summer of 1942 1he British introduced new radio cechniques. which wen: also widely adopted by the Americans. At El Alamein the British caprnred the entire equipment of the intercept company attached lo lhe German Africa Corps. A.'i will be explained at length in the section on Arrica. they recognized their former miski.akes and quickly corrcc1cd them on all fronts. However, rhese new methods were not inrroduccd everywhere simultaneously, but at first only in Africa. Geiman inLercep1 1roops in west.em Europe were thus able to adjust 1hemselves in rime. German communication intelligence now encountered considerably more difficulties in evaluaring the 1raffJc. Call signs and frequencies were changed at irregular intervals, which made it impossible to recognize inrer-nc1 rela1ionships. It required some lime and considerable experimental ion before other distinguish· ing characteriscics enabled German 1raffic arwlysis and direction finding unils IO overrofll(: tlJ~se difficullies. The numerous, informative messages in clear 1ex1 disappeared. One of the besl sources of intelligence were the e

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SE:GRE:T GERMAN RADIO INTELLIGENCE

successful for the next two weeks. Then this traffic ceased entirely. The British had become suspicious and did not resume radio operations until six weeks later, after couriers had been able to deliver new codes throughout this far-flung theater of operations.

The excellent results obtained by communication intelligence provided Field Marshal Rommel with accurate and welcome information, on which he could base his bold and varied tactics. His peculiar talent for gaining unexpected success in armored warfare, where radio communication played a vital role, had already brought him a number of startling victories as commander of a panzer division in the Campaign in the West. In the desert Rommel encouraged this new method of tactical reconnaissance, especially since the results of German air reconnaissance were limited by British air superiority. To facilitate the detailed evaluation of information by the intercept company, Rommel's chief of staff always had two field trunk circuits at his disposal to handle incoming telephone and teletype traffic. During all his inspection trips to the front Rommel was personally informed by radio about all important results obtained by radio intelligence. It may be assumed that the British did not employ any radio intelligence of their own against the German Africa Corps; at least they did not succeed in solving Rommel's codes. Thus, German radio intelligence was able to work unsuspected by the British.

Rommel also made use of radio deception by having several radio stations simulate large forces far to the south in the desert and suggest an encirclement. On repeated occasions radio intelligence was able to observe that the British were taken in by this strategem, and that apparently wirhout any confirmarion by their reconnaissance planes rhey sent tanks and motorized artillery, once even an armored division, to oppose the fictitious enemy. On one other occasion, however, German radio intelligence was unable to detect a British armored division which had advanced far to the south, since it had observed absolute radio silence for several weeks, as was subsequently confirmed by a captured regimental commander.

In front of El Alamein the intercept company was able to report the reinforcement of the British forces and their preparations for an attack with which the German-Italian forces could not possibly cope. The intercept company and its evaluation center were imprudently stationed far in advance of Rommel's headquarters and only a few kilometers behind an Italian sector of the front which was subsequently penetrated by British tanks in late Ocrober 1942. While defending itself the company lose more than a hundred dead; the company commander was seriously wounded and died in a Cairo military hospital. Because of the surprise achieved by the tank attack, there was no opportunity to destroy the valuable intercept files. Thus, the enemy captured the German records of intercepted British messages and codes and the analyses prepared by the German intercepted service, as well as German and Italian radio schedules and ciphers.

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AAOIO INTELLIGENCE OPERATIONS IN THE MEDITERRANEAN THEA.TEA

Morch 1943 .,.

GermJ• IU'tlu I• tilt Balklns openud 11nlu 1~ CHU•Hlu or CorutUDltaflDn l•l t Ulre-D re (Four) nbtmllD:ilt- to OB S.•1bwu1. Uni!$ assigud. 10 die AfriHn tbe-11u rtJQrl~, :1h•r f•bu111y 1943. 10 tll~ ComNnllltr ttl CoNNUK-lilions: lnltllicentt (Soo), nbo111Jn111~ II) OB South"n1 .

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GERMAN RADIO lr>TEUIGENCE

3 8 2 7 0 Q .§ep1 for 1hc rcsuhs oblained fmm observing 1he Brilish ~ighth Army. German rldio inrelligence had lillle suc1.:c:ss, inasmuch as nolhmg imponant could be in1ercept«1 except British command messages. which could not be solved. German radio intelligence worked togethc:r wilh its halian counterpart against the British. This cooperation was cx.tJemt:ly cordial, but furnished fC'w rcsul1s or any imponance.

The: proposal to supplement radio intelligence operattons. lhen directed exclusively againsl the east, by a chain of intercept sra1ions direc1ed 1oward the south and extending approximately from the Balearic Islands to Sardinia, Sicily, and Crc1e was rejected, since Anglo-American landings in Africa were believed ou1 of rhe question because of the "-utnerability of Allied supply routes to submarine auad .. In addition? there ~re supposedly not c:noug.h intercept units anilable for such a pree:tutionary measure .

The A1"cd landings in French West and North Africa on 7 November 1942 came as a surprise because of 1he secrecy afforded by radio silence. The unpred.K:tablc sky wai;c radia1ion on the short wavelengths, preferred by the British and Americans for miliiary uaffic. was responsible for accidental success on the part of German radio intelligence. The inLerccpt stations in Norway, the Netherlands. and France which covered the west, chiefty England, pick.ed up almosl all Allir::c.I messages following the landing and were able to work wi1bout the assistanc.c ,,f direction-finding stalions to lhc soulh. since a sufficient number of kx:alities were men1ioncd in Allied messages. On lbe first day of the landing lhe Bergen (Norway) Fixed Intercept Station received lbc messages with good signal strength. Bergen immediately recognized lheir impor1ancc and rcponed lhem 10 St. Germain. Since 1he 1raffic rescmblceachbtads, 1he neutralization or dtscnioo of French troops, the progress of the advance inlo the interior. some of 1hc: advance rou1es and objectives, supply proble-ms. coopera!ion bc1wccn air and ground units, the order of balllc uf the landing forces aod their tactical organi:i;ilion during the advance. Af1cr the Mriva\ of the first elements of General von Arnim's Fifth Panzer

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ALBERT PRAUN

Army. rc::ports were: ht:ard from armored reconnaissance elements about German positions. movements. and engagements. Addcd 10 these were the usual details. such as names of officers and rcpQrts on ca

DOCID· GERMAN RADIO l~TElllGENCE

' In lhis 3 8 2 7 QAJ13·cause he bdievOO lh

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w.:.c, :.u-wever, it was the real invasion. The Communication fntdligence Commander's rcques1 to save the

intelligence company in Africa from impending caprnre and thus preserve it for fucurc action by transferring it to ltaly was turned down because of Hiller's order 1hat no men or equipment were lo be CVCICUaled from Africa Thus, onJy a small pan of the valuable personnel and radio equipmen1 could be saved. The conduct of 1hc personnel of the company, with whom radio contact was main1

DOCID· 3827~ CiERMAN RADIO INTELUGfNCE ~i\·isiuns wen: ~ignetl a ~ccond one. The air liaison nelS were easy

10 mtercep1.. s_ince the syst~m used wa'> of a lower quah1y rhan tbat employed by the Rrir1sh and American ground fore~. This knowledge in lurn enabled the Ge~mans 10_ predict accurately when enemy auacks would begin. German ~Y m1ercep11on of Ehc Allied strategic air force revealed the points of ma1~- .effor1 of reconnaissance flighfs, and target areas, which helped 10 clacd) rhc enemy's overall plans.

~me trivia! details fu1:'1ished informarion to communication intelligence, a.s L'\ shown by the following examples. An impending allack against German defcn_ses m the Naples area was de.tected in time because a small supply unit

mcn11oned ~~I ~um was to be issued on a ccr1ain day. Since if was known chat lhe Brnish issued rum to their 1roops bdorc an allack, ic was possible to wnrn lhe German defenders.

The following was heard from a British sra1ion ar Lake Commachio: "The German troops are retreating in a hurry and even the Italians are advancing," The presence of the British uni1 was already known, but this message

con.firmed the first cmploymcn! of llalians in combar on the Allied side. The ~dio operator of a French uni1 described bis an1icipa1ed amorous adve.murt'.'s m _Naples. No French units had previously been delected at lhe poinl from which he ~n/ his message.

. If i~ difficult ro understand why the Allies. at feast during position warfare m _ 1h1~ _theater_, f~iled I~ mask 1ht!'ir offensive groumJ OpC"rnliuns by mam1~m1~g ra~JO silence JUSI as !hey did during surprise landings. Unlike rhc s1tua11on 1~ !he desen, their telephone lines in ftalr were certainly adequate for lh1s purpose. As was the case in Russia, this carelessness was ~roba_bly due to a feeling of absolute .supuioriry. Neverthcl~s, the manner rn which enemy radio operations were conducced offered 1be weaker defenders mu~h information which cost rhe auackcrs losses which could have been a\101ded.

DEFENSE Of W~CRN EUKOPE [1944-45-)

Following the .

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38~7003

ORGANIZATION OF RAD10 INTELLIGENCE UNITS UNDER 0 B WEST

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ALBE.RT PRAUN

thoroughly trained and experienced personnel. Breakdowns in the command net ca~ed by enemy air auacks reduced 1hc speed with whit:h in1elligence results were transmitted, bul 1his difficuil)' was overcome by a preartanged plan which wi:is put inio effect all along the line from the unn funhest forward back 10 lhc communication intelligence control center.

Af1er 1he initial laadings, long-range intelligence at firsc produced only minor resulls. 111is was explained by the fact thal lhc Allie..; did not wish to oiler an~· clues to enemy radK> intelligence and lhc:refore c~iricted their radio communication . Moreover. the short distances wiching the be-.l.Chhead .areas probably permiued the issuance of vertal orders and reports. In addition., the enemy was able co use le\ephone connections , which were not disrupted by any Luflwaft'e interference. The expansion of the beachheads resulted in the tra1lsmi.ssion of so many radio messages tha1 a fairly clear picture of 1he enemy siluatlon was speedily oi,rnined. An even grea1er wealth of informatioc was provided by short-range radio in1elligence and divlsional combat intelligence. Thi! signal offlcer for OB West moved his shon-cangc intelligence company 10 Seventh Army headquarters near Caen to improve short-rang~ in1elligi:::nce o~ra1ions. The reports on the situation cmaaa1ing from communica1ion inlclligcnce aboul forty-eight hours af1cr the beginning of the invasion lisccd mosl of lhC enemy divisions and included dala on the enemy army group chen in command.

The postwar pre5$ gave much attcn1ion to the opin~n expre:»ed by Gencrn.1 Jodi, the Chief of the Armed Forces Operations Suiff. who said chat a s-econd landing was eX~"Cled nonh of the Seine and that therefore tbe German reser ves l\Od the Fifteenth Army sta1ioned in that area were not immcdia1dy commilted in a counterattack . The information obtained by communication intelligence did not suppon this assumption . The chief of the control center of

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GERMAN RADIO INTELLIGENCE

3 8 2 7 a 1"'1:1'~isparchcd immediately; regardless or Lhc lime of day. Moreover. · · '-'.!~ unication lntelligence West was required 10 furnish a compilation of aii repor1s unfavorable to lhe enemy derived from calls for help, casually lis1s, and 1he Jike. When. during the firsc days or lhe invasion, American uni1s in par11cular sent out mcssges containing high casually figures. the OK W was duly impressed. Jn contrast, the estimate of the situation prepared by the Wcs1ern lmelligcnce Branch was absolutely realistic and in no way colored by op1imisric hopes.

As already mentioned. short-range radio intelligenct: and comba1 intelli-gence provided such an abundance or information rhar even in Normandy any atiack of division Slrt:ngth and greater could be predicred one to five days in advance. The American field cipher device was compromised. To be sure, messages. enciphered by this system could at first be solved only aner a delay of from 1wo 10 four days. La1er on, when more dara had been galhen::d, only a few hours were needed. The Brirish cryp!ographic service wt.IS unchanged: while the Army was as efficien! as ever. the RAF continued ro be careless. As in Italy. communication intelligence main1aincd routine interception of the ~ages sent by air liaison officers attached to Brit;sh Army hcadQuarrcr.;, who !hereby revealed the inrcntions of lht enemy command. There was no cryp1ographic cooperarion between the Army and the RAF, nor wa.-. 1here any unified conrrol in this field.

In spire of low personnel strength and disrupted signal communica1ion, German communicarion intelligence proved capable of covering che Allied forces· advance to the Rhine by reporting the approximate composition arid s1rength of lhe enemy unils as well .i.s the boundaries between forces of diWerent na1ionality. Baule--tested divisions were more careful in their radio operations than new ones. The Americans generally observed Jess radio discipline than the British, and thus provided a better source of informa1ion. During the first excitement of the invasion. both the Americans and the British of1en iransmjued in the clear. The Canadians, who formed the numerically weakest l

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3 8 2 7 0 oin~llcd how confidcn1 lhey were that the Germ:lnS would no longer be in • PStlmn lo atlack those Purls: or lhe front from which 1be.""e lroops had been withdrawn.

This phone and CW traffic provided addi1ional valuable information faler on, for example, when radio inrelligencc was able to predicc lhe transfer of a U.S. armored division lo lhe UCge-Aachco area 1wenty·four hours in advance.

Germa~ communica1ion intelligence coririnued 10 func1ion smoothly in !he Wes1 dunng the subscquen1 course of evenrs up to the end of the war. The Germans always knew well in advance abou1 enemy conccntrnlions, such as lhe one at [ht Rcmagen bridgehead . nnd abo ut Ute direction of tnrcndcd ar_mor t~rust~ .. ~hey had no difficulty in djsccrning. for CKample, where and wuh which d1v1~1ons ~encral Patton in1cnded 10 s1rike. The enemy gradually l:lbandoned e

DOCID· GERMAN RADIO INTELLIGENCE

3 8 2 7 Q QC.:9·1cteriltrl theit radio com~unication. The ~tandard of secwit)' in tbe ltah.:m theater was extremely high.

The U.S. Army

American radio communication developed very much along British lines. Up to 1942 dom~tic military traffic in the United States and thal carried on by the firs1 units to be transferred to the British 1sh:s revealed certain distinctive features.. such as APO numbers. officer promotion lists. and unit designa1ions and abbreviations which were a1 variance wi1h their British equivalents. German communication intelligence had no difficulty in driving wedges at points where these features occurred and in compromising the. security of American radio communication. The manner in which the U.S. Army handled the traffic showed that ils radio operators were fast and experienced. The commenis made in the pree