Thursday, September 27, 2012

The Finnish cryptologic service in WWII

Finland was part of the Russian Empire in the period 1809-1917. In December 1917 the Finnish declaration of independence led to a civil war between the Reds (supported by the Russian Soviet Republic) and the Whites (supported by Germany). In 1918 the anti communist forces won and Finland became an independent country.

From then on the Finns had to defend their freedom from the newly established Soviet Union. The need to keep an eye on their powerful neighbor forced them to show special interest in radio interception and cryptanalysis.

Tuesday, September 25, 2012

German knowledge of operation ‘Overlord’ - Compromise of British diplomatic code?

The Allied invasion of Western Europe in WWII was codenamed ‘Overlord’. The Germans learned of this through their spy in the British embassy in Ankara, Turkey. This spy was controlled by the Sicherheitsdienst’s foreign intelligence department.

General Schellenberg, head of this department, describes the whole affair in his memoir. After learning the codename of this operation the Germans were naturally keeping an eye for messages that referred to it.

In page 390 of his memoirs he says about the files that Cicero copied from the ambassador’s safe:

The contents so impressed me that at first I devoted myself entirely to the study of the documents and almost forgot to initiate those measures which must be carried out by the chief of a Secret Service in such cases. However, I then ordered:

(a) the immediate presentation of the reports to Hitler through Himmler.

(2) General Thiele (Chief of the Wireless Security and Decoding section of the Wehrmacht Supreme Command) to visit me at once to receive the material, which would enable him to start work on deciphering the British diplomatic code (The four greatest decoding experts in Germany, two professors of mathematics among them, worked on this material for weeks until finally they were able to 'crack' a part of the code. It was a tremendous achievement. Especially revealing were a number of handwritten notes on the margins of the documents, technical data on code messages from London to Ankara. Such things were of the greatest value to our experts.)

In page 393 he says:

In the meantime, by using the documents we had been able to decipher part of the British diplomatic code. One of the first important pieces of information we found in 'Cicero's' material was that the planned invasion of France was to carry the code name Operation 'Overlord'. After the first appearance of these words in the document, I immediately conferred with General Thiele. He at once started operations that would enable us to determine where and when the code word 'Overlord' appeared in the enemy's short-wave communications.

However his postwar interrogation by the Allies, summarized in ‘Hitler's Last Chief of Foreign Intelligence: Allied Interrogations of Walter Schellenberg’, p251 says:

Schellenberg maintains that he has never seen deciphered British messages. He has learnt that the last successful deciphering was that of British messages which went by W/T from Cairo to London. After that a coding machine was introduced in Cairo which abruptly prevented all further deciphering. General Thiele had continuously asked Schellenberg to provide him with an English code machine or an English diplomatic or military attache code still in use, but Schellenberg never succeeded in getting these.

So which version is correct?

Sunday, September 23, 2012

Book Review - Stopped at Stalingrad

The Luftwaffe was one of the most interesting aspects of the German war machine. Built from the ground up in the 1930’s it dominated the skies over Europe in the first half of the war. Even in the latter part, when it was grossly outnumbered by the Allies, it continued to fight on till the last day of the war.

In the East the Luftwaffe played a vital role by establishing air superiority, supporting the ground troops at the front, bombing important targets deep behind enemy lines and keeping the enemy under constant observation with its recon planes.

Unfortunately the full effects of the Luftwaffe’s efforts in the East are not usually mentioned in most books.

Stopped at Stalingrad closes this gap by covering, in great detail, the operations of the Luftwaffe in the summer campaign of 1942. The author Joel Hayward is an expert on Luftwaffe history and operations.
The first chapters cover the German conquest of the Crimea in the summer of ’42 and show the great contribution made by the Luftwaffe.  Using airfields in the Crimea aircraft could operate throughout the day on one fuel load and only landed to reequip with bombs. Thanks to massive air support the Soviet forces in the Kerch peninsula were defeated and Sevastopol leveled.

In May ’42 a surprise Soviet attack in the Ukraine using their armored forces was soundly defeated thanks to swift Luftwaffe intervention.

The rest of the book deals with the German attack on the Caucasus and details the countless missions that the Luftwaffe had to perform every day.

When the Soviets counterattacked at Staligrad and the 6th Army was surrounded, it was up to the Airforce to provide supplies. Hayward is one of the few authors who cover the Stalingrad supply missions in detail.

Finally the book ends with the German counterattack in the Ukraine in early 1943. The ground troops again received outstanding support from their Airforce.

In all these operations the Luftwaffe played a vital role thanks to its ability to generate a very large number of sorties from forward airfields. Especially the ground attack units under General Wolfram von Richthofen acted as flying artillery.

The book was a best seller for a reason. It is highly recommended for anyone interested in the Luftwaffe and/or the Eastern Front.

Wednesday, September 19, 2012

Army Command and Administrative Network, IBM Radiotype and APO numbers

In war efficient and secure means of communication are vital for any undertaking. Without the ability to communicate quickly with his underlying units a general will lose control of a battle. Without the ability to control faraway units a military command will see its forces attacked and destroyed piecemeal.

WWII historians tend to focus too much on tanks and aircraft while at the same time neglecting the huge effort made by the warring nations to build up modern communication networks.

During the war the US Signal Corps built up a modern worldwide communications network for US military and diplomatic authorities. This network was called ACAN (Army Command and Administrative Network).

ACAN linked centers in London, Hawaii, New Delhi, Karachi, Chungking, Algiers, Cairo, Basra, Casablanca, Accra, Asmara and other areas with the War Department Signal Center (codename ‘WAR’) in Washington.
For the rapid transmission of messages several types of equipment were used. Initially hand Morse and Boehme (rapid Morse) equipment, then radiotype and finally the modern radio-teletype (enciphered).

It was thanks to these networks that the Allied commanders could efficiently command their forces all over the globe.

German interception of ACAN networks

These networks were monitored by the German signal intelligence agencies and both plaintext and cipher traffic was intercepted.

Due to the very large number of messages passing on these networks some important information was always available in plaintext transmissions. In addition some of the hand codes used could be ‘broken’.

It also seems that the Germans repeated their ‘Russian Fish ‘success by building a special device that automatically intercepted and printed the teleprinter traffic.

There are few details on this affair but I’ve tried to collate all the available information.

From postwar interrogations it seems that at least 4 agencies intercepted and evaluated this traffic.

1). The Army Ordnance, Development and Testing Group, Signal Branch Group IV C  -  Wa Pruef 7/IV C at an experimental station in Staats.

2). The Signal intelligence Agency of the Supreme Command of the Armed Forces - OKW/Chi.

3). The Luftwaffe Signal Intelligence agency’s LN Abt 350 Referat B in Asnieres, Paris and later Munich-Oberhaching and a special unit operating from Berlin-Schoenfeld.

4). The Army Signal Intelligence agency - OKH/GdNA from bases in Norway and Euskirchen, Germany.

Wa Pruef 7/IV effort:

The Wa Pruef 7/IV C department has been mentioned before in connection with the ‘Russian Fish’ equipment. It was headed by Bau Rat Kierkhoff and according to a postwar interrogation there were about 5-6 engineers, 7-8 other men and 60 odd Nachrichtenhelferinnen (women helpers).

Report FMS P-038 ‘German Radio Intelligence’ says that the Staats station intercepted Russian, British, American and French radio-teletype systems.

This traffic was passed on to OKW/Chi and OKH/GdNA for analysis and evaluation.

OKW/Chi effort:

Wilhelm Flicke a member of OKW/Chi mentions in his book ‘War secrets in the Ether’ the interception of US overseas traffic.

In pages 295-6 he says:

Of the "big fry" the USA provided its enemies most amply with information. Among other things a special radio network had been set up in 1942 which covered the entire globe. This was the "WVNA-net" (named from the call-sign of the station in Karachi, India, which was the first one heard.) Most of the exchange of messages could be read currently; it afforded information on American military measures in the Far, Middle, and Near East and in Africa. The following survey shows the extent of the network in November 1942:

WVNA -net

call sign, location, cover name and interpretation 

Washington      agwar = Adjutant General, War Department

                            milid = Attache

                            crypto = Secret communications service

                            victor = Proper name, (head of "crypto") "Signatures: Arnold, Cambela, Groninger, Kroner, Loughry, Marshall, Ohnstaed, Osborn, Reybold, Sommervell, Strong, Ulio.


wvna                                    Karachi (India)      speck        =   proper name 

                    Signatures : Jordan (Vice-Consul) ,Wheeler (General and head of the USA military mission).


wvmt                           Basra (Iraq)            amsir        = American military section Iraq

                                                                            Signature : Connoly (Vice-Consul)


wvnv                    Cairo  (Egypt)          amsme    = American military Section Middle East


wvnt                Asmara (Formerly Italian-East Africa)      amseg    = American military Section



wvmy                Teheran (Iran)                            amrus  = American military Section Russia

                                                                                         Signature:  Ondrick ( Mil.Att.)


S9x                          Delhi (India)                      aquila = Cover name for American air forces.

                                                                         ammdel = American military mission Delhi

                                                                        amobsin = American military observer  India

                                                                   Signatures: Tiger, Speck (only there for a short time)


nekci                    Chungking (China)     ammisca  =  American military Section Karachi Office in  Chungking         

                                                                               amilat   =   American military attaché

                                                               Signature : Stilwell ( General and Commander of US Forces in China)

                                                                                         Barret (Military Attache )

                                                                                             Gauss (Ambassador)


J7z                                     Kunming (China)           ammkun  =    American military mission Kunming.


Bud                          Gura (formerly Italian East Africa)     amgad    = ?

                                                                                               Signature: Bishop,Signals.

Flicke is obviously describing ACAN. This is confirmed by the ‘Signal Corps-The Test’ which also mentions the same stations, for example: ‘After the Signal Corps' first large transmitter in India, at Karachi, had begun operation in April 1942, satellite stations rapidly sprang up.’ and ‘The direct WAR to Cairo (WVNV) circuit, after barely two months of service, was discontinued on Christmas Eve 1942 in favor of relay of the Cairo traffic by way of Asmara (WVNT).’

Unfortunately he doesn’t expand on the kinds of traffic being passed on these links or the codesystems used. However we know that OKW/Chi could decode several US diplomatic codes during the war.

Luftwaffe Chi Stelle effort:

The Luftwaffe Signal Intelligence agency‘s LN Abt 350 Referat B in Asnieres, Paris intercepted USAAF and Naval AF traffic both Morse and radio-teletype. This section reached its peak in terms of importance in 1942-3. Then in 1943 the part that dealt with USAAF ferry traffic was split up and sent to Munich-Oberhaching.

The section of Referat B which was moved to Munich-Oberhaching in 1943 was named Referat B5. There was a large intercept station monitoring USAAF ferry traffic close by.

European Axis Signal Intelligence in World War II’ vol5 gives more details on the operations of Ref B5:

The new Section evaluated all traffic and had the following responsibilities: a) The monitoring of the United States proper, which although it only touched the surface, still furnished an insight into the principal networks of the Army and Naval Air Forces, into training activity, air transport, defense zones, and the activation of new combat aviation units. b) The monitoring of the Atlantic ferry service. The Middle and Central Atlantic routes were monitored by the W/T platoon in Oberhaching and by Luftwaffe Signals Intelligence Service outstations in Spain, which operated under the cover name of ‘Purchasing Agencies’; the North Atlantic route was monitored by the 16th Co., LNR 3 and reports furnished to the Section. c) The monitoring of the American Air Transport Command by the platoon in Oberhaching. d) The monitoring of the RAF Transport Command and of both American and RAF troop carrier commands. The greater part of this interception was also done in Oberhaching.’

US radio-teletype was also intercepted by a LN Abt 350 unit in Berlin-Schoenfeld. The types of traffic intercepted were FF5 and FF6, which refer to 5-unit T/P and Radiotype respectively. A German report from November 1944 says that the Schoenfeld unit had 14 Rhombus installations, an intercept hut with 12 intercept rooms and total strength of 52 men. Intercept equipment was provided by Wa Pruef 7.

In postwar interrogations German personnel mentioned that USAAF T/P ferry traffic was read during the war.

Friedrich, head of Luftwaffe signals intelligence, stated in TICOM I-13:

 KAMERUN’ (CHI Stelle Ob.d.L., Referat B) when located at PARIS-ASNIERES had intercepted and broken U.S. non-morse teleprinter traffic between WASHINGTON and EUROPE. This success was maintained throughout owing to the lamentable insecurity of the operators. The Germans had therefore always known all details of ferry flights, strength of the U.S. Air Force in Europe and a good deal about training and replacements.’ and ‘Yes. It was wireless teleprinter traffic from Washington State Department. No. Not to Europe: to overseas W/T stations. It was a 'Zutraegerverkehr, (traffic passing on signals in bulk). There was an immense volume of traffic. Breaking ceased when a new machine or a new 'Tastschritt’ (keying tempo ?) was introduced. Yes, there was a secrecy device, but it could be broken by the most primitive methods; there were 10 GAF WAAF only to cope with it. The traffic did not carry signals of any tactical importance. No, this was not before, but after, the Americans entered the war. But breaking ceased a long time ago. Yes, a special receiver had to be built. 'As far as I can remember, but I don't want to be bound to the statement, the receiver was built for me by a Feldwebel'. The alphabet was a kind of morse substitution. What should have been A came out as, say, M. No, it was not this impulse business.

The follow-up report I-29 says:

1. Reference was made to Friedrich's previous statements about the breaking of an American "Funkfernschreib" system. See Ticom/I-13. ((Note: as will be seen, the whole difficulty about this claim arose from his use of the quoted term 'teleprinter' when he meant in fact 'undulator', and from a misunderstanding about the terminals of the traffic)). He was asked when the breaking began, and stated that it was shortly after the entry of the U.S. into the war. It was traffic between the War Dept and the regional traffic collecting centers, he could not recall the locations of these centers, but they were all within the United States. They were specifically not in Iceland or Greenland. The transmission was described as teleprinter ((wrong)) short-wave. It was encinhered but was easy to break. It was Morse traffic, not impulse. It was recorded by teleprinter ((i.e. undulator)) on a printed strip as dots and dashes [but see below]. This was enciphered morse, not clear text. He had a special receiver built by a Feldwebel for taking it. it was multi-channel [but see below]; he does not know what kind. The contents of the traffic were: training instructions, development of airfields and details of selective service processes.

2. He was asked whether this was the traffic from which he had said they got details of ferry flights; it was, particularly details of the preparations for flights and of the routes. The traffic dealt with the bringing of aircraft to assembly points, then their transfer to ferrying ports, and finally with their flights to North Africa, Gibraltar, and later straight to Great Britain.

3. Was the morse just scrambled for transmission, or was there a cipher underneath? Didn't know. After unscrambling the channels, did you have clear text, or was there a further encipherment to solve? Reply: there is a misunderstanding. The multichannel scrambling method to which we referred is the method used by the Americans later on, and which the GAF failed to break, because of lack of apparatus. The traffic in question was originally just Plain morse. The new "Tastschritt" affected only the German interception, not us. Asked to define Tastschritt, he said it did not mean "keying speed", but the synchronizing of the intercept equipment with the recorder. He was asked to explain the inconsistency of his referring to the traffic both as teleprinter and as morse. He then drew a picture of an undulator tape, single-channel, and marked off the undulation into successive Morse letters. He said this was what he meant by Funkfernschreib. Each letter was different from the corresponding clear text letter. He could not remember any of the indicators. The preamble gave ample routing instructions, and enabled them to couple the names of towns with call-signs and personal names. The text itself was very stereotyped, especially the addresses. He did not recall whether cleartext was mixed with cipher. He was asked whether they considered it a high-grade system, and replied that they did not, but that there was so much material in it, that if they could have allotted it sufficient time and personnel, they would have got a good deal of valuable information from it. It dealt in addition with the production and development of aircraft. However they had other things to do, and other sources of information, so this materiel was not fully exploited. We asked what these other sources were. He said all of the ferry-flight air-ground traffic was read by III/LN Rgt 3 also in Sicily and gave expected times of arrival and departure, weather, and strength of groups of planes being ferried.

4. It was asked whether the morse signs on the undulator were converted into letters or figures. They were letters. When did the breaking cease? He found this very difficult to recall. It was long before the invasion of France. We asked if it was before the invasion of North Africa. He said it was at just about that time, but he could not remember whether it was shortly before or shortly after. Asked what the change was, he could not recall. Was it to teleprinter or to multichannel. He thought it was not teleprinter as he had never had a receiver built which would take that. Question: Then they were still able to intercept it? Yes. In what form? Doesn't know. Still on tape? He thinks so. Who else intercepted this type of traffic-what other units? OKW did. In Husum? No. Dr. Pickering then said that FNAST 3 (Euskirchen) personnel had told a somewhat similar story (to be published). He replied that it was very likely that this was the same traffic, as KAMERON (unit intercepting for GAF) corresponded with Euskirchen on systems which they both worked on. He agreed with the Euskirchen statement that it was a simple substitution. ((Comment: Not too much credit should be placed in this statement, as he was just adopting a suggestion)).

Voegele, chief cryptanalyst of the Luftwaffe in the West said in I-112: ‘From April to October, 1944, clear radio T/P messages were intercepted regarding a/c movements between America and North Africa. similar messages in cypher with 6 letter indicators were also intercepted but these could not be read.

The Army Airways Communication Service

During the war special support was given to the AACS which belonged to the Airforce. According to the ‘Signal Corps -The Outcome’: ‘AACS differed from ACAN in that it was strictly an AAF organization, manned and operated by the airmen, though Signal Corps men supplied the equipment, engineered and set up the installations, and in the early days of the war often operated the communications lines too, until the AAF could do so with AACS men, who very often merely transferred over from the Signal Corps.’

It seems reasonable to assume that the networks exploited by the Luftwaffe belonged to the AACS. That would explain the traffic dealing with aircraft movements.

Apart from Morse, the AACS was provided with single-channel radio-teletype with automatic enciphering in order to deal with the traffic loads it transmitted daily. The official history ‘Signal Corps -The Outcome’ says: ‘It was the South Atlantic route to Africa and Europe that first got the single-channel RTTY net, along the string of Caribbean islands to the bulge of Brazil, across the South Atlantic via Ascension Island, reaching Dakar by mid-1943.’

OKH/GdNA effort:

The German Army’s Signal Intelligence agency - OKH/GdNA had a special group that intercepted high level enemy radio-teletype traffic. This was Group VI split into Referat 1 operating in the East and Referat 2 in the West.

The Ref 1 unit intercepted Soviet multichannel radio-teletype, both plaintext and enciphered, with special equipment. Members of this unit were captured in May ’45 by the Allies and taken to the UK with their equipment.

The Ref 2 unit was based in Euskirchen, Germany. This was the base of Feste 3 (Feste Nachrichten Aufklärungsstelle/Stationary Intercept Company).

According to report ‘CSDIC 1717’ Group VI Ref 2 was headed by inspector Heller and was divided in Ref 2A which evaluated the British and American T/P and automatic Morse traffic and Ref 2B that intercepted it. Roeder, head of Group VI at the end of the war, stated in TICOM I-99 that the Western unit had about 15 soldiers and 30 helpers plus 10 receiving apparatus.

US traffic was also picked up by Feste 9 in Norway. In report CSDIC/CMF/Y 40 it is stated that Feste 9 intercepted US traffic both manual and automatic from domestic bases and stations abroad (Atlantic area, Caribbean, Middle East, India).

Some of this traffic was enciphered with systems that the Germans had solved. These were the War Department Telegraph Code, the Division Field Code and the M-94 strip cipher.

There was a special device ‘funkfernschreibverkehr’ used by funkmeister Rudolph ‘an expert on WT TP intercept’.  This is a reference to the interception of Baudot radio-teletype and Radiotype.

IBM Radiotype, APO numbers and promotion letters

In order to build a modern communications network the Signal Corps wanted radio-teletype units with automatic enciphering and deciphering capability. In 1942 they did not have such equipment so they had to settle for a similar machine called radiotype.

From the IBM website:

The first working model of the Radiotype was fabricated in 1931 in the laboratory of Radio Industries Corporation under the direction of Walter S. Lemmon, who was then the company's president, Clyde J. Fitch, an engineer, and A. M. Nicolson.


In 1935 Admiral Richard E. Byrd successfully sent a test Radiotype message 11,000 miles from Antarctica to an IBM receiving station in Ridgewood, New Jersey. Six years later, IBM lent Radiotype machines to the U.S. Signal Corps for tests between Washington, D.C., and Dayton, Ohio. These tests were conducted by Albert Holt, an IBM field engineer in the Radiotype Division. With the U.S. entry into World War II, the Signal Corps ordered quantities of the Radiotype machines to equip its stations in San Francisco, Honolulu, Panama, Puerto Rico and elsewhere.’

The ‘Signal Corps-The Test’ says: ‘The International Business Machines Corporation had worked out an imperfect solution involving equipment that the firm called radiotype, using, unfortunately, not the standard five-unit teletypewriter code but a special six-unit code. Like a narrow gauge railroad adjoining a standard line, this special code necessitated much hand labor at conversion points where standard teletypewriter texts had to be shifted onto radiotype circuits, and vice versa. Moreover, the standard automatic cipher machines could not function with the six-unit system. Notwithstanding these inconveniences, the Signal Corps early in the war began making use of radiotype, leased from IBM. It was another step in the right direction, toward automatic, high-speed, heavy-duty communications for the Army.’
According to the same source the use of radiotype was extensive during the war: ‘Radiotype would continue to be used considerably. Not till September 1943 would the Signal Corps stop its procurement in favor of radioteletype and not until May 1945 would the Army take its last radiotype out of service (on the WAR-Accra circuit). Then the triumph of radioteletype would be complete.

The Germans were able to exploit the internal US traffic from 1941 onwards. The Army intercepted it from Euskirchen and from Norway.

By monitoring the internal US radio traffic the Germans could follow the activation and movement of units through their APO (Army Post Office) number. It was understood that divisions sent to West coast harbors went to the Pacific theatre while those sent to East coast harbors went to the Atlantic theatre. Valuable intelligence was also gained from officer’s promotion letters.
Initially this traffic was Morse but the introduction of radiotype forced the Germans to build specialized intercept equipment.

FMS P-038 says: ‘In the spring of 1942 a new transmitting technique was introduced in American long-distance communication (both domestic and foreign) that dried up this excellent source of German intelligence. The Euskirchen station, which was charged with cryptanalysis of this traffic, solved the riddle within one week, however, by means of tape recordings and systematic analysis. It was finally discovered that the process used was a rapid system of wireless telegraphy which differed from the usual method by the number of current impulses. This was the ‘Radiotype’ method. A tremendous number of military and business messages were soon intercepted. After a short while the receiving operators were able to ‘read’ the message tapes as fast as Morse code. Fortunately, after a pause of one week, military messages in clear text became more frequent for a time. This mistake was not discovered by the Americans until later, at which time they began to encipher these mechanically transmitted messages. Since it was no longer possible to solve them, work on these messages was discontinued.’
This may refer to the introduction of the SIGCUM cipher machine in early ’43 and its immediate withdrawal due to a security problem. Or it could refer to operator mistakes described in ‘The Signal Corps-The Outcome’: ‘The on-line features had a serious security disadvantage, however, in that the operator on the transmitting end sometimes forgot-when passing from unclassified traffic sent in the clear to classified-to flip the switch that would connect the on-line crypto equipment.’

The Germans did not always get good intelligence from ACAN. David Kahn says that the Allies managed to deceive them regarding the divisions sent to Britain in 1944 by sending fake radio messages. However he doesn’t provide more details.

On the other hand a member of Feste 3 named Wingender states in TICOM I-76 that even ‘fictitious stations and traffic’ were recognized thanks to violations of radio discipline and cipher security.

Radio-teletype and SIGCUM

Radiotype was only a temporary solution and from 1943 it was being replaced by regular 5-unit (Baudot) radio-teletype.

In order to protect this traffic the Americans developed a cipher attachment that automatically enciphered and deciphered the traffic. This device was called Converter M-228 or SIGCUM and was introduced in January 1943.

Its initial debut was not successful as a flaw in its security was found and a decision was made to delay its entry into service for several months.

It was finally put into use in April 1943. From then on ACAN teleprinter networks would be secure from eavesdroppers.

Unanswered questions

Although the information we have is enough to form a rough understanding of German operations there are many missing elements.

We lack details on the history and performance of the German agencies regarding their interception of ACAN.

What kind of intercept equipment did they use? How much traffic did they intercept? How much of it could they decode?

Did they attack the SIGCUM traffic cryptanalytically or simply use it for traffic analysis?

Another important question is whether the Radiotype system was used with a cipher attachment of some sort. Was that the simple substitution that the Germans talked about? We do know that standard cipher attachments could not be used on it because of its 6-unit operation.

Building IBM: Shaping an Industry and Its Technology’ says in page 348: ‘The use of Radiotype coupled directly to encryption and decryption equipment, is reported by J. C. McPherson. 8 August 1991: discussion with E. W. Pugh.’

Let’s hope that some of these questions will be answered in the future.

Sources: The Signals Corps trilogy (US Army publications), FMS P-038 ‘German Radio Intelligence’, ‘War secrets in the Ether’, CSDIC 1717, CSDIC/CMF/Y 40 , TICOM reports D-4, I-13, I-29, I-42, I-64, I-65,  I-76, I-78, I-99, I-104, I-109, I-111, I-112, I-149, Cryptologia article: ‘The Sigcum story: cryptographic failure, cryptologic success’ , IBM website, ‘Hitler’s Spies’, ‘European Axis Signal Intelligence in World War II’ vol4 and vol5

Tuesday, September 18, 2012


Time for some new TICOM reports:

D-4  ‘Summary of Relevant Items from the War Diary of OKL/Gen. Nafue. 3 Abt., June 1944 to April 1945'

I-13  ‘Interrogation of Oberst. Ltn. Friedrich’

I-29  ‘Third Interrogation of Oberstltn. Friedrich, Chief of the GAF Signals Intelligence Service’

I-41 ‘Report on First Interrogation of Major Oeljeschlaeger (various GAF Sigint appointments)’

I-42 ‘Report on Fourth Interrogation of Oberstltn  Friedrich (Head of OKL/Gen. Nafue. 3. Abt)’

I-70 ‘Paper on the German Sigint Service by Oberstltn Friedrich'

I-76 ‘Interrogation Reports on Lehwald, Haupts, Klett and Lauerbach’

I-98 ‘Interrogation of Oberst Randewig on German Deception plans’

Sunday, September 16, 2012

WWII Myths - Luftwaffe the tactical airforce part 2

The Luftwaffe was supposed to be a ‘tactical’ airforce that failed to invest resources in ‘strategic’ aircraft that could have won the war.

I’ve already criticized that opinion here. Throughout the 1930’s and 40’s the Luftwaffe spent the majority of its resources on the bomber arm. The best pilots were selected for the bombers.

Compared to the Allied airforces the Germans had superiority in technology and numbers at the start of the war. No other airforce had radio beam systems (like Knickebein and X-Gerat) for guiding bombers.

The Luftwaffe’s emphasis on the bomber force is mentioned in a postwar British study called AIR 41/10The Rise and Fall of the German Air Force (1933 to 1945)’

In pages 86-7 it says:
'The foregoing account of the Battle of Britain throws light on the main factors which contributed to the defeat of the Luftwaffe. It is as well, however, to enumerate those factors and to examine to what extent and to what degree each was responsible. The main factors may be summarized as follows:

(a) A fundamental failure in German air strategy and policy, which concentrated on the doctrine of attack, and thereby led to a disproportionate weakness of the fighter arm as opposed to the strength of the bomber and dive bomber forces. The armament of the German He 111, Do. 17 and Ju.88 bombers which, in conjunction with their speed, had been relied upon in part to offset the deficiency of fighters, proved inadequate and led to a wasteful use of the limited strength of the fighter escort and to disastrous quarrels at a crucial point in the Battle.'
While it is true that in the second half of the war the Anglo-Americans fielded large 4-engine bomber forces it needs to be remembered that the StrategicTM RAF only started getting its new 4-engine models in late 1941 and up to mid 1943 the operational numbers were between 200-300 planes.

So if the Luftwaffe was a ‘tactical’ airforce then that can only be true for the period 1943-45. This is understandable since from 1941 the Germans were involved in a life and death struggle in the East and had to spend huge resources on their land forces. Under these circumstances the Luftwaffe could not get the resources it needed nor could production facilities be allocated for aircraft that would take years to build and field in numbers.

Think about that next time someone says the Luftwaffe was a tactical airforce.

Wednesday, September 12, 2012

The British Interdepartmental Cypher

One of the high level British cryptosystems exploited by the Germans in WWII was the Interdepartmental Cypher. This was a 4-figure codebook enciphered with 5-figure subtractor tables.

The ID Cypher was used by the Foreign Office, Colonial, Dominions and India offices and the Services. Also used by the Admiralty for Naval Attaches, Consular Officers and Reporting Officers.

The Germans captured the codebook from the British consulate in Bergen in May 1940 and subsequently ‘broke’ the encipherment. Although their success was mainly based on cryptanalysis, they also received some enciphering tables from the Japanese in 1941.

All the German agencies (OKW/Chi, Forschungsamt, Pers Z plus the cryptanalytic agencies of the German Army, Navy and Airforce) worked on the ID Cypher and they exchanged results. During the period 1940-43 they were able to gain valuable diplomatic and military intelligence by reading the messages.

The Navy’s central cryptanalytic department OKM/SKL IV/III (Oberkommando der Marine/Seekriegsleitung IV/III) was able to decode the British Admiralty’s weekly intelligence summaries sent to naval attaches. In addition messages from the Freetown Area were decoded and provided intelligence on the movement of heavy ships and convoys. Traffic between the Admiralty and Consular Officers and Reporting Officers gave information on convoys and independently routed ships in the Atlantic. From ADM 1/27186 ‘Review of security of naval codes and cyphers 1939-1945’, p75-76

The Luftwaffe’s Chi Stelle read the communications of air attaches in the Near East, Portugal, Sweden and Switzerland. Maximum daily traffic was about 100 messages according to Ferdinand Voegele, the Luftwaffe’s chief cryptanalyst in the West. From TICOM IF-175 Seabourne Report, Vol. XIII. ‘Cryptanalysis within the Luftwaffe SIS’ Part 1, p21

Diplomatic messages were solved by OKW/Chi, the Forschungsamt and Pers Z. Interesting information was received regarding negotiations between Britain and Turkey.

The German efforts were assisted by poor British cipher practices. A security investigation in 1942 showed that the tables were overloaded, leading to heavy ‘depths’ and the indicators were not selected correctly.

The German success finally ended on 15 June 1943 when the codebook was changed.

Sources: ‘British intelligence in the Second World War’ vol2, TICOM reports I-12, I-22, I-172, I-119, HW 40/75 ‘Enemy exploitation of Foreign Office codes and cyphers: miscellaneous reports and correspondence’, HW 40/85 ‘Exploitation of British Inter-Departmental cipher’, ADM 1/27186 ‘Review of security of naval codes and cyphers 1939-1945’, ‘European Axis Signal Intelligence in World War II’ vol5, TICOM IF-175 Seabourne Report, Vol. XIII. ‘Cryptanalysis within the Luftwaffe SIS’

Sunday, September 9, 2012

RAF strength Med/Middle East - 1941-43

In the period 1941-43 the main theatre of war between British and German military forces was North Africa. There British forces had to fight against the German Africa Corps and the Italian Army.

The RAF strength during this period was the following:

Middle East Command and later Mediterranean Command


 North West African Air Forces

RAF - North West African Air Forces
Spitfire recon
Mosquito recon


Numbers refer to planes operational plus those serviceable within 14 days.

RAF Malta


Source: Daily strength reports from AIR 22 - 'Air Ministry: Periodical Returns, Intelligence Summaries and Bulletins'

Some comments:

Numerical strength goes up dramatically during the period 1941-43. From 385 fighters and bombers in May ’41, to 1.202 in May ’42, to 2.926 in May ’43 (including NWAAF).

In terms of quality the picture is not as clear as regards quantity. Even though the Brits have the excellent Spitfire fighter, in the Med they use the outdated Hurricane and the US P-40. Both these planes are inferior to the Bf-109. The Spitfire is finally used from mid 1942 but is only available in large numbers in late ’42.

The bomber force also suffers from mediocre quality. Initially it is made up of the outdated Blenheim and Wellington types. In 1942-43 the US types Boston, Maurauder, Baltimore, Maryland and Hudson are also used.

Standardization does not seem to be an issue with the RAF. In 1941 there are 2 fighter and 4 bomber types in use. In 1942 there are 6 fighter and 9 bomber types. Finally in 1943 there are 5 fighter and 8 bomber types.

Lend Lease plays a vital role in N.Africa, as the American P-40 fighter and the Boston, Maurauder, Baltimore, Maryland and Hudson bombers make up a large part of RAF strength in the theatre (roughly a third of ME Command in 1941-42).

Comparison with Axis strength:

Unfortunately I don’t have similar data for the Italian AF but Luftwaffe strength for Luftflotte 2 and Sud Ost has been posted here.

The RAF had a significant numerical advantage over the German AF, however that does not mean that the Germans were always outnumbered.

Against Malta the Luftwaffe could concentrate a large force of fighters and bombers operating from Sicily. In the first half of 1942 they had between 300-400 combat planes versus less than half as many British planes.

On the other hand in North Africa it was the Brits that had crushing superiority. The strength of Fliegerführer Afrika fluctuated between 200-300 planes versus up to 6 times as many in Middle East Command.

The Germans also faced serious supply problems that forced them to rely mainly on the Bf-109 and Ju-87. Bombers like the Ju-88 could not be permanently based in N.Africa but operated from Italy and Greece and were resupplied in N.African airports. The RAF on the other hand had the benefit of a large number of twin-engined bombers operating from N.African bases.