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While most didn't contribute much to the German war effort, the Navy's OKM did have some remarkable successes in breaking Allied codes. The 2. Abteilung der Seekriegsleitung included the Marinenachrichtendienst (M.N.D.) and its III. Abteilung, radio intelligence units. B-Dienst (Beobachtungsdienst, surveillance service,) and the xB-Dienst (decryption service) were primarily interested in the British Royal Navy and worked to break into British and other Allied secure radio communications. B-Dienst was created (early 1930s) and suceeded in breaking into Royal Navy codes (1935).
German efforts to read Royal Navy transmissions were impaired by the inability of largely land locked Germany to intercept Royal Navy signals in the Atlantic. The Spanish Civil War (1936-39) changed this. After the Spanish Civil War, Generalissimo Francisco Franco permitted Germany which had supported the Nationalists during the War, to set up wireless surveillance posts in Spain. Their primary purpose was to intercept Royal Navy communications in the Atlantic and Mediterranean.
At the outbreak of the War (September 1939), B-Dienst specialists had broken sufficent Royal Naval codes that the OKM was aware of the location of all fleet units.
B-Dienst continue to crack Royal Navy codes in the first years of the War.
B-Dienst used German city names as designations for the different British naval codes. “Köln” was one cover name; “München-Blau” and “München-Braun” were two other names. A four-digit American-British naval communications system was codenamed “Frankfurt”. The Royal Navy committed a cardinal mistake in that they did not regularly change their codes on a timely basis.
B-Dienst regularly read the transmissions of ships using the British and Allied Merchants Ships (BAMS) code. Allied nations included occupied countries (Norway, the Netherland, Belgium, and Greece). The ability to read this traffic was of greater importance than Royal Navy ships. The Germans did not have surface ships of taking in the Home Fleet in a major fleet engagement. The U-boats could, however, attack merchant shipping if it could be located. The Atlantic is a big ocean. The U-boats no matter how cleverly position would have expended a great deal if their effort finding ships. Merchant shipping intercepts were an invaluable assett during the early phases of the Battle of the Atlantic when the U-boat fleet was still quite small.
B-Dienst broke into the code used for many Atlantic convoys (Februry 1942).
The U.S. Navy had refused, for security reasons to equip Royal Navy units with the new ECM Mk.1 encryption devices (194). The Royal Navy thus decided to use Naval Cypher No.3 for Allied radio communication and Atlantic convoy operations. B-Dienst focused its resources on the new code. They broke into it (September 1942). The Kreigsmarine thus had access to the convoy transmissiions (December 1942-May 1943). This was a critical phase in the Battle of the Atlantic.
One source suggests that the Germans were reading something like 80 percent of the intercepted messages. Time was, however, a critical factor. While B-Dienst had cracked into the code, the process they were using took time. Only about 10 percent of the messages were decoded in time for the U-boats to act on them. Even more importantly they never learned that the British were reading German naval transmissions.
At the same time that the Allied transmissions went dark, Allied anti-submarine warfare (ASW) began to wreak havoc on the German wolf packs. B-Dienst also broke British Naval Cypher No.5 as well as several low-grade British Naval codes.
While most German code breakers didn't contribute much to the German war effort, the Navy's OKM did have some remarkable successes in breaking Allied codes. The 2. Abteilung der Seekriegsleitung included the Marinenachrichtendienst (M.N.D.) and its III. Abteilung, radio intelligence units. B-Dienst (Beobachtungsdienst, surveillance service,) and the xB-Dienst (decryption service) wwere primarily interested in the British Royal Navy and worked to break into British and other Allied secure radio communications. B-Dienst was created (early 1930s) and suceeded in breaking into Royal Navy codes (1935). It was originally located in Berlin, but was later moved to the village of Eberswalde.
Wilhelm Tranow is a name only the most avid World War II reader will recognize. He is in fact one of the most sucessful code breaker of all time and with much more limited resources than Alan Turing and the other Bletchley Park code breakers. He began his career as a radio technician aboard a World War I German battleship and was reprimanded when he began on his own independent work on code cracking. The Navy soon changed their mind (German Naval Intelligence Service) at Neumünster. After the War he was one of amall group the Navy retained to work on codes. That group formed the basis for what would become B-Dienst. Interestingly, when Hitler became Chancellor (1933) he ordered the Navy to direct its code breaking effort on the French as he hoped to conclude an alliance with the British. In the inter-War era, Tranow studied the British Navel code and he was able to use his detailed knowledge of British Naval movements and gained importan insights by using 'Lloyd’s Weekly Shipping Reports' in its asessment of intercepted trnasmissions.
To break codes and ciphers you need to intercept transmissions, a lot of them, so they can be abalaied. German efforts to read Royal Navy transmissions were impaired by the inability of largely land locked Germany to intercept Royal Navy signals in the Atlantic. Mussolini's adventure in Ethiopia (1935) and the Spanish Civil War (1936-39) changed this. As a result of Mussolini's moves, the Royal Navy moved ships into the Medsiterranean (1934). The crisis became worse has the year progressed. Italian troops were at the border of Ethiopia. Britain and Framce instituted an arms embargo, which moatlty affected Ethiopia as they did not manufactyre modern weapons. There had been a weapons embargo by Britain and France which handicapped Ethiopia's ability to fight the well-armed Italian invasion forces. The Royal Navy redepoyed to the Mediterranean to give it the ability to defend attacks on British possessions (Gibraltar, Malta, and Suez. The British moved their base to Alexandra. Navel ships were deployed from other stations around the world. The Italian took Addis Ababa in May 1936 but war between the Royal Navy and the Italian Navy did not happen. The League of Nations led by Britain and France refused to take forceful action, basically appeasing Mussolini despite his use of poison gas. This increasing Royal Navy activity in the Mediterranean, however, gave the Germans the ability to intercept and work on more messages. First Sea Lord Jackie Fisher thought war was a good opportunity to practice tactics. The first thing which was done was signals. The peace time 5 digit code cipher was changed to a war situation code. In a war situation the code was changed to a double coded cipher. This was what the Royal Navy did in Aden during the Ethiopia crisis. The coded British messages were picked up in the German Navy’s most Southernmost B- Dienst listening station in the Black Forest town of Villengen. Tranow and his colleagues used this as a great opportunity to work on the British War time codes. He and his team were able to strip away the 5– digit code to read the 4 digit meaasge code. He had the newspaper reports about the navel units in Aden and Alexandra. B-Dienst operative knew that this was the only region using this code. 【Boyle】 German aid to Generalissimo Francisco Franco's Nationlists gave the Germans access to even more Royal Navy transmissions. Franco permitted Germany to set up wireless surveillance stations in Spain. The purpose was to intercept Royal Navy communications in the Atlantic and Mediterranean. This significantly increased the number of messages the Geramns had to work with. In addition, the Royal Navy was part of an international force observing the Spanish Civil War. Again the war time code was used and it gave B- Dienst code breakers the opportunity to untangle the coded signals. By the end of 1936 the British Naval Code system was broken and the Germans could read the Royal Naval war time coded signals from then on, (despite cipher changes which were cracked) until 1943. 【Boyle】 This was Naval Code No. 3. The British found out that it had been broke, butb also how difficult it was to replace.
It took time but Tranow expert knowledge was useful in eventually breaking the Royal Naval War situation cipher.
As a result, at the outbreak of the War (September 1939), B-Dienst specialists had broken sufficent Royal Naval codes that the OKM was aware of the location of all British fleet units.
B-Dienst continue to crack Royal Navy codes in the first years of the War.
B-Dienst used German city names as designations for the different British naval codes. “Köln” was one cover name; “München-Blau” and 'München-Braun' were two other names. A four-digit American-British naval communications system was codenamed 'Frankfurt'. The Royal Navy committed a cardinal mistake in that they did not regularly change their codes on a timely basis. B-Dienst broke the British and Allied Merchants Ships (BAMS) code (1942), This was of normous imprtance because it maent thar Dönitz could track the convoys and cdirect the U-boat attacks.
B-Dienst regularly read the transmissions of ships using the BAMS code. Allied nations included occupied countries (Norway, the Netherland, Belgium, and Greece). The ability to read this traffic was of greater importance than Royal Navy ships. The Germans did not have surface ships capable of taking in the Home Fleet in a fleet engagement. The U-boats could, however, attack merchant shipping if it could be located. The Atlantic is a big ocean. The U-boats no matter how cleverly position would have expended a great deal if their effort finding ships. Merchant shipping intercepts were an invaluable assett during the early phases of the Battle of the Atlantic when the U-boat fleet was still quite small.
B-Dienst began breaking into the code used for many Atlantic convoys (Februry 1942).
The U.S. Navy had refused, for security reasons before America entered the Wra, to equip Royal Navy units with the new ECM Mk.1 encryption devices (1940). It was developed for the U.S. Army in the late-1930s. The Navy was aprised of the work (194) and had a working version (1941). (The machine was also known as the SIGABA or Converter M-134 by the Army, or CSP-888/889 by the Navy, and a modified Navy version was termed the CSP-2900.) The Royal Navy thus decided to use Naval Cypher No. 3 for Allied radio communication and Atlantic convoy operations. B-Dienst focused its resources on the new code. They broke into it (September 1942). The Kreigsmarine thus had access to the convoy transmissiions (December 1942-May 1943). To make matters worse, this was just when the German expanded U-boat building campaign was beginning to turn out the number of U-boats Dönitz assured Hitler he needed to defeat the British. This was thus a critical phase in the Battle of the Atlantic. One source suggests that the Germans were reading something like 80 percent of the intercepted messages. Time was, however, a critical factor. While B-Dienst had cracked into the code, the process they were using took time. Only about 10 percent of the messages were decoded in time for the U-boats to act on them. Even more importantly they never learned that the British were reading German naval transmissions. B-Dienst also broke British Naval Cypher No.5 as well as several low-grade British Naval codes.
The British eventually learned at the catastrophe security breech and tightened their codes as well a adopting American electronic coding systems. The British and American naval codes shifted onto a telex based system which remained secure to the end of the War. The Germans reied but could not break the American system. -At the same time that the Allied transmissions went dark, Allied anti-submarine warfare (ASW) began to wreak havoc on the German wolf packs driving the Germans from the North Alantic sea lanes. .
The Royal Navy introduced Naval Cide No. 5 (1943). B-Dienst was unabkle to crack it and it remained un broken for the rest of the War.
Boyle, David. Operation Primrose.
Kahn, David. Seizing the Enigma: The Race to Break the German U-Boat Codes 1939–1943 (Annapolis, Maryland: Naval Institute Press, 1991). .
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