Ultra
Encyclopedia
Ultra was the designation adopted by British
military intelligence
in June 1941 for wartime signals intelligence obtained by "breaking" high-level encrypted enemy radio
and teleprinter
communications at the Government Code and Cypher School at Bletchley Park
. "Ultra" eventually became the standard designation among the western Allies
for all such intelligence. The name arose because the intelligence thus obtained was considered more important than that designated by the highest British security classification
then used (Most Secret) and so was regarded as being Ultra secret. Several other cryptonyms had been used for such intelligence. British intelligence first designated it "Boniface"—presumably to imply that it was the result of human intelligence. The U.S. used the codename "Magic" for its decrypts from Japanese sources.
Much of the German
cipher traffic was encrypted on the Enigma machine
. Used properly, the German military Enigma would have been virtually unbreakable; in practice, shortcomings in operation allowed it to be broken. The term "Ultra" has often been used almost synonymously with "Enigma decrypts
". However, Ultra also encompassed decrypts of the German Lorenz SZ 40/42 machines
that were used by the German High Command, and the Hagelin machine
and other Italian and Japanese ciphers and codes such as PURPLE
and JN-25
.
Many observers, at the time and later, regarded Ultra as immensely valuable to the Allies.
Winston Churchill
told King George VI
: "It was thanks to Ultra that we won the war." F. W. Winterbotham
, quoted the western Supreme Allied Commander, Dwight D. Eisenhower
, at war's end describing Ultra as having been "decisive" to Allied victory. Sir Harry Hinsley
, official historian of British Intelligence in World War II, made a similar assessment about Ultra, saying that it shortened the war "by not less than two years and probably by four years"; moreover, in the absence of Ultra, it is uncertain how the war would have ended.
and direction finding
. In the early phases of the war, particularly during the eight-month Phoney War, the Germans could transmit most of their messages using land lines
and so had no need to use radio. This meant that the British Government Code & Cypher School at Bletchley Park
were allowed some time to build up experience of collecting and starting to decrypt messages on the various radio network
s. Initially, German Enigma messages were the main source, with those of the German airforce predominating, as they used radio more, and their operators were particularly ill-disciplined.
" refers to a family of electro-mechanical rotor cipher machines
. These produced a polyalphabetic substitution cipher
, and were widely thought to be unbreakable in the 1920s, when a variant of the commercial Model D was first used by the German military. The German Army
, Navy
, Air Force
, Nazi party, Gestapo
, and German diplomats all used Enigma machines, but there were several variants. For instance, the Abwehr
(the German military intelligence service) used a four-rotor machine without a plugboard, and Naval Enigma used different key management from that of the Army or Air Force, making its traffic far more difficult to cryptanalyse. Each variant required different cryptanalytic treatment. The commercial versions were not as secure; Dilly Knox, of GC&CS, is said to have broken one before the war.
German military Enigma was first broken in December 1932 by the Polish Cipher Bureau
, using a combination of brilliant mathematics, the services of a spy in the German office responsible for administering encrypted communications, and a slice of good luck. Thereafter the Poles read Enigma to the outbreak of World War II and beyond, in France. However, at the turn of 1939 the Germans made their systems ten times more complicated, which required a tenfold increase in the Poles' decryption equipment, a need that they could not meet. On 25 July 1939, just five weeks before the outbreak of World War II, the Polish Cipher Bureau handed reconstructed Enigma machines and their techniques for decrypting ciphers to their French and British allies. Former Bletchley Park mathematician-cryptologist Gordon Welchman
has written: "Ultra would never have gotten off the ground if we had not learned from the Poles, in the nick of time, the details both of the German military Enigma machine, and of the operating procedures that were in use."
After the War, interrogation of German cryptographic personnel led to the conclusion that German cryptanalysts understood that cryptanalytic attacks against Enigma were possible, but they had been thought to require impracticable amounts of effort and investment. It was the Poles' early start at breaking Enigma, and the continuity of their successful efforts, that enabled the Allies to hit the ground running when World War II broke out.
teleprinter
systems for strategic point-to-point radio links, to which the British gave the generic code-name Fish
. Several distinct systems were used, principally the Lorenz SZ 40/42
(code-named Tunny) and Geheimfernschreiber (code-named Sturgeon
). These cipher systems were also successfully cryptanalysed, particularly Tunny, which the British thoroughly penetrated. It was eventually attacked using the Colossus computer
s, which were the first digital program-controlled electronic computers. Although the volume of intelligence derived from this system was much smaller than that from Enigma, its importance was high because it produced primarily strategic level intelligence.
cipher machine called the C-38
. This was broken from June 1941 onwards by the Italian subsection of the UK's GC&CS at Bletchley Park
.
theater, the Japanese cipher machine dubbed "Purple" by the Americans, was used for highest-level Japanese diplomatic traffic. It produced a polyalphabetic substitution cipher, but unlike the Enigma machine
s, it was not a rotor machine, being built around electrical stepping switches. It was cracked by the US Army's Signal Intelligence Service and disseminated under the codeword MAGIC
.
Some Purple decrypts proved useful elsewhere, for instance detailed reports by Japan's ambassador to Germany which were encrypted on the Purple machine. These reports included reviews of Germany's assessments of the military situation, of strategy and intentions, reports on direct inspections (in one case, of Normandy beach defenses) by the ambassador, and reports of long interviews with Hitler.
The chief fleet communications code system used by the Imperial Japanese Navy was called JN-25 by the Americans. By early 1942, the latter had made considerable progress into decrypting Japanese naval messages.
The Japanese are said to have obtained an Enigma machine as early as 1937, although it is debated whether they were given it by their German ally or bought a commercial version which, except for plugboard and internal wirings, was essentially the German Army / Air Force machine. The Japanese did not use it for their top secret communications, instead developing their own, similar machine.
- was compiled in summaries at GC&CS (Bletchley Park
) Hut 3 and distributed initially as "Boniface". The volume of the intelligence reports going out to commanders in the field built up gradually. Naval Enigma decoded in Hut 8
was forwarded from Hut 4 to the Admiralty
Operational Intelligence Centre (OIC), which were distributed initially under the codeword "HYDRO". The term "Ultra" was adopted in June 1941. The term "Ultra" was reportedly suggested by Commander Geoffrey Colpoys, RN, who served in the RN OIC.
Dissemination of Ultra intelligence to field commanders was carried out by MI6, which operated Special Liaison Units (SLU) attached to major army and air force commands. The activity was organized and supervised on behalf of MI6 by Group Captain Frederick William Winterbotham
. Each SLU included intelligence, communications, and cryptographic elements. It was headed by a British Army or RAF officer, usually a major, known as "Special Liaison Officer". The main function of the Liaison Officer or his deputy was to pass Ultra intelligence bulletins to the commander of the command he was attached to, or to other indoctrinated staff officers. In order to safeguard Ultra, special precautions were taken. The standard procedure was for the liaison officer to present the intelligence summary to the recipient, stay with him while he studied it, then take it back and destroy it.
Fixed SLUs existed at the Admiralty, the War Office
, the Air Ministry
and at RAF Fighter Command
. These units had permanent teleprinter links to Bletchley Park.
Mobile SLUs were attached to field army and air force headquarters, and depended on radio communications to receive intelligence summaries.
The first mobile SLUs appeared during the French campaign of 1940. An SLU supported the British Expeditionary Force
(BEF) headed by General Lord Gort
. The first liaison officers were Robert Gore-Browne and Humphrey Plowden. A second SLU of the 1940 period was attached to the RAF Advanced Air Striking Force
at Meaux
commanded by Air Vice-Marshal P H Lyon Playfair
. This SLU was commanded by Squadron Leader F.W. "Tubby" Long.
Arthur "Bomber" Harris, officer commanding RAF Bomber Command
, was not cleared for ULTRA. After D-Day, with the resumption of the strategic bomber campaign over Germany, Harris remained wedded to area bombardment. Historian Frederick Taylor
argues that, as Harris was not cleared for access to ULTRA, he was given some information gleaned from Enigma but not the information's source. This affected his attitude about post-D-Day directives to target oil installations, since he did not know that senior Allied commanders were using high-level German sources to assess just how much this was hurting the German war effort; thus Harris tended to see the directives to bomb specific oil and munitions targets as a "panacea" (his word) and a distraction from the real task.
started "Special Research Unit B1(b)" under Herbert Hart. In the SIS this intelligence was handled by "Section V" based at St Albans
.
, UK. Ultra summaries from Bletchley Park were sent over landline to the Section VIII radio transmitter at Windy Ridge. From there they were transmitted to the destination SLUs.
The communications element of each SLU was called a "Special Communications Unit" or SCU. Radio transmitters were constructed at Whaddon Hall workshops, while receivers were the National HRO
, made in the USA. The SCUs were highly mobile and the first such units used civilian Packard
cars. The following SCUs are listed: SCU1 (Whaddon Hall), SCU2 (France before 1940, India), SCU3 (Hanslope Park) SCU5, SCU6 (possibly Algiers and Italy), SCU7 (training unit in the UK), SCU8 (Europe after D-day), SCU9 (Europe after D-day), SCU11 (Palestine and India), SCU12 (India), SCU13 and SCU14.
The cryptographic element of each SLU was supplied by the RAF and was based on the TYPEX
cryptographic machine and one-time pad
systems.
RN Ultra messages from the OIC to ships at sea were necessarily transmitted over normal naval radio circuits and were protected by one-time pad
encryption.
, headquartered in Switzerland
and apparently operated by one man, Rudolf Roessler
. This was an extremely well informed, rapidly responsive ring that was able to get information "directly from German General Staff Headquarters" - often on specific request. It has been alleged that "Lucy" was in major part a conduit for the British to feed Ultra intelligence to the Soviets in a way that made it appear to have come from highly-placed espionage rather than from cryptanalysis
of German radio traffic. (The Soviets, however, via an agent at Bletchley, John Cairncross
, knew that Britain had broken Enigma.) The "Lucy" ring was initially treated with suspicion by the Soviets. The information that it provided was accurate and timely, however, and Soviet agents in Switzerland (including their chief, Alexander Radó
) eventually learned to take it seriously.
, but was learnt very quickly afterwards.
At Bletchley Park
, extensive indexes were kept of the information in the messages decrypted. For each message the traffic analysis recorded the radio frequency, the date and time of intercept, and the preamble—which contained the network-identifying discriminant, the time of origin of the message, the callsign of the originating and receiving stations, and the indicator setting. This allowed cross referencing of a new message with a previous one. The indexes included message preambles, every person, every ship, every unit, every weapon, every technical term and of repeated phrases such as forms of address and other German military jargon that might be usable as cribs
.
The first decryption of a wartime Enigma message was achieved by the Poles at PC Bruno
on 17 January 1940, albeit one that had been transmitted three months earlier. Little had been achieved by the start of the Allied campaign in Norway in April. At the start of the Battle of France
on 10 May 1940, the Germans made a very significant change in the indicator procedures for Enigma messages. However, the Bletchley Park cryptanalysts had anticipated this, and were able—jointly with PC Bruno—to resume breaking messages from 22 May, although often with some delay. The intelligence that these messages yielded was of little operational use in the fast-moving situation of the German advance.
Decryption of Enigma traffic built up gradually during 1940, with the first two prototype bombe
s being delivered in March and August. The traffic was almost entirely limited to Luftwaffe messages. By the peak of the Battle of the Mediterranean
in 1941, however, Bletchley Park was deciphering daily 2,000 Italian Hagelin messages. By the second half of 1941 30,000 Enigma messages a month were being deciphered, rising to 90,000 a month of Enigma and Fish decrypts combined later in the war.
Some of the contributions that Ultra intelligence made to the Allied successes are given below.
, the British Ultra unit was based in a large wooden hut in the grounds of Government House. Security consisted of a wooden table flap across the door with a bell on it and a sergeant sat there. This hut was ignored by all. The American unit was in a large brick building, surrounded by barbed wire and armed patrols. People may not have known what was in there, but they surely knew it was something important and secret.
To disguise the source of the intelligence for the Allied attacks on Axis supply ships bound for North Africa, "spotter" submarines and aircraft were sent to search for Axis ships. These searchers or their radio transmissions were observed by the Axis forces, who concluded their ships were being found by conventional reconnaissance. They suspected that there were some 400 Allied submarines in the Mediterranean and a huge fleet of reconnaissance aircraft on Malta
. In fact, there were only 25 submarines and at times as few as three aircraft.
This procedure also helped conceal the intelligence source from Allied personnel, who might give away the secret by careless talk, or under interrogation if captured. Along with the search mission that would find the Axis ships, two or three additional search missions would be sent out to other areas, so that crews would not begin to wonder why a single mission found the Axis ships every time.
Other deceptive means were used. On one occasion, a convoy of five ships sailed from Naples
to North Africa with essential supplies at a critical moment in the North African fighting. There was no time to have the ships properly spotted beforehand. The decision to attack solely on Ultra intelligence went directly to Churchill. The ships were all sunk by an attack "out of the blue", arousing German suspicions of a security breach.
To distract the Germans from the idea of a signals breach (such as Ultra), the Allies sent a radio message to a fictitious spy in Naples, congratulating him for this success. According to some sources the Germans decrypted this message and believed it.
In the Battle of the Atlantic, the precautions were taken to the extreme. In most cases where the Allies knew from intercepts the location of a U-boat in mid-Atlantic, the U-boat was not attacked immediately, until a "cover story" could be arranged. For example a search plane might be "fortunate enough" to sight the U-boat, thus explaining the Allied attack.
Some Germans had suspicions that all was not right with Enigma. Admiral Karl Dönitz
received reports of "impossible" encounters between U-boats and enemy vessels which made him suspect some compromise of his communications. In one instance, three U-boats met at a tiny island in the Caribbean Sea
, and a British destroyer promptly showed up. The U-boats escaped and reported what had happened. Dönitz immediately asked for a review of Enigma's security. The analysis suggested that the signals problem, if there was one, was not due to the Enigma itself. Dönitz had the settings book changed anyway, blacking out Bletchley Park for a period. However, the evidence was never enough to truly convince him that Naval Enigma was being read by the Allies. The more so, since B-Dienst
, his own codebreaking group, had partially broken Royal Navy traffic (including its convoy codes early in the war), and supplied enough information to support the idea that the Allies were unable to read Naval Enigma.
By 1945 most German Enigma traffic could be decrypted within a day or two, yet the Germans remained confident of its security. Had they known better, they could have changed systems, forcing Allied cryptanalysts to start over.
At least three versions exist as to why Ultra was kept secret so long. Each has plausibility, and all may be true. First, as David Kahn pointed out in his 1974 New York Times review of Winterbotham's The Ultra Secret, after World War II the British gathered up all the Enigma machines they could find and sold them to Third World countries, confident that they could continue reading the messages of the machines' new owners.
A second explanation relates to a misadventure of Churchill between the World Wars, when he publicly disclosed information from decrypted Soviet communications. This had prompted the Soviets to change their ciphers, leading to a blackout. The third explanation is given by Winterbotham, who recounts that two weeks after V-E Day, on 25 May 1945, Churchill requested that former recipients of Ultra intelligence not divulge the source or the information that they had received from it, in order that there be neither damage to the future operations of the Secret Service nor any cause for the Axis to blame Ultra for their defeat.
Since it was British and, later, American message-breaking which had been the most extensive, this meant that the importance of Enigma decrypts to the prosecution of the war remained unknown. Discussion by either the Poles or the French of Enigma breaks carried out early in the war would have been uninformed regarding breaks carried out during the balance of the war. Nevertheless, the 1973 public disclosure of Enigma decryption in the book Enigma by French intelligence officer Gustave Bertrand
generated pressure to discuss the rest of the Enigma–Ultra story.
The British ban was finally lifted in 1974, the year that a key participant on the distribution side of the Ultra project, F. W. Winterbotham
, published The Ultra Secret.
The official history of British intelligence in World War II was published in five volumes from 1979 to 1988. It was chiefly edited by Harry Hinsley, with one volume by Michael Howard. There is also a one-volume collection of reminiscences by Ultra veterans, Codebreakers (1993), edited by Hinsley and Alan Stripp.
After the war, surplus Enigmas and Enigma-like machines were sold to many countries around the world, which remained convinced of the security of the remarkable cipher machines. Their traffic was not so secure as they believed, however, which is one reason the British and Americans made the machines available. Switzerland even developed its own version of Enigma, known as NEMA
, and used it into the late 1970s.
Some information about Enigma decryption did get out earlier, however. In 1967, Polish military historian Władysław Kozaczuk in his book Bitwa o tajemnice ("Battle for Secrets") first revealed Enigma had been broken by Polish cryptologists before World War II. The same year, David Kahn in The Codebreakers
described the 1944 capture of a Naval Enigma machine from U-505 and mentioned, somewhat in passing, Enigma messages were already being read by that time, requiring "machines that filled several buildings."
Ladislas Farago
's 1971 best-seller The Game of the Foxes gave an early garbled version of the myth of the purloined Enigma. According to Farago, it was thanks to a "Polish-Swedish ring [that] the British obtained a working model of the 'Enigma' machine, which the Germans used to encipher their top-secret messages." "It was to pick up one of these machines that Commander Denniston went clandestinely to a secluded Polish castle [!] on the eve of the war. Dilly Knox later solved its keying, exposing all Abwehr signals encoded by this system." "In 1941 [t]he brilliant cryptologist Dillwyn Knox, working at the Government Code & Cypher School at the Bletchley center of British code-cracking, solved the keying of the Abwehr's Enigma machine."
By 1970, newer, computer-based ciphers were becoming popular as the world increasingly turned to computerised communications, and the usefulness of Enigma copies (and rotor machines generally) rapidly decreased. It was shortly after this, in 1974, a decision was taken to permit revelations about some Bletchley Park operations.
The United States National Security Agency
(NSA) retired the last of its rotor-based encryption systems, the KL-7
series, in the 1980s.
F. W. Winterbotham, the first author to outline the influence of Enigma decryption on the course of World War II, likewise made the earliest contribution to an appreciation of Ultra's postwar influence, which now continues into the 21st Century — and not only in the postwar establishment of Britain's GCHQ (Government Communication Headquarters) and America's NSA. "Let no one be fooled," Winterbotham admonishes in chapter 3, "by the spate of television films and propaganda which has made the war seem like some great triumphant epic. It was, in fact, a very narrow shave, and the reader may like to ponder [...] whether [...] we might have won [without] Ultra."
Debate continues on whether, had postwar political and military leaders been aware of Ultra's role in Allied victory in World War II, these leaders might have been less optimistic about post-World War II military involvements.
Knightley
suggests that Ultra may have contributed to the development of the Cold War
. The Soviets received disguised Ultra information, but the existence of Ultra itself was not disclosed by the western Allies. The Soviets, who had clues to Ultra's existence, possibly through Kim Philby
and Anthony Blunt
, may thus have felt still more distrustful of their wartime partners.
The mystery surrounding the discovery of the sunk U-869 off the coast of New Jersey
by divers Richie Kohler
and John Chatterton
was unraveled in part through the analysis of Ultra intercepts, which demonstrated that, although U-869 had been ordered by U-boat Command to change course and proceed to north Africa, near Rabat, the submarine had missed the messages changing her assignment and had continued to the eastern coast of the U.S., her original destination.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
military intelligence
Military intelligence
Military intelligence is a military discipline that exploits a number of information collection and analysis approaches to provide guidance and direction to commanders in support of their decisions....
in June 1941 for wartime signals intelligence obtained by "breaking" high-level encrypted enemy radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
and teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
communications at the Government Code and Cypher School at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
. "Ultra" eventually became the standard designation among the western Allies
Allies of World War II
The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...
for all such intelligence. The name arose because the intelligence thus obtained was considered more important than that designated by the highest British security classification
Classified information
Classified information is sensitive information to which access is restricted by law or regulation to particular groups of persons. A formal security clearance is required to handle classified documents or access classified data. The clearance process requires a satisfactory background investigation...
then used (Most Secret) and so was regarded as being Ultra secret. Several other cryptonyms had been used for such intelligence. British intelligence first designated it "Boniface"—presumably to imply that it was the result of human intelligence. The U.S. used the codename "Magic" for its decrypts from Japanese sources.
Much of the German
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...
cipher traffic was encrypted on the Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
. Used properly, the German military Enigma would have been virtually unbreakable; in practice, shortcomings in operation allowed it to be broken. The term "Ultra" has often been used almost synonymously with "Enigma decrypts
Cryptanalysis of the Enigma
Cryptanalysis of the Enigma enabled the western Allies in World War II to read substantial amounts of secret Morse-coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from other decrypted Axis radio...
". However, Ultra also encompassed decrypts of the German Lorenz SZ 40/42 machines
Lorenz cipher
The Lorenz SZ40, SZ42A and SZ42B were German rotor cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin. They implemented a Vernam stream cipher...
that were used by the German High Command, and the Hagelin machine
C-36 (cipher machine)
The C-35 and C-36 were cipher machines designed by Swedish cryptographer Boris Hagelin in the 1930s. These were the first of Hagelin's cipher machines to feature the pin-and-lug mechanism...
and other Italian and Japanese ciphers and codes such as PURPLE
PURPLE
In the history of cryptography, 97-shiki ōbun inji-ki or Angōki Taipu-B , codenamed Purple by the United States, was a diplomatic cryptographic machine used by the Japanese Foreign Office just before and during World War II...
and JN-25
JN-25
The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well...
.
Many observers, at the time and later, regarded Ultra as immensely valuable to the Allies.
Winston Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...
told King George VI
George VI of the United Kingdom
George VI was King of the United Kingdom and the Dominions of the British Commonwealth from 11 December 1936 until his death...
: "It was thanks to Ultra that we won the war." F. W. Winterbotham
F. W. Winterbotham
Frederick William Winterbotham was a British Royal Air Force officer who during World War II supervised the distribution of Ultra intelligence. Later, Winterbotham published the first popular account of Ultra....
, quoted the western Supreme Allied Commander, Dwight D. Eisenhower
Dwight D. Eisenhower
Dwight David "Ike" Eisenhower was the 34th President of the United States, from 1953 until 1961. He was a five-star general in the United States Army...
, at war's end describing Ultra as having been "decisive" to Allied victory. Sir Harry Hinsley
Harry Hinsley
Sir Francis Harry Hinsley OBE was an English historian and cryptanalyst. He worked at Bletchley Park during the Second World War and wrote widely on the history of international relations and British Intelligence during the Second World War...
, official historian of British Intelligence in World War II, made a similar assessment about Ultra, saying that it shortened the war "by not less than two years and probably by four years"; moreover, in the absence of Ultra, it is uncertain how the war would have ended.
Sources of intelligence
Most Ultra intelligence was derived from reading radioed enemy messages that had been encrypted with various cipher machines. This was complemented by material derived from radio communications using other methods, such as radio traffic analysisTraffic analysis
Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted and cannot be decrypted. In general, the greater the number of messages observed, or even intercepted and...
and direction finding
Direction finding
Direction finding refers to the establishment of the direction from which a received signal was transmitted. This can refer to radio or other forms of wireless communication...
. In the early phases of the war, particularly during the eight-month Phoney War, the Germans could transmit most of their messages using land lines
Landline
A landline was originally an overland telegraph wire, as opposed to an undersea cable. Currently, landline refers to a telephone line which travels through a solid medium, either metal wire or optical fibre, as distinguished from a mobile cellular line, where transmission is via radio waves...
and so had no need to use radio. This meant that the British Government Code & Cypher School at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
were allowed some time to build up experience of collecting and starting to decrypt messages on the various radio network
Radio network
There are two types of radio networks currently in use around the world: the one-to-many broadcast type commonly used for public information and mass media entertainment; and the two-way type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery...
s. Initially, German Enigma messages were the main source, with those of the German airforce predominating, as they used radio more, and their operators were particularly ill-disciplined.
German
Enigma
"EnigmaEnigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
" refers to a family of electro-mechanical rotor cipher machines
Rotor machine
In cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a prominent period of history; they were in widespread use in the 1920s–1970s...
. These produced a polyalphabetic substitution cipher
Polyalphabetic cipher
A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case...
, and were widely thought to be unbreakable in the 1920s, when a variant of the commercial Model D was first used by the German military. The German Army
German Army
The German Army is the land component of the armed forces of the Federal Republic of Germany. Following the disbanding of the Wehrmacht after World War II, it was re-established in 1955 as the Bundesheer, part of the newly formed West German Bundeswehr along with the Navy and the Air Force...
, Navy
Kriegsmarine
The Kriegsmarine was the name of the German Navy during the Nazi regime . It superseded the Kaiserliche Marine of World War I and the post-war Reichsmarine. The Kriegsmarine was one of three official branches of the Wehrmacht, the unified armed forces of Nazi Germany.The Kriegsmarine grew rapidly...
, Air Force
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
, Nazi party, Gestapo
Gestapo
The Gestapo was the official secret police of Nazi Germany. Beginning on 20 April 1934, it was under the administration of the SS leader Heinrich Himmler in his position as Chief of German Police...
, and German diplomats all used Enigma machines, but there were several variants. For instance, the Abwehr
Abwehr
The Abwehr was a German military intelligence organisation from 1921 to 1944. The term Abwehr was used as a concession to Allied demands that Germany's post-World War I intelligence activities be for "defensive" purposes only...
(the German military intelligence service) used a four-rotor machine without a plugboard, and Naval Enigma used different key management from that of the Army or Air Force, making its traffic far more difficult to cryptanalyse. Each variant required different cryptanalytic treatment. The commercial versions were not as secure; Dilly Knox, of GC&CS, is said to have broken one before the war.
German military Enigma was first broken in December 1932 by the Polish Cipher Bureau
Biuro Szyfrów
The Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
, using a combination of brilliant mathematics, the services of a spy in the German office responsible for administering encrypted communications, and a slice of good luck. Thereafter the Poles read Enigma to the outbreak of World War II and beyond, in France. However, at the turn of 1939 the Germans made their systems ten times more complicated, which required a tenfold increase in the Poles' decryption equipment, a need that they could not meet. On 25 July 1939, just five weeks before the outbreak of World War II, the Polish Cipher Bureau handed reconstructed Enigma machines and their techniques for decrypting ciphers to their French and British allies. Former Bletchley Park mathematician-cryptologist Gordon Welchman
Gordon Welchman
Gordon Welchman was a British-American mathematician, university professor, World War II codebreaker at Bletchley Park, and author.-Education and early career:...
has written: "Ultra would never have gotten off the ground if we had not learned from the Poles, in the nick of time, the details both of the German military Enigma machine, and of the operating procedures that were in use."
After the War, interrogation of German cryptographic personnel led to the conclusion that German cryptanalysts understood that cryptanalytic attacks against Enigma were possible, but they had been thought to require impracticable amounts of effort and investment. It was the Poles' early start at breaking Enigma, and the continuity of their successful efforts, that enabled the Allies to hit the ground running when World War II broke out.
Lorenz cipher
In the spring of 1941, the Germans started to introduce on-line stream cipherStream cipher
In cryptography, a stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream . In a stream cipher the plaintext digits are encrypted one at a time, and the transformation of successive digits varies during the encryption...
teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
systems for strategic point-to-point radio links, to which the British gave the generic code-name Fish
Fish (cryptography)
Fish was the Allied codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value was of the highest strategic value to the Allies...
. Several distinct systems were used, principally the Lorenz SZ 40/42
Lorenz cipher
The Lorenz SZ40, SZ42A and SZ42B were German rotor cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin. They implemented a Vernam stream cipher...
(code-named Tunny) and Geheimfernschreiber (code-named Sturgeon
Siemens and Halske T52
The Siemens and Halske T52, also known as the Geheimfernschreiber , or Schlüsselfernschreibmaschine , was a World War II German teleprinter cipher machine...
). These cipher systems were also successfully cryptanalysed, particularly Tunny, which the British thoroughly penetrated. It was eventually attacked using the Colossus computer
Colossus computer
Not to be confused with the fictional computer of the same name in the movie Colossus: The Forbin Project.Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II...
s, which were the first digital program-controlled electronic computers. Although the volume of intelligence derived from this system was much smaller than that from Enigma, its importance was high because it produced primarily strategic level intelligence.
Italian
On entering the war in June 1940, the Italians were using book codes for most of their military messages. The exception was the Italian Navy which, early in 1941, started using a version of the Hagelin rotor-basedRotor machine
In cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a prominent period of history; they were in widespread use in the 1920s–1970s...
cipher machine called the C-38
M-209
In cryptography, the M-209, designated CSP-1500 by the Navy is a portable, mechanical cipher machine used by the US military primarily in World War II, though it remained in active use through the Korean War...
. This was broken from June 1941 onwards by the Italian subsection of the UK's GC&CS at Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
.
Japanese
In the PacificPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
theater, the Japanese cipher machine dubbed "Purple" by the Americans, was used for highest-level Japanese diplomatic traffic. It produced a polyalphabetic substitution cipher, but unlike the Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
s, it was not a rotor machine, being built around electrical stepping switches. It was cracked by the US Army's Signal Intelligence Service and disseminated under the codeword MAGIC
Magic (cryptography)
Magic was an Allied cryptanalysis project during World War II. It involved the United States Army's Signals Intelligence Section and the United States Navy's Communication Special Unit. -Codebreaking:...
.
Some Purple decrypts proved useful elsewhere, for instance detailed reports by Japan's ambassador to Germany which were encrypted on the Purple machine. These reports included reviews of Germany's assessments of the military situation, of strategy and intentions, reports on direct inspections (in one case, of Normandy beach defenses) by the ambassador, and reports of long interviews with Hitler.
The chief fleet communications code system used by the Imperial Japanese Navy was called JN-25 by the Americans. By early 1942, the latter had made considerable progress into decrypting Japanese naval messages.
The Japanese are said to have obtained an Enigma machine as early as 1937, although it is debated whether they were given it by their German ally or bought a commercial version which, except for plugboard and internal wirings, was essentially the German Army / Air Force machine. The Japanese did not use it for their top secret communications, instead developing their own, similar machine.
Distribution
Army- and Air Force-related intelligence derived from signals intelligence (SIGINT) sources -mainly Enigma decrypts in Hut 6Hut 6
Hut 6 was a wartime section of Bletchley Park tasked with the solution of German Army and Air Force Enigma machine ciphers. Hut 8, by contrast, attacked Naval Enigma...
- was compiled in summaries at GC&CS (Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
) Hut 3 and distributed initially as "Boniface". The volume of the intelligence reports going out to commanders in the field built up gradually. Naval Enigma decoded in Hut 8
Hut 8
Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led initially by Alan Turing...
was forwarded from Hut 4 to the Admiralty
Admiralty
The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...
Operational Intelligence Centre (OIC), which were distributed initially under the codeword "HYDRO". The term "Ultra" was adopted in June 1941. The term "Ultra" was reportedly suggested by Commander Geoffrey Colpoys, RN, who served in the RN OIC.
Army and Air Force
The distribution of Ultra information to Allied commanders and units in the field involved considerable risk of discovery by the Germans, and great care was taken to control both the information and knowledge of how it was obtained. Liaison officers were appointed for each field command to manage and control dissemination.Dissemination of Ultra intelligence to field commanders was carried out by MI6, which operated Special Liaison Units (SLU) attached to major army and air force commands. The activity was organized and supervised on behalf of MI6 by Group Captain Frederick William Winterbotham
F. W. Winterbotham
Frederick William Winterbotham was a British Royal Air Force officer who during World War II supervised the distribution of Ultra intelligence. Later, Winterbotham published the first popular account of Ultra....
. Each SLU included intelligence, communications, and cryptographic elements. It was headed by a British Army or RAF officer, usually a major, known as "Special Liaison Officer". The main function of the Liaison Officer or his deputy was to pass Ultra intelligence bulletins to the commander of the command he was attached to, or to other indoctrinated staff officers. In order to safeguard Ultra, special precautions were taken. The standard procedure was for the liaison officer to present the intelligence summary to the recipient, stay with him while he studied it, then take it back and destroy it.
Fixed SLUs existed at the Admiralty, the War Office
War Office
The War Office was a department of the British Government, responsible for the administration of the British Army between the 17th century and 1964, when its functions were transferred to the Ministry of Defence...
, the Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
and at RAF Fighter Command
RAF Fighter Command
RAF Fighter Command was one of three functional commands of the Royal Air Force. It was formed in 1936 to allow more specialised control of fighter aircraft. It served throughout the Second World War, gaining recognition in the Battle of Britain. The Command continued until 17 November 1943, when...
. These units had permanent teleprinter links to Bletchley Park.
Mobile SLUs were attached to field army and air force headquarters, and depended on radio communications to receive intelligence summaries.
The first mobile SLUs appeared during the French campaign of 1940. An SLU supported the British Expeditionary Force
British Expeditionary Force (World War II)
The British Expeditionary Force was the British force in Europe from 1939–1940 during the Second World War. Commanded by General Lord Gort, the BEF constituted one-tenth of the defending Allied force....
(BEF) headed by General Lord Gort
John Vereker, 6th Viscount Gort
Field Marshal John Standish Surtees Prendergast Vereker, 6th Viscount Gort, VC, GCB, CBE, DSO & Two Bars, MVO, MC , was a British and Anglo-Irish soldier. As a young officer in World War I he won the Victoria Cross at the Battle of the Canal du Nord. During the 1930s he served as Chief of the...
. The first liaison officers were Robert Gore-Browne and Humphrey Plowden. A second SLU of the 1940 period was attached to the RAF Advanced Air Striking Force
RAF Advanced Air Striking Force
Before the Second World War it had been agreed between the United Kingdom and France that in case of war, the light bomber force of the Royal Air Force would move to bases within France from which it could operate against targets in Nazi Germany. To achieve this, the RAF Advanced Air Striking Force...
at Meaux
Meaux
Meaux is a commune in the Seine-et-Marne department in the Île-de-France region in the metropolitan area of Paris, France. It is located east-northeast from the center of Paris. Meaux is a sub-prefecture of the department and the seat of an arondissement...
commanded by Air Vice-Marshal P H Lyon Playfair
Patrick Playfair
Air Marshal Sir Patrick Henry Lyon Playfair KBE CB CVO MC RAF was a commander in the Royal Flying Corps during World War I and a senior commander in the Royal Air Force until his retirement during World War II....
. This SLU was commanded by Squadron Leader F.W. "Tubby" Long.
Arthur "Bomber" Harris, officer commanding RAF Bomber Command
RAF Bomber Command
RAF Bomber Command controlled the RAF's bomber forces from 1936 to 1968. During World War II the command destroyed a significant proportion of Nazi Germany's industries and many German cities, and in the 1960s stood at the peak of its postwar military power with the V bombers and a supplemental...
, was not cleared for ULTRA. After D-Day, with the resumption of the strategic bomber campaign over Germany, Harris remained wedded to area bombardment. Historian Frederick Taylor
Frederick Taylor (historian)
Frederick Taylor is a British historian and author of such works as Dresden: Tuesday, February 13, 1945 about the bombing of Dresden in World War II....
argues that, as Harris was not cleared for access to ULTRA, he was given some information gleaned from Enigma but not the information's source. This affected his attitude about post-D-Day directives to target oil installations, since he did not know that senior Allied commanders were using high-level German sources to assess just how much this was hurting the German war effort; thus Harris tended to see the directives to bomb specific oil and munitions targets as a "panacea" (his word) and a distraction from the real task.
Intelligence agencies
In 1940, special arrangements were made within the British intelligence services for handling BONIFACE and later Ultra intelligence. The Security ServiceMI5
The Security Service, commonly known as MI5 , is the United Kingdom's internal counter-intelligence and security agency and is part of its core intelligence machinery alongside the Secret Intelligence Service focused on foreign threats, Government Communications Headquarters and the Defence...
started "Special Research Unit B1(b)" under Herbert Hart. In the SIS this intelligence was handled by "Section V" based at St Albans
St Albans
St Albans is a city in southern Hertfordshire, England, around north of central London, which forms the main urban area of the City and District of St Albans. It is a historic market town, and is now a sought-after dormitory town within the London commuter belt...
.
Radio and cryptography
The communications system was founded by Brigadier Sir Richard Gambier–Parry, who from 1938 to 1946 was head of MI6 Section VIII, based at Whaddon Hall in BuckinghamshireBuckinghamshire
Buckinghamshire is a ceremonial and non-metropolitan home county in South East England. The county town is Aylesbury, the largest town in the ceremonial county is Milton Keynes and largest town in the non-metropolitan county is High Wycombe....
, UK. Ultra summaries from Bletchley Park were sent over landline to the Section VIII radio transmitter at Windy Ridge. From there they were transmitted to the destination SLUs.
The communications element of each SLU was called a "Special Communications Unit" or SCU. Radio transmitters were constructed at Whaddon Hall workshops, while receivers were the National HRO
National HRO
The original National HRO was a 9-tube shortwave general coverage communications receiver manufactured by the National Radio Company of Malden, Massachusetts, USA.-History:...
, made in the USA. The SCUs were highly mobile and the first such units used civilian Packard
Packard
Packard was an American luxury-type automobile marque built by the Packard Motor Car Company of Detroit, Michigan, and later by the Studebaker-Packard Corporation of South Bend, Indiana...
cars. The following SCUs are listed: SCU1 (Whaddon Hall), SCU2 (France before 1940, India), SCU3 (Hanslope Park) SCU5, SCU6 (possibly Algiers and Italy), SCU7 (training unit in the UK), SCU8 (Europe after D-day), SCU9 (Europe after D-day), SCU11 (Palestine and India), SCU12 (India), SCU13 and SCU14.
The cryptographic element of each SLU was supplied by the RAF and was based on the TYPEX
Typex
In the history of cryptography, Typex machines were British cipher machines used from 1937. It was an adaptation of the commercial German Enigma with a number of enhancements that greatly increased its security....
cryptographic machine and one-time pad
One-time pad
In cryptography, the one-time pad is a type of encryption, which has been proven to be impossible to crack if used correctly. Each bit or character from the plaintext is encrypted by a modular addition with a bit or character from a secret random key of the same length as the plaintext, resulting...
systems.
RN Ultra messages from the OIC to ships at sea were necessarily transmitted over normal naval radio circuits and were protected by one-time pad
One-time pad
In cryptography, the one-time pad is a type of encryption, which has been proven to be impossible to crack if used correctly. Each bit or character from the plaintext is encrypted by a modular addition with a bit or character from a secret random key of the same length as the plaintext, resulting...
encryption.
Lucy
An intriguing question concerns the alleged use of Ultra information by the "Lucy" spy ringLucy spy ring
In World War II espionage, the Lucy spy ring was an anti-German operation that was headquartered in Switzerland. It was run by Rudolf Roessler, a German refugee and ostensibly the proprietor of a small publishing firm, Vita Nova...
, headquartered in Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
and apparently operated by one man, Rudolf Roessler
Rudolf Roessler
In World War II espionage, Rudolf Roessler was the central figure in the Lucy spy ring. He was a German refugee who had moved to Switzerland in 1933, and was the proprietor of a small publishing firm in Switzerland, Vita Novi...
. This was an extremely well informed, rapidly responsive ring that was able to get information "directly from German General Staff Headquarters" - often on specific request. It has been alleged that "Lucy" was in major part a conduit for the British to feed Ultra intelligence to the Soviets in a way that made it appear to have come from highly-placed espionage rather than from cryptanalysis
Cryptanalysis
Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...
of German radio traffic. (The Soviets, however, via an agent at Bletchley, John Cairncross
John Cairncross
John Cairncross was a British intelligence officer during World War II, who passed secrets to the Soviet Union...
, knew that Britain had broken Enigma.) The "Lucy" ring was initially treated with suspicion by the Soviets. The information that it provided was accurate and timely, however, and Soviet agents in Switzerland (including their chief, Alexander Radó
Alexander Rado
Alexander Radó, born as Sándor Radó and also known as Alexander Radolfi , was a Hungarian cartographer and a Soviet military intelligence agent in World War II.-Life:...
) eventually learned to take it seriously.
Use of intelligence
Most deciphered messages, often about relative trivia, were not alone sufficient as intelligence reports for military strategists or field commanders. The organisation, interpretation and distribution of intelligence derived from messages from Enigma transmissions and other sources into intelligence was a subtle business. This was not recognised by the Americans before the attack on Pearl HarborAttack on Pearl Harbor
The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...
, but was learnt very quickly afterwards.
At Bletchley Park
Bletchley Park
Bletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
, extensive indexes were kept of the information in the messages decrypted. For each message the traffic analysis recorded the radio frequency, the date and time of intercept, and the preamble—which contained the network-identifying discriminant, the time of origin of the message, the callsign of the originating and receiving stations, and the indicator setting. This allowed cross referencing of a new message with a previous one. The indexes included message preambles, every person, every ship, every unit, every weapon, every technical term and of repeated phrases such as forms of address and other German military jargon that might be usable as cribs
Known-plaintext attack
The known-plaintext attack is an attack model for cryptanalysis where the attacker has samples of both the plaintext , and its encrypted version . These can be used to reveal further secret information such as secret keys and code books...
.
The first decryption of a wartime Enigma message was achieved by the Poles at PC Bruno
PC Bruno
PC Bruno was a Polish-French intelligence station that operated outside Paris during World War II, from October 1939 until June 9, 1940. It decrypted German ciphers, most notably messages enciphered on the Enigma machine.-History:...
on 17 January 1940, albeit one that had been transmitted three months earlier. Little had been achieved by the start of the Allied campaign in Norway in April. At the start of the Battle of France
Battle of France
In the Second World War, the Battle of France was the German invasion of France and the Low Countries, beginning on 10 May 1940, which ended the Phoney War. The battle consisted of two main operations. In the first, Fall Gelb , German armoured units pushed through the Ardennes, to cut off and...
on 10 May 1940, the Germans made a very significant change in the indicator procedures for Enigma messages. However, the Bletchley Park cryptanalysts had anticipated this, and were able—jointly with PC Bruno—to resume breaking messages from 22 May, although often with some delay. The intelligence that these messages yielded was of little operational use in the fast-moving situation of the German advance.
Decryption of Enigma traffic built up gradually during 1940, with the first two prototype bombe
Bombe
The bombe was an electromechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted signals during World War II...
s being delivered in March and August. The traffic was almost entirely limited to Luftwaffe messages. By the peak of the Battle of the Mediterranean
Battle of the Mediterranean
The Battle of the Mediterranean was the name given to the naval campaign fought in the Mediterranean Sea during World War II, from 10 June 1940-2 May 1945....
in 1941, however, Bletchley Park was deciphering daily 2,000 Italian Hagelin messages. By the second half of 1941 30,000 Enigma messages a month were being deciphered, rising to 90,000 a month of Enigma and Fish decrypts combined later in the war.
Some of the contributions that Ultra intelligence made to the Allied successes are given below.
- In April 1940, Ultra information provided a detailed picture of the disposition of the German forces, and then their movement orders for the attack on the Low CountriesLow CountriesThe Low Countries are the historical lands around the low-lying delta of the Rhine, Scheldt, and Meuse rivers, including the modern countries of Belgium, the Netherlands, Luxembourg and parts of northern France and western Germany....
prior to the Battle of FranceBattle of FranceIn the Second World War, the Battle of France was the German invasion of France and the Low Countries, beginning on 10 May 1940, which ended the Phoney War. The battle consisted of two main operations. In the first, Fall Gelb , German armoured units pushed through the Ardennes, to cut off and...
in May.
- An Ultra decrypt of June 1940 read KNICKEBEIN KLEVE IST AUF PUNKT 53 GRAD 24 MINUTEN NORD UND EIN GRAD WEST EINGERICHTET ("The Cleves Knickebein is directed at position 53 degrees 24 minutes north and 1 degree west"). This was the definitive piece of evidence that Dr R V JonesReginald Victor JonesReginald Victor Jones, CH CB CBE FRS, was a British physicist and scientific military intelligence expert who played an important role in the defence of Britain in -Education:...
of scientific intelligence in the Air Ministry needed to show that the Germans were developing a radio guidance system for their bombers. Ultra intelligence then continued to play a vital role in the so-called Battle of the BeamsBattle of the beamsThe Battle of the Beams was a period early in the Second World War when bombers of the German Air Force used a number of increasingly accurate systems of radio navigation for night bombing. British "scientific intelligence" at the Air Ministry fought back with a variety of increasingly effective...
.
- During the Battle of BritainBattle of BritainThe Battle of Britain is the name given to the World War II air campaign waged by the German Air Force against the United Kingdom during the summer and autumn of 1940...
, Air Chief Marshall Sir Hugh DowdingHugh Dowding, 1st Baron DowdingAir Chief Marshal Hugh Caswall Tremenheere Dowding, 1st Baron Dowding GCB, GCVO, CMG was a British officer in the Royal Air Force...
, Commander-in-Chief of RAF Fighter CommandRAF Fighter CommandRAF Fighter Command was one of three functional commands of the Royal Air Force. It was formed in 1936 to allow more specialised control of fighter aircraft. It served throughout the Second World War, gaining recognition in the Battle of Britain. The Command continued until 17 November 1943, when...
, had a teleprinter link from Bletchley ParkBletchley ParkBletchley Park is an estate located in the town of Bletchley, in Buckinghamshire, England, which currently houses the National Museum of Computing...
to his headquarters at RAF Bentley PrioryRAF Bentley PrioryRAF Bentley Priory was a non-flying Royal Air Force station near Stanmore in the London Borough of Harrow. It was famous as the headquarters of Fighter Command during the Battle of Britain and the Second World War. The RAF Bentley Priory site includes a Grade II* listed Officers' Mess and Italian...
for Ultra reports. Ultra intelligence kept him informed of the German strategy, of the strength and location of various Luftwaffe units and often provided advance warning of bombing raids (but not of their specific targets). These contributed to the British success. Dowding was bitterly and sometimes unfairly criticized by others who did not see Ultra, but did not disclose his source.
- Ultra intelligence provided a great deal of information about the Germans' planned Operation Sea Lion to invade England in 1940. Had the invasion been attempted, Britain would have been well prepared.
- An Ultra message reported that equipment at German airfields in Belgium for loading planes with paratroops and their gear was to be dismantled. This was taken as a clear signal that Sea Lion had been cancelled.
- Ultra revealed that a major German air raid was planned for the night of 14 November 1940, and indicated three possible targets, including London and Coventry. However, the specific target was not determined until late on the afternoon of 14 November, by detection of the German radio guidance signals. Unfortunately, countermeasures failed to prevent the devastating Coventry BlitzCoventry BlitzThe Coventry blitz was a series of bombing raids that took place in the English city of Coventry. The city was bombed many times during the Second World War by the German Air Force...
. F. W. Winterbotham claimed that Churchill had advance warning, but intentionally did nothing about the raid, to safeguard Ultra. This claim has been comprehensively refuted by R V Jones, Sir David Hunt, Ralph Bennett and Peter Calvocoressi. Ultra warned of a raid but did not reveal the specific target. Churchill, who had been en route to Ditchley ParkDitchleyDitchley is a country house and estate about northeast of Charlbury in Oxfordshire.-Archaeology:There are remains of a Roman villa on the Ditchley Park estate at Watts Wells, less than southeast of the house...
, was told that London might be bombed, and returned to 10 Downing Street10 Downing Street10 Downing Street, colloquially known in the United Kingdom as "Number 10", is the headquarters of Her Majesty's Government and the official residence and office of the First Lord of the Treasury, who is now always the Prime Minister....
so that he could observe the raid from the Air Ministry roof.
- Ultra intelligence considerably aided the British Army's victory over the much larger Italian army in LibyaLibyaLibya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....
in December 1940-February 1941.
- Ultra intelligence greatly aided the Royal Navy's victory over the Italian navy in the Battle of Cape MatapanBattle of Cape MatapanThe Battle of Cape Matapan was a Second World War naval battle fought from 27–29 March 1941. The cape is on the southwest coast of Greece's Peloponnesian peninsula...
in March 1941.
- Although the Allies lost the Battle of CreteBattle of CreteThe Battle of Crete was a battle during World War II on the Greek island of Crete. It began on the morning of 20 May 1941, when Nazi Germany launched an airborne invasion of Crete under the code-name Unternehmen Merkur...
in May 1941, the Ultra intelligence that a parachute landing was planned meant that heavy losses were inflicted on the Germans and that fewer British troops were captured.
- Ultra intelligence fully revealed the preparations for Operation BarbarossaOperation BarbarossaOperation Barbarossa was the code name for Germany's invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a front., the largest invasion in the history of warfare...
, the German invasion of the USSR. Although this information was passed to the Soviet government, StalinJoseph StalinJoseph Vissarionovich Stalin was the Premier of the Soviet Union from 6 May 1941 to 5 March 1953. He was among the Bolshevik revolutionaries who brought about the October Revolution and had held the position of first General Secretary of the Communist Party of the Soviet Union's Central Committee...
refused to believe it. The information did, however, help British planning, knowing that substantial German forces were to be deployed to the East.
- Ultra intelligence made a very significant contribution in the Battle of the Atlantic. Winston Churchill wrote "The only thing that ever really frightened me during the war was the U-boat peril." The decryption of Enigma signals to the U-boatU-boatU-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
s was much more difficult than those of the Luftwaffe. It was not until June 1941 that Bletchley Park was able to read a significant amount of this traffic currently. Transatlantic convoys were then diverted away from the U-boat "wolfpacks", and U-boat supply vessels sunk. On 1 February 1942, Enigma U-boat traffic became unreadable because of the introduction of a different 4-rotor Enigma machine. This situation persisted until December 1942, although other German naval Enigma messages were still being deciphered, such as those of the U-boat training command at Kiel. From December 1942 to the end of the war, Ultra allowed Allied convoys to evade U-boat patrol lines, and guided Allied anti-submarine forces to the location of U-boats at sea.
- In the Western Desert CampaignWestern Desert CampaignThe Western Desert Campaign, also known as the Desert War, was the initial stage of the North African Campaign during the Second World War. The campaign was heavily influenced by the availability of supplies and transport. The ability of the Allied forces, operating from besieged Malta, to...
, Ultra intelligence helped WavellArchibald Wavell, 1st Earl WavellField Marshal Archibald Percival Wavell, 1st Earl Wavell GCB, GCSI, GCIE, CMG, MC, PC was a British field marshal and the commander of British Army forces in the Middle East during the Second World War. He led British forces to victory over the Italians, only to be defeated by the German army...
and AuchinleckClaude AuchinleckField Marshal Sir Claude John Eyre Auchinleck, GCB, GCIE, CSI, DSO, OBE , nicknamed "The Auk", was a British army commander during World War II. He was a career soldier who spent much of his military career in India, where he developed a love of the country and a lasting affinity for the soldiers...
to prevent Rommel'sErwin RommelErwin Johannes Eugen Rommel , popularly known as the Desert Fox , was a German Field Marshal of World War II. He won the respect of both his own troops and the enemies he fought....
forces from reaching Cairo in the autumn of 1941.
- Ultra intelligence from Hagelin decrypts, and from Luftwaffe and German naval Enigma decrypts, helped sink about half of the ships supplying the Axis in North Africa.
- Ultra intelligence from Abwehr transmissions confirmed that Britain's Security Service (MI5MI5The Security Service, commonly known as MI5 , is the United Kingdom's internal counter-intelligence and security agency and is part of its core intelligence machinery alongside the Secret Intelligence Service focused on foreign threats, Government Communications Headquarters and the Defence...
) had captured all German agents in Britain, and that the Abwehr still believed in the many double agents which MI5 controlled under the Double Cross SystemDouble Cross SystemThe Double Cross System, or XX System, was a World War II anti-espionage and deception operation of the British military intelligence arm, MI5. Nazi agents in Britain - real and false - were captured, turned themselves in or simply announced themselves and were then used by the British to broadcast...
. This enabled major deception operations.
- Deciphered JN-25 messages allowed the U.S. to turn back a Japanese offensive in the Battle of the Coral SeaBattle of the Coral SeaThe Battle of the Coral Sea, fought from 4–8 May 1942, was a major naval battle in the Pacific Theater of World War II between the Imperial Japanese Navy and Allied naval and air forces from the United States and Australia. The battle was the first fleet action in which aircraft carriers engaged...
in April 1942 and set up the decisive American victory at the Battle of MidwayBattle of MidwayThe Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...
in June 1942.
- Ultra contributed very significantly to the monitoring of German developments at PeenemündePeenemündeThe Peenemünde Army Research Center was founded in 1937 as one of five military proving grounds under the Army Weapons Office ....
and the collection of V-1 and V-2 IntelligenceV-1 and V-2 IntelligenceIntelligence on the V-1 and V-2 weapons developed by the Germans for attacks on the United Kingdom during the Second World War was important to countering them...
from 1942 onwards.
- Ultra contributed to Montgomery'sBernard Montgomery, 1st Viscount Montgomery of AlameinField Marshal Bernard Law Montgomery, 1st Viscount Montgomery of Alamein, KG, GCB, DSO, PC , nicknamed "Monty" and the "Spartan General" was a British Army officer. He saw action in the First World War, when he was seriously wounded, and during the Second World War he commanded the 8th Army from...
victory at the Battle of Alam el Halfa by providing warning of Rommel's planned attack.
- Ultra also contributed to the success of Montgomery's offensive in the Second Battle of El AlameinSecond Battle of El AlameinThe Second Battle of El Alamein marked a major turning point in the Western Desert Campaign of the Second World War. The battle took place over 20 days from 23 October – 11 November 1942. The First Battle of El Alamein had stalled the Axis advance. Thereafter, Lieutenant-General Bernard Montgomery...
, by providing him (before the battle) with a complete picture of Axis forces, and (during the battle) with Rommel's own action reports to Germany.
- Ultra provided evidence that the Allied landings in French North Africa (Operation TorchOperation TorchOperation Torch was the British-American invasion of French North Africa in World War II during the North African Campaign, started on 8 November 1942....
) were not anticipated.
- A JN-25 decrypt of 14 April 1943 provided details of Admiral Yamamoto'sIsoroku Yamamotowas a Japanese Naval Marshal General and the commander-in-chief of the Combined Fleet during World War II, a graduate of the Imperial Japanese Naval Academy and a student of Harvard University ....
forthcoming visit to Balalae IslandBalalae IslandBalalae Island is an island of the Shortland Islands Group in the Western Province of the Solomon Islands. The island was the scene of a Japanese atrocity during the Second World War. A work party of 517 British prisoners of war from various artillery regiments captured after the Battle of...
, and on 18 April his aircraft was shot down, killing this man who was regarded as irreplaceable.
- The part played by Ultra intelligence in the preparation for the Allied invasion of SicilyAllied invasion of SicilyThe Allied invasion of Sicily, codenamed Operation Husky, was a major World War II campaign, in which the Allies took Sicily from the Axis . It was a large scale amphibious and airborne operation, followed by six weeks of land combat. It launched the Italian Campaign.Husky began on the night of...
was of unprecedented importance. It provided information as to where the enemy's forces were strongest and that the elaborate strategic deceptions had convinced Hitler and the German high command.
- The success of the Battle of North CapeBattle of North CapeThe Battle of the North Cape was a Second World War naval battle which occurred on 26 December 1943, as part of the Arctic Campaign. The German battlecruiser , on an operation to attack Arctic Convoys of war materiel from the Western Allies to the USSR, was brought to battle and sunk by superior...
, in which HMS Duke of YorkHMS Duke of York (17)HMS Duke of York was a King George V-class battleship of the Royal Navy. Laid down in May 1937, the ship was constructed by John Brown and Company at Clydebank, Scotland, and commissioned into the Royal Navy on 4 November 1941, subsequently seeing service during the Second World War.In...
sank the German battleship ScharnhorstGerman battleship ScharnhorstScharnhorst was a German capital ship, alternatively described as a battleship and battlecruiser, of the German Kriegsmarine. She was the lead ship of her class, which included one other ship, Gneisenau. The ship was built at the Kriegsmarinewerft dockyard in Wilhelmshaven; she was laid down on 15...
, was entirely built on prompt deciphering of German naval signals.
- Both Enigma and Tunny decrypts showed Germany had been taken in by Operation BodyguardOperation BodyguardOperation Bodyguard was the code name for a World War II military deception employed by the Allied nations during the build up to the 1944 invasion of north-western Europe. The aim of the operation was to mislead the German high command as to the exact date and location of the invasion...
, the deception operation to protect Operation OverlordOperation OverlordOperation Overlord was the code name for the Battle of Normandy, the operation that launched the invasion of German-occupied western Europe during World War II by Allied forces. The operation commenced on 6 June 1944 with the Normandy landings...
. They revealled the Germans did not anticipate the Normandy landings and even after D-Day still believed Normandy was only a feint, with the main invasion to be in the Pas de Calais.
- It assisted greatly in Operation CobraOperation CobraOperation Cobra was the codename for an offensive launched by the First United States Army seven weeks after the D-Day landings, during the Normandy Campaign of World War II...
.
- It warned of the major German counterattack at Mortain, and allowed the Allies to surround the forces at FalaiseFalaise pocketThe battle of the Falaise Pocket, fought during the Second World War from 12 to 21 August 1944, was the decisive engagement of the Battle of Normandy...
.
- During the Allied advance to Germany, Ultra often provided detailed tactical information, and showed how Hitler ignored the advice of his generals and insisted on German troops fighting in place 'to the last man'.
Safeguarding of sources
The Allies were seriously concerned with the prospect of the Axis command finding out that they had broken into the Enigma traffic. The British were, it is said, more disciplined about such measures than the Americans, and this difference was a source of friction between them. It was a little bit of a joke that in DelhiDelhi
Delhi , officially National Capital Territory of Delhi , is the largest metropolis by area and the second-largest by population in India, next to Mumbai. It is the eighth largest metropolis in the world by population with 16,753,265 inhabitants in the Territory at the 2011 Census...
, the British Ultra unit was based in a large wooden hut in the grounds of Government House. Security consisted of a wooden table flap across the door with a bell on it and a sergeant sat there. This hut was ignored by all. The American unit was in a large brick building, surrounded by barbed wire and armed patrols. People may not have known what was in there, but they surely knew it was something important and secret.
To disguise the source of the intelligence for the Allied attacks on Axis supply ships bound for North Africa, "spotter" submarines and aircraft were sent to search for Axis ships. These searchers or their radio transmissions were observed by the Axis forces, who concluded their ships were being found by conventional reconnaissance. They suspected that there were some 400 Allied submarines in the Mediterranean and a huge fleet of reconnaissance aircraft on Malta
Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...
. In fact, there were only 25 submarines and at times as few as three aircraft.
This procedure also helped conceal the intelligence source from Allied personnel, who might give away the secret by careless talk, or under interrogation if captured. Along with the search mission that would find the Axis ships, two or three additional search missions would be sent out to other areas, so that crews would not begin to wonder why a single mission found the Axis ships every time.
Other deceptive means were used. On one occasion, a convoy of five ships sailed from Naples
Naples
Naples is a city in Southern Italy, situated on the country's west coast by the Gulf of Naples. Lying between two notable volcanic regions, Mount Vesuvius and the Phlegraean Fields, it is the capital of the region of Campania and of the province of Naples...
to North Africa with essential supplies at a critical moment in the North African fighting. There was no time to have the ships properly spotted beforehand. The decision to attack solely on Ultra intelligence went directly to Churchill. The ships were all sunk by an attack "out of the blue", arousing German suspicions of a security breach.
To distract the Germans from the idea of a signals breach (such as Ultra), the Allies sent a radio message to a fictitious spy in Naples, congratulating him for this success. According to some sources the Germans decrypted this message and believed it.
In the Battle of the Atlantic, the precautions were taken to the extreme. In most cases where the Allies knew from intercepts the location of a U-boat in mid-Atlantic, the U-boat was not attacked immediately, until a "cover story" could be arranged. For example a search plane might be "fortunate enough" to sight the U-boat, thus explaining the Allied attack.
Some Germans had suspicions that all was not right with Enigma. Admiral Karl Dönitz
Karl Dönitz
Karl Dönitz was a German naval commander during World War II. He started his career in the German Navy during World War I. In 1918, while he was in command of , the submarine was sunk by British forces and Dönitz was taken prisoner...
received reports of "impossible" encounters between U-boats and enemy vessels which made him suspect some compromise of his communications. In one instance, three U-boats met at a tiny island in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, and a British destroyer promptly showed up. The U-boats escaped and reported what had happened. Dönitz immediately asked for a review of Enigma's security. The analysis suggested that the signals problem, if there was one, was not due to the Enigma itself. Dönitz had the settings book changed anyway, blacking out Bletchley Park for a period. However, the evidence was never enough to truly convince him that Naval Enigma was being read by the Allies. The more so, since B-Dienst
B-Dienst
The B-Dienst was a German naval codebreaking organisation. During World War II, B-Dienst solved British Naval Cypher No. 3, providing intelligence for the Battle of the Atlantic, until the British Admiralty introduced Naval Cypher No. 5 on 10 June 1943. B-Dienst also solved a number of merchant...
, his own codebreaking group, had partially broken Royal Navy traffic (including its convoy codes early in the war), and supplied enough information to support the idea that the Allies were unable to read Naval Enigma.
By 1945 most German Enigma traffic could be decrypted within a day or two, yet the Germans remained confident of its security. Had they known better, they could have changed systems, forcing Allied cryptanalysts to start over.
Post-war disclosures
While it is obvious why Britain and the U.S. went to considerable pains to keep Ultra a secret until the end of the war, it has been a matter of some conjecture why Ultra was kept officially secret for 29 years thereafter, until 1974. During that period the important contributions to the war effort of a great many people remained unknown, and they were unable to share in the glory of what is likely one of the chief reasons the Allies won the war - or, at least, as quickly as they did.At least three versions exist as to why Ultra was kept secret so long. Each has plausibility, and all may be true. First, as David Kahn pointed out in his 1974 New York Times review of Winterbotham's The Ultra Secret, after World War II the British gathered up all the Enigma machines they could find and sold them to Third World countries, confident that they could continue reading the messages of the machines' new owners.
A second explanation relates to a misadventure of Churchill between the World Wars, when he publicly disclosed information from decrypted Soviet communications. This had prompted the Soviets to change their ciphers, leading to a blackout. The third explanation is given by Winterbotham, who recounts that two weeks after V-E Day, on 25 May 1945, Churchill requested that former recipients of Ultra intelligence not divulge the source or the information that they had received from it, in order that there be neither damage to the future operations of the Secret Service nor any cause for the Axis to blame Ultra for their defeat.
Since it was British and, later, American message-breaking which had been the most extensive, this meant that the importance of Enigma decrypts to the prosecution of the war remained unknown. Discussion by either the Poles or the French of Enigma breaks carried out early in the war would have been uninformed regarding breaks carried out during the balance of the war. Nevertheless, the 1973 public disclosure of Enigma decryption in the book Enigma by French intelligence officer Gustave Bertrand
Gustave Bertrand
Gustave Bertrand was a French military intelligence officer who made a vital contribution to the decryption, by Poland's Cipher Bureau, of German Enigma ciphers, beginning in December 1932...
generated pressure to discuss the rest of the Enigma–Ultra story.
The British ban was finally lifted in 1974, the year that a key participant on the distribution side of the Ultra project, F. W. Winterbotham
F. W. Winterbotham
Frederick William Winterbotham was a British Royal Air Force officer who during World War II supervised the distribution of Ultra intelligence. Later, Winterbotham published the first popular account of Ultra....
, published The Ultra Secret.
The official history of British intelligence in World War II was published in five volumes from 1979 to 1988. It was chiefly edited by Harry Hinsley, with one volume by Michael Howard. There is also a one-volume collection of reminiscences by Ultra veterans, Codebreakers (1993), edited by Hinsley and Alan Stripp.
After the war, surplus Enigmas and Enigma-like machines were sold to many countries around the world, which remained convinced of the security of the remarkable cipher machines. Their traffic was not so secure as they believed, however, which is one reason the British and Americans made the machines available. Switzerland even developed its own version of Enigma, known as NEMA
NEMA (machine)
In the history of cryptography, the NEMA , also designated the T-D , was a 10-wheel rotor machine designed by the Swiss Army during World War II as a replacement for their Enigma machines.-History:The Swiss became aware that their current machine, a commercial Enigma , had been broken by...
, and used it into the late 1970s.
Some information about Enigma decryption did get out earlier, however. In 1967, Polish military historian Władysław Kozaczuk in his book Bitwa o tajemnice ("Battle for Secrets") first revealed Enigma had been broken by Polish cryptologists before World War II. The same year, David Kahn in The Codebreakers
The Codebreakers
The Codebreakers – The Story of Secret Writing is a book by David Kahn, published in 1967 comprehensively chronicling the history of cryptography from ancient Egypt to the time of its writing...
described the 1944 capture of a Naval Enigma machine from U-505 and mentioned, somewhat in passing, Enigma messages were already being read by that time, requiring "machines that filled several buildings."
Ladislas Farago
Ladislas Farago
Ladislas Farago was a military historian and journalist who published a number of best-selling books on history and espionage, especially concerning the World War II era....
's 1971 best-seller The Game of the Foxes gave an early garbled version of the myth of the purloined Enigma. According to Farago, it was thanks to a "Polish-Swedish ring [that] the British obtained a working model of the 'Enigma' machine, which the Germans used to encipher their top-secret messages." "It was to pick up one of these machines that Commander Denniston went clandestinely to a secluded Polish castle [!] on the eve of the war. Dilly Knox later solved its keying, exposing all Abwehr signals encoded by this system." "In 1941 [t]he brilliant cryptologist Dillwyn Knox, working at the Government Code & Cypher School at the Bletchley center of British code-cracking, solved the keying of the Abwehr's Enigma machine."
By 1970, newer, computer-based ciphers were becoming popular as the world increasingly turned to computerised communications, and the usefulness of Enigma copies (and rotor machines generally) rapidly decreased. It was shortly after this, in 1974, a decision was taken to permit revelations about some Bletchley Park operations.
The United States National Security Agency
National Security Agency
The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States Department of Defense responsible for the collection and analysis of foreign communications and foreign signals intelligence, as well as protecting U.S...
(NSA) retired the last of its rotor-based encryption systems, the KL-7
KL-7
The TSEC/KL-7, code named ADONIS and POLLUX, was an off-line non-reciprocal rotor encryption machine. The KL-7 had eight rotors to encrypt the text, seven of which moved in a complex pattern, controlled by notched rings. The non-moving rotor was in fourth from the left of the stack. The encrypted...
series, in the 1980s.
Postwar consequences
There has been controversy about the influence of Allied Enigma decryption on the course of World War II. It has also been suggested that the question should be broadened to include Ultra's influence not only on the war itself, but also on the post-war period.F. W. Winterbotham, the first author to outline the influence of Enigma decryption on the course of World War II, likewise made the earliest contribution to an appreciation of Ultra's postwar influence, which now continues into the 21st Century — and not only in the postwar establishment of Britain's GCHQ (Government Communication Headquarters) and America's NSA. "Let no one be fooled," Winterbotham admonishes in chapter 3, "by the spate of television films and propaganda which has made the war seem like some great triumphant epic. It was, in fact, a very narrow shave, and the reader may like to ponder [...] whether [...] we might have won [without] Ultra."
Debate continues on whether, had postwar political and military leaders been aware of Ultra's role in Allied victory in World War II, these leaders might have been less optimistic about post-World War II military involvements.
Knightley
Phillip Knightley
Phillip Knightley is a journalist, critic, and non-fiction author, visiting Professor of Journalism at the University of Lincoln, England, and media commentator on the intelligence services and propaganda.-Biography:...
suggests that Ultra may have contributed to the development of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
. The Soviets received disguised Ultra information, but the existence of Ultra itself was not disclosed by the western Allies. The Soviets, who had clues to Ultra's existence, possibly through Kim Philby
Kim Philby
Harold Adrian Russell "Kim" Philby was a high-ranking member of British intelligence who worked as a spy for and later defected to the Soviet Union...
and Anthony Blunt
Anthony Blunt
Anthony Frederick Blunt , was a British art historian who was exposed as a Soviet spy late in his life.Blunt was Professor of the History of Art at the University of London, director of the Courtauld Institute of Art, Surveyor of the King's Pictures and London...
, may thus have felt still more distrustful of their wartime partners.
The mystery surrounding the discovery of the sunk U-869 off the coast of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
by divers Richie Kohler
Richie kohler
Richie Kohler is an experienced technical wreck diver and shipwreck historian who has been diving and exploring shipwrecks since 1980. Together with John Chatterton, Kohler was one of the co-hosts of the television series Deep Sea Detectives on the History Channel and is also a consultant for the...
and John Chatterton
John Chatterton
John Chatterton is one of the world’s most accomplished and well known wreck divers. Together with Richie Kohler, he was one of the co-hosts for the History Channel’s Deep Sea Detectives where they have completed work on 57 episodes of this successful series...
was unraveled in part through the analysis of Ultra intercepts, which demonstrated that, although U-869 had been ordered by U-boat Command to change course and proceed to north Africa, near Rabat, the submarine had missed the messages changing her assignment and had continued to the eastern coast of the U.S., her original destination.
See also
- Hut 6Hut 6Hut 6 was a wartime section of Bletchley Park tasked with the solution of German Army and Air Force Enigma machine ciphers. Hut 8, by contrast, attacked Naval Enigma...
- Hut 8Hut 8Hut 8 was a section at Bletchley Park tasked with solving German naval Enigma messages. The section was led initially by Alan Turing...
- Magic (cryptography)Magic (cryptography)Magic was an Allied cryptanalysis project during World War II. It involved the United States Army's Signals Intelligence Section and the United States Navy's Communication Special Unit. -Codebreaking:...
- Military intelligenceMilitary intelligenceMilitary intelligence is a military discipline that exploits a number of information collection and analysis approaches to provide guidance and direction to commanders in support of their decisions....
- Signals intelligence in modern historySignals intelligence in modern historySIGINT is a contraction of SIGnals INTelligence. Before the development of radar and other electronics techniques, signals intelligence and communications intelligence were essentially synonymous...