Ultra

Ultra secret ULTRA Special Liaison Unit interceptsadvancesBletchley ParkBoniface (cover name)British code-breakerscracked Germany's codesdeciphering of German signals traffic
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 (GC&CS) at Bletchley Park.wikipedia
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Bletchley Park

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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 (GC&CS) at Bletchley Park.
According to the official historian of British Intelligence, the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and without it the outcome of the war would have been uncertain.

Enigma machine

EnigmaEnigma codeEnigma cipher machine
Much of the German cipher traffic was encrypted on the Enigma machine. "Enigma" refers to a family of electro-mechanical rotor cipher machines.
As used in practice, the Enigma encryption proved vulnerable to cryptanalytic attacks by Germany's adversaries, at first Polish and French intelligence and, later, a massive effort mounted by the United Kingdom at Bletchley Park as part of the Ultra program.

Cryptanalysis of the Enigma

EnigmaEnigma decryptsAbwehr Enigma
The term "Ultra" has often been used almost synonymously with "Enigma decrypts".
This yielded military intelligence which, along with that from other decrypted Axis radio and teleprinter transmissions, was given the codename Ultra.

F. W. Winterbotham

Frederick WinterbothamF.W. WinterbothamFrederick William Winterbotham
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.
Frederick William Winterbotham (16 April 1897 – 28 January 1990) was a British Royal Air Force officer (latterly a Group Captain) who during World War II supervised the distribution of Ultra intelligence.

Rotor machine

rotor cipher machinerotorrotor cipher machines
"Enigma" refers to a family of electro-mechanical rotor cipher machines.
The most famous example is the German Enigma machine, whose messages were deciphered by the Allies during World War II, producing intelligence code-named Ultra.

Signals intelligence

SIGINTELINTelectronic intelligence
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 (GC&CS) at Bletchley Park.
The combined effort of intercepts and cryptanalysis for the whole of the British forces in World War II came under the code name "Ultra" managed from Government Code and Cypher School at Bletchley Park.

Alan Turing

TuringAlan M. TuringAlan Mathison Turing
At Bletchley Park, some of the key people responsible for success against Enigma included mathematicians Alan Turing and Hugh Alexander and, at the British Tabulating Machine Company, chief engineer Harold Keen.
During the Second World War, Turing worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain's codebreaking centre that produced Ultra intelligence.

Lorenz cipher

TunnyLorenz SZ 40/42Lorenz
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.
The deciphered Lorenz messages made one of the most significant contributions to British Ultra military intelligence and to Allied victory in Europe, due to the high-level strategic nature of the information that was gained from Lorenz decrypts.

Biuro Szyfrów

Cipher BureauPolish Cipher BureauBiuro Szyfrow
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 good luck.
This Polish intelligence-and-technology transfer would give the Allies an unprecedented advantage (Ultra) in their ultimately victorious prosecution of World War II.

Fish (cryptography)

FishFish cyphersFish cipher
In June 1941, the Germans started to introduce on-line stream cipher teleprinter systems for strategic point-to-point radio links, to which the British gave the code-name Fish.
Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies.

Stewart Menzies

Sir Stewart MenziesStewart Graham MenziesBrigadier Sir Stewart Menzies
Winston Churchill was reported to have told King George VI, when presenting to him Stewart Menzies (head of the Secret Intelligence Service and the person who controlled distribution of Ultra decrypts to the government): "It is thanks to the secret weapon of General Menzies, put into use on all the fronts, that we won the war!"
By distributing the Ultra material collected by the Government Code & Cypher School, for the first time, MI6 became an important branch of the government.

Secret Intelligence Service

MI6SISBritish Secret Service
Winston Churchill was reported to have told King George VI, when presenting to him Stewart Menzies (head of the Secret Intelligence Service and the person who controlled distribution of Ultra decrypts to the government): "It is thanks to the secret weapon of General Menzies, put into use on all the fronts, that we won the war!"
The intelligence gleaned from this source, codenamed "Ultra" by the British, was a substantial aid to the Allied war effort.

John Cairncross

The Soviets, however, through an agent at Bletchley, John Cairncross, knew that Britain had broken Enigma.
In 1942 and 1943 Cairncross worked in GC&CS, Bletchley Park on ULTRA ciphers.

Battle of Cape Matapan

Cape MatapanMatapanBattle of Matapan
In late March 1941, as British ships of the Mediterranean Fleet covered troop movements to Greece, Mavis Batey, a cryptographer at Bletchley Park, made a breakthrough, reading the Italian naval Enigma for the first time.

MI5

Security ServiceBritish Security ServiceSecurity Service (MI5)
The Security Service started "Special Research Unit B1(b)" under Herbert Hart.
With the ending of the Battle of Britain and the abandonment of invasion plans (correctly reported by both SIS and the Bletchley Park Ultra project), the spy scare eased, and the internment policy was gradually reversed.

Cryptanalysis

cryptanalystcodebreakingcodebreaker
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.
'Ultra' intelligence has been credited with everything between shortening the end of the European war by up to two years, to determining the eventual result.

Battle of Alam el Halfa

Battle of Alam HalfaAlam el HalfaAlam Halfa
Montgomery knew of Axis intentions through Ultra signals intercepts and left a gap in the southern sector of the front, knowing that Rommel planned to attack there and deployed the bulk of his armour and artillery around Alam el Halfa Ridge, 20 mi behind the front.

Magic (cryptography)

Magic MAGIC American cryptographers
The U.S. used the codename Magic for its decrypts from Japanese sources, including the "Purple" cipher.

Battle of Crete

Creteinvasion of CreteOperation Mercury
On 22 April, the HQ in Crete was ordered to burn all material received through the Ultra link, but Churchill ruled that the information must still be provided.

Richard Gambier-Parry

Brigadier Sir Richard Gambier-ParryBrigadier Sir Richard Gambier-Parry, KCMG
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 Buckinghamshire, UK.
That facility served in a number of capacities, the most critical the sending of Ultra intelligence from Bletchley Park to officers in the field.

Second Battle of El Alamein

El AlameinBattle of El AlameinSecond Battles of El Alamein
The British had an intelligence advantage because Ultra and local sources exposed the Axis order of battle, its supply position and intentions.

Battle of the Beams

KnickebeinX-GerätY-Gerät
Winston Churchill had also been given Ultra intelligence from decrypted Enigma messages that mentioned 'bombing beams'.

Erwin Rommel

RommelField Marshal RommelGeneral Rommel
This thrust was not anticipated by the British, who had Ultra intelligence showing that Rommel had orders to remain on the defensive until at least May, when the 15th Panzer Division were due to arrive.

Battle of Britain

Britainair battle with GermanyBattle of Britain Day
Ultra, the information obtained from Enigma intercepts, gave the highest echelons of the British command a view of German intentions.

Battle of the Mediterranean

MediterraneanMediterranean CampaignMediterranean theatre
By the peak of the Battle of the Mediterranean in 1941, however, Bletchley Park was deciphering daily 2,000 Italian Hagelin messages.
The decisive factors in the Allied victory were the effectiveness of aircraft carriers, the use of Ultra intercepts and the lack of radar on the Italian ships.