Anglo-American Intelligence Partnership in WWII

Excerpt for Application Consideration
Dissertation Submitted to the London School of Economics by Krystal Norman
“A Question of Deference: A Study of the British Superiority in the Anglo-American Special Intelligence Gathering
Relationship through the Second World War.”
Submitted: September 2015
CHAPTER 2:
The Second World War, MAGIC,
ULTRA and the BRUSA Agreement
As the interwar war period drew to a close and the advent of the Second World War drew
nearer, the Anglo-American partnership that had cooled down significantly started to take a much
more warm and urgent tone as both partners began to recognise the insipient threat that both
Germany and a possible fifth column (e.g. subversive) could pose to the Allied powers1. The
Second World War proved to be perhaps the grandest example of a crisis-driven opportunity for
the Anglo-American intelligence partnership to flourish, and it did so with gusto (hence the
suggestion of the historiography that the genesis of the intelligence occurred at this time, and not
earlier). The leadership in place in both nations at the time was crucial to the success of the
partnership, as both Winston Churchill (the British Prime Minister) and Franklin Delano Roosevelt
(the American President) exhibited a close enough working relationship that encouraged at least a
cursory amount of efficacy as the war got started. The leaders were very similar in that they were
in agreement that a partnership was in fact necessary at the outset of the war; this mutual desire
expressed itself ultimately in the Atlantic Charter, a policy agreement arrived upon between the
United States and the United Kingdom in August of 1941 that jointly stated the post-war aims of
the Allied powers, relying heavily on the rhetoric of espousing freedom and peace and additional
common aims of the Allies2. The Atlantic Charter, while an agreement based in rhetorical policy
rather than intelligence objectives, served as a de facto basis for the subsequent intelligence
gathering agreements (official and unofficial) forged between the United States and the United
Kingdom.
In terms of intelligence gathering, the United States was still playing catch up with its more
experienced British cousins; taking a page from Churchill’s book, Roosevelt moved to coordinate
the American intelligence services in an attempt to streamline intelligence operations. In June of
1939 he created the Interdepartmental Intelligence Committee (IIC), meant to coordinate the
efforts of the Federal Bureau of Investigation (FBI), the Military Information Division (MID), and the
ONI. While the intentions behind its creation were noble, the IIC proved to be little more than a
vehicle with which to pass about existing information3—a far cry from the practiced efficiency of
the British intelligence services at this time, culminating with their infamous decipher of the Enigma
codes.
Contemporaneously with the British Enigma breakthrough however came Roosevelt’s
continued recognition (especially considering the war had now been ongoing for two years) that
the American intelligence apparatus needed vast and continual improvement. In 1941 he created
the Office of the Coordinator of Information (COI), which had been suggested by William J.
Donovan (and intelligence officer who had travelled to Great Britain as an informal emissary). The
COI would was a centralised intelligence unit that would venture to combine the concentrations of
collection, analysis and operations, organised in the operational style and tradition of the British
intelligence apparatus, as Donovan was familiar with it from his time as an emissary and thought it
beneficial to the operations of the United States (much like Pershing before him during World War
I). As the reorganisation was his brainchild as it were, Roosevelt saw fit to make Donovan the
1 Smith, Bradley F., The ULTRA-MAGIC Deals and the Most Secret Special Relationship 1940-1946 (Novato, CA,
1993), pp. 10-1.
2
Morton, H.V., Atlantic Meeting: An Account of Mr. Churchill’s Voyage in H.M.S. Prince of Wales, in August 1941, and
the Conference with President Roosevelt Which Resulted in the Atlantic Charter (London, 1943) pp. 129-131.
3 Lowenthal, Mark M., United States Intelligence: Evolution and Anatomy (Washington, D.C.: Center for Strategic
and International Studies, 1992), p. 7.

inaugural COI4. With the British crack of the German Enigma codes in March of 1941(it should be
noted that the Polish were the first to come close to deciphering Enigma in the 1930s and
subsequently passed on their findings plus replicas of the machine to the British and French in
1939), the Anglo-American intelligence sharing partnership finally started to take the definitive
shape that would carry it through the remainder of the war and into the second half of the twentieth
century.
MAGIC and ULTRA
Despite the Polish progress made on Enigma at the outset of the war, there was a
prevailing thought that Enigma was ‘unbreakable;’ it did in fact confound the cryptanalysts at
Bletchley Park (some of the most prominent in the world) for several years before it finally
achieved full deciphering in 1941. The move toward cooperation between the two countries
however came one year prior, in the immediate aftermath of the fall of France when there were
comprehensive discussions on the sharing of Japanese cipher information5 (this initial request was
initiated by the British, as the majority of their efforts at GC&CS were centred on German and
Italian ciphers6). The initial request from the British to the American Naval attaché in June of 1940
was rebuffed by the Americans, however a subsequent appeal to President Roosevelt was met
with an approval. In the successive discussions of ‘standardisation of arms’ between the
Americans (namely Brigadier General George V. Strong representing the U.S. Army) and the
British Chiefs of Staff, the Americans suggested in no uncertain terms a bold new direction in
terms of the existing intelligence partnership: a free exchange of intelligence7. The British were
sceptical and indeed trepidatious to engage in such a free flowing exchange of information at this
time (especially when it came to the progress they were making at GC&CS regarding Germany
and Italy), as they keenly remembered when the Americans sent over Herbert Yardley (an
American cryptologist) to work with the newly created eighth section of military intelligence in
Britain (MI8) during the First World War and he wrote a book detailing his experiences a mere
twelve after the war ended8. Considering the British tendency to have had ironclad controls on its
security and intelligence measures, such openness a prior “free exchange of information” would
not be welcomed again. The British trepidation extended up through the ranks in 1940 (before
ULTRA), all the way to the Prime Minister; concerned about the possibility of sensitive information
‘flying about’ Churchill instructed his subordinates to provide the Americans with the bare minimum
of required information and pad the remainder of the documents9. This decision to be play
Britain’s cards close to its chest even in regard to relations with the United States is clear evidence
that it was keenly aware that in the realm of intelligence there was a distinct British advantage (or
conversely an American handicap) that the British would exploit while it could. There were some in
British leadership that recognised that holding back some information could equate to playing a
dangerous game with the Anglo-American relationship (an important overall status that the British
tended to hold dear), one gentleman even going so far as to suggest to Churchill in a response to
memo concerning secure information ‘flying about’ that Britain may be unable to fully secure
United States cooperation unless it acts with full frankness as far as the United States was
4 Ibid., pp. 7-8.
5 Personal Letter to the Director, Ref# 2836, 15 November, 1940, Detailing discussion with SOE regarding US
concerns about reserved sharing of Italian and German decrypts in return for open exchange of Japanese
decrypts, HW 14/8, TNA.
6 Butler (US) to Hopkinson (UK), Ref# 2914, 5 November, 1940, U.S. requesting full informational exchange re.
German and Italian ciphers, pointing out in was Britain who initiated the initial request, HW 14/8, TNA.
7
Alvarez, David J. Allied and Axis Signals Intelligence in World War II (London; Portland, OR, 1999) pp. 119-120.
8 Personal Letter to the Director, Ref# 2836, 15 November, 1940, Detailing discussion with SOE regarding US
concerns about reserved sharing of Italian and German decrypts in return for open exchange of Japanese
decrypts, HW 14/8, TNA.
9 Churchill to Bridges, (memo), 22 November 1940, Instructions to provide Americans with bare
minimum info, CAB 120/744 TNA.

concerned10. The desire to avoid creating a feeling of suspicion or distrust is echoed11 throughout
the run up to the BRUSA Agreement in 194312, however in terms of intelligence it should not be
read as a British admission of American superiority; the British desire to avoid creating an air of
distrust between itself and the Americans is born out of the maintenance of self-interest and the
overarching war aims, not a deference to American intelligence prowess (of which it still had little
at this time, outside of its participation in partnerships).
Despite its overarching lackadaisical attitude toward intelligence in the run up to the war
and the diminutive size of its cryptanalytic branch, the Signals Intelligence Service (SIS), the
United States was still able to make some strides in regard to the crucial sphere of Japanese
cables (exclusively; there was no attempts made at Japanese military radio traffic, never mind
German Enigma traffic; that was clearly the province of the British). In 1940 American
cryptanalysts were able to get recreate the newest machine cipher that the Japanese government
had released the year prior (dubbed ‘Purple’ by the SIS) and were able to were able to decipher its
cipher in October of that year. All intelligence garnered from the duplicated Purple machine was
codenamed ‘MAGIC’ by the SIS, and proved to be a valuable bargaining chip in the discussions of
intelligence sharing with the British for a country whose intelligence successes with slim to nil in
the years prior13. It stands to reason that it is for this very reason that the Americans felt
emboldened enough to request a full exchange in the face of Britain’s insistence upon an embargo
on ‘unreserved’ exchange of German and Italian ciphers and point out that it was in fact the British
that came to the Americans for a change14. It is ironic and unfortunate however that while the
Americans experienced some strides in the cryptanalytic field in regard to the Japanese ciphers, it
still did not anticipate the Japanese attack Pearl Harbour, and the failure to do so remains one of
the biggest American intelligence failures in recorded history. The exact mechanics of the Pearl
Harbour attack aside, the American amateur-like take on intelligence without the guiding hand of
the British was simply not as effective against existential threat; proving further the British superior
position in intelligence gathering. Additionally, while it is in fact true that the British initiated the first
request for MAGIC exchange, it can be argued based on historical evidence of the cooperative
relationship during the First World War that the British training of American analysts throughout
1917 and 1918 contributed significantly to American cryptanalytic skill and therefore success in the
field, and without it MAGIC may not have been so easily achievable. This line of reasoning is also
compatible with the argument that British superiority was a constant thread all throughout the
Anglo-American intelligence relationship, even when the Americans appeared to have the upper
hand (such as in the case of MAGIC).
While the Americans found some measure of success with MAGIC, the British reached the
zenith of cryptanalytic fortitude when they were finally able to decipher the ever elusive German
Enigma machine ciphers. Apparently having learned its lesson after the failure of encryption in its
10 Ismay to Churchill, (memo), 12 December 1940, Response to instructions regarding info to
Americans, suggestion of frankness with Americans to ensure cooperation, CAB 120/744 TNA.
11 Memo, ‘Special Intelligence and the Americans’, 1940, Statement that it would soon become clear
to the Americans that Britain was in possession of proprietary info which may create hurt feelings,
HW 69/9 TNA.
12 War Cabinet Joint Planning Staff, ‘Information for the United States’, 30 April 1941, quoting Halifax
when stating that considering that much of the future course of the war would be determined by Washington if
and when the U.S. entered the war, and therefore an air of frankness should be Maintained, CAB 122/14
TNA.
13 Smith, Bradley F., The ULTRA-MAGIC Deals and the Most Secret Special Relationship 1940-1946 (Novato, CA,
1993), pp. 34-5.
14 Butler (US) to Hopkinson (UK), Ref# 2914, 5 November, 1940, U.S. requesting full informational exchange
re. German and Italian ciphers, pointing out in was Britain who initiated the initial request, HW 14/8, TNA.

communications during the First World War (the Zimmermann Telegram being a prime example of
such an oversight), Germany sought to upgrade their encryption prowess and invented the
Enigma machine in 191815. Using rotors that changed settings often (eventually daily), the
machine was highly effective in the encrypting the German ciphers, and was seen as an almost
insurmountable challenge. Having spent the majority of the interwar period sharpening its edge in
the field of cryptanalytics, the centre of GC&CS’ cryptanalysis operations at Bletchley Park (known
only as ‘BP’ to employees forbidden to refer to it by name by Denniston due to the nature of its
work and the incredibly tight level of security the British assigned to its intelligence operations16)
had recruited a team of highly effective cryptanalysts and mathematicians to work under
Commander Alistair Denniston (the operational head of GC&CS since the end of World War I
through 1942), including such cryptanalytic heavy hitters as John Tiltman, Nigel de Grey and the
infamous Dr. Alan Turing. Since the Polish had extended their knowledge of Enigma to the British
and French in 1939, cracking the Enigma ciphers had been the ultimate goal of the GC&CS. Using
a three-pronged angle of attack, using three main attributes as a measure of study for potential
weaknesses. First, the regular intake of German signals received daily; second, study of the
mechanical workings of the machine itself; and third, while rote in nature perhaps the most
important, the element of organisation and procedure (something the British had proven very
effective at in terms of intelligence gathering). A constant routine of the aforementioned three-
pronged attack consumed Bletchley daily, until a breakthrough finally came in April of 1941 when
the first Enigma ciphers were decrypted17. Very quickly after the first decipher the British moved to
re-code any ‘special intelligence’ as ‘ULTRA18,’ and made quick work of creating a hard and fast
set of rules and regulations regarding the handling, distribution and analysis of ULTRA material
(before the United States was even brought into the fold)19 Group Captain F. W. Winterbotham
(the man in charge of the dissemination of ULTRA materials who reported directly to ‘C,’ or the
head of MI6 Stewart Menzies) touched on the seriousness of the ULTRA regulations in his
memoirs: among other things, there was a strict limiting on who would see ULTRA material, no
recipient was to transmit or repeat an ULTRA signal, and no recipient of ULTRA material was to
voluntarily place themselves in a position where he could be captured by enemy forces20.
Alongside the British advances in regard to Enigma, the United States had (after its initial foray
into cooperation on the Japanese cipher front) decided that further cooperation was both
warranted and mutually beneficial, while Britain remained sceptical (note the scepticism was on
the intelligence sharing front; this dissertation makes no arguments regarding the military or
tactical desires of either country at this time). In 1941 the United States first made suggestions
regarding the training of American personnel “if and when the U.S. entered the war21” (it would
enter the war in December of 1941 after the attack on Pearl Harbour) and continued its push for a
full exchange with a request for Far East info collaboration22; as a measure of its trepidation,
Britain agreed to the ‘full’ exchange in name only; it set several exceptions such as a ban on
15
Lewin, Ronald, ULTRA Goes to War: The Secret Story (London, 1978), pp. 25-7.
16 Memo from Commander A. Denniston, Doc# 2, 25 November 1940, No mention of
Bletchley/Park in correspondence, HW 14/8 TNA.
17 Lewin, Ronald, ULTRA Goes to War: The Secret Story (London, 1978), pp. 58-61.
18 Winterbotham to de Grey (memo), Doc# 217, 14 July 1942, Information on re-coding ‘special’ to ‘
ULTRA’, HW 14/43 TNA.
19 Winterbotham to Jones (memo), Doc# 262, 17 July 1942, Coordinated routing instructions
ULTRA transmits, HW 14/43 TNA.
20
Winterbotham, F. W., The ULTRA Secret (London, 1974), p. 89.
21 Stark (Chief of US Naval Ops) to Ghormley (Special Naval Ops London) (memo), 4 April 1941,
Instructions on how to observe operations in London and discussion of potential American
Training, ADM 1/18895 TNA.
22 Eden to Halifax (memo), Ref# 696, 13 June 1941, US proposes full exchange on Far East, UK
UK agrees with some exceptions, CAB 122/1030 TNA.

exchange of SIS sources, order of battle (as America had not entered the war yet), and SOE
organisational policy. Again, British officials made pains to address the Americans with ‘frankness,’
but they were unwilling to disclose everything without first receiving special authenticity. 23
While British authorities had since the inception of ULTRA decided to release only certain
pieces of ULTRA information to the Americans as they saw fit, they eventually decided that it was
beneficial for the war effort to bring the Americans under the ULTRA umbrella, British concerns
about American security measures being too loose be damned. In 1942 General Dwight D.
Eisenhower (Supreme Allied Commander of European Forces) and his staff were briefed on
ULTRA materials and given a detailed list of access and security measures24.
Several months passed with Eisenhower making decisions on the European front using his
access to the ULTRA information that his colleagues back in the United States did not have, which
created a disparity of information, proving not to be beneficial to the war effort. In September and
October of 1942, there were several memos circulated amongst the British intelligence committee
regarding how best to go about training the American personnel (first, there would be a
comprehensive five-week training course for all incoming personnel25; second, the insistence that
Americans should be trained in London by experienced personnel, not with training materials sent
to the States 26).
The iron fist that the British exhibited over both the security of ULTRA information as well as
the dissemination, use and access to it was a marvel; additionally interesting was the clear
American deference to it, even while American authorities expressed (sometimes quite loudly)
their dislike of certain policies (one personal letter from a British official in 1943 explicitly mentions
how “most cooperative” the Americans were and that they were willing to “fall in” with all of
Britain’s wishes27. It was this explicit submission to Britain that is indicative of the continued
balance of power between the United States and United Kingdom in the realm of intelligence at
this time; irrespective of what was happening in other areas of international relations, in terms of
the Anglo-American partnership, Britain continued to hold the advantage over the Americans, to
phrase it in a competitive sense. The cooperative relationship remained strong however, so much
so that belligerent parties began to not only notice it but discuss it in their diplomatic cables. In
1942 (after the initial American successes with MAGIC and the partnership with Britain on the Far
East cables), the Japanese minister stationed in Madrid expressed concern at the level of
tightening cooperation between the United States and the United Kingdom, fearing that they were
planning a joint counterattack on Japan after the Pearl Harbour surprise attack in 194128. Despite
difficulties and an inherent advantage on the side of the British, it appeared to outside parties that
the partnership was a well-oiled machine; such an appearance was fortuitous for the Allies indeed.
23 Cornwall-Jones to Coleridge (memo), Doc# 1714B/5, 6 July 1941, Instruction that future operations
not be disclosed to Americans, CAB 122/14 TNA.
24 Memo from Brigadier Gen. Harris, Ref# 552. 28 August 1942, Regarding Y Board Review of Special
Special Intelligence access/security measures to Eisenhower staff, HW 69/9 TNA.
25 Nicholls (Chairman of Y Committee) memo, Ref# MI8/2177, 19 October 1942,
Incoming U.S. personnel be trained in London, HW 69/9 TNA.
26 Memo, Ref# MI8/2635, Training Course for Americans, details five week training
course for American personnel, HW 69/9 TNA.
27 Wilson to Dill (personal letter), Doc# 6C, 5 January 1943, US resentment of
restriction on troop movements, CAB 122/14 TNA.
28 Japanese Minister (Madrid) to Japan Foreign Minister (Tokyo), (memo), Ref# 1037, 4 October 1942,
Expressing concern over US/UK co-op, HW 1/951 TNA.

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