Editing Signals intelligence (section)

==History==
===Origins===
{{Main|Signals intelligence in modern history}}
Electronic interceptions appeared as early as 1900, during the [[Boer War]] of 1899–1902. The British [[Royal Navy]] had installed wireless sets produced by [[Marconi]] on board their ships in the late 1890s, and the [[British Army]] used some limited wireless signalling. The [[Boers]] captured some wireless sets and used them to make vital transmissions.<ref>{{Cite journal|last=Chapman|first=J.W.M.|date=2002|title=British Use of 'Dirty Tricks' in External Policy Prior to 1914|url=https://www.jstor.org/stable/26014122|journal=War in History|volume=9|issue=1|pages=60–81|doi=10.1191/0968344502wh244oa|jstor=26014122|s2cid=159777408|issn=0968-3445|url-access=subscription}}</ref> Since the British were the only people transmitting at the time, the British did not need special interpretation of the signals that they were.<ref name=Lee>Compare: {{cite web
|last= Lee
|first= Bartholomew
|title= Radio Spies – Episodes in the Ether Wars
|url= http://www.trft.org/TRFTPix/spies9eR2006.pdf
|access-date= 8 October 2007
|quote= As early as 1900 in the Boer War, the Royal Navy in South Africa appears to have used wireless sets inherited from the Royal Engineers to signal from the neutral port of Lourenco Marques 'information relative to the enemy' albeit in violation of international law. [...] This first use of radio for intelligence purposes depended, of course, on the inability of others to intercept the signals, but in 1900, only the British in that part of the world had any wireless capability.
|archive-date= 27 February 2008
|archive-url= https://web.archive.org/web/20080227075207/http://www.trft.org/TRFTPix/spies9eR2006.pdf
|url-status= dead
}}</ref>

The birth of signals intelligence in a modern sense dates from the [[Russo-Japanese War]] of 1904–1905. As the Russian fleet prepared for conflict with Japan in 1904, the British ship [[HMS Diana (1895)|HMS ''Diana'']] stationed in the [[Suez Canal]] intercepted Russian naval wireless signals being sent out for the mobilization of the fleet, for the first time in history.<ref>
''Report from HMS Diana on Russian Signals intercepted at Suez'', 28 January 1904, Naval library, Ministry of Defence, London.
</ref>{{Ambiguous|date=February 2024|reason=What event/side was the first in history?}}

===Development in World War I===
[[File:Ztel2.jpg|thumb|[[Zimmermann Telegram]], as decoded by [[Room 40]] in 1917]]
Over the course of the [[First World War]], a new method of signals intelligence reached maturity.<ref name="Wheeler">{{cite journal|author=Douglas L. Wheeler|title=A Guide to the History of Intelligence 1800–1918|journal=Journal of U.S. Intelligence Studies|url=http://www.afio.com/publications/Wheeler_Hist_of_Intel_1800-1918_in_AFIO_INTEL_WinterSprg2012.pdf}}</ref> Russia’s failure to properly protect its communications fatally compromised the [[Russian Army]]’s [[Russian invasion of East Prussia (1914)|advance early in World War I]] and led to their disastrous defeat by the Germans under [[Erich Ludendorff|Ludendorff]] and [[Paul von Hindenburg|Hindenburg]] at the [[Battle of Tannenberg]]. In 1918, French intercept personnel captured a message written in the new [[ADFGVX cipher]], which was cryptanalyzed by [[Georges Painvin]]. This gave the Allies advance warning of the German 1918 [[German spring offensive|Spring Offensive]].

The British in particular, built up great expertise in the newly emerging field of signals intelligence and codebreaking (synonymous with cryptanalysis). On the declaration of war, Britain cut all German undersea cables.<ref>{{cite journal |last=Winkler |first=Jonathan Reed |date=July 2009 |journal=The Journal of Military History |title=Information Warfare in World War I |volume=73 |issue=3 |pages=845–867 |doi=10.1353/jmh.0.0324|s2cid=201749182 }}</ref> This forced the Germans to communicate exclusively via either (A) a telegraph line that connected through the British network and thus could be tapped; or (B) through radio which the British could then intercept.<ref name="Beesly">{{cite book |title=Room 40: British Naval Intelligence, 1914–1918 |last=Beesly |first=Patrick |year=1982 |publisher=Hamish Hamilton Ltd |location=Long Acre, London |isbn=0-241-10864-0}}</ref> Rear Admiral [[Henry Oliver]] appointed [[James Alfred Ewing|Sir Alfred Ewing]] to establish an interception and decryption service at the [[Admiralty (United Kingdom)|Admiralty]]; [[Room 40]].<ref name="Beesly" /> An interception service known as [[Y-stations|'Y' service]], together with the [[General Post Office|post office]] and [[Marconi]] stations, grew rapidly to the point where the British could intercept almost all official German messages.<ref name="Beesly" />

The German fleet was in the habit each day of wirelessing the exact position of each ship and giving regular position reports when at sea. It was possible to build up a precise picture of the normal operation of the [[High Seas Fleet]], to infer from the routes they chose where defensive minefields had been placed and where it was safe for ships to operate. Whenever a change to the normal pattern was seen, it immediately signalled that some operation was about to take place, and a warning could be given. Detailed information about submarine movements was also available.<ref name="Beesly" />

The use of radio-receiving equipment to pinpoint the location of any single transmitter was also developed during the war. Captain [[H.J. Round]], working for [[Marconi]], began carrying out experiments with [[direction finding|direction-finding]] radio equipment for [[British Expeditionary Force (World War I)|the army in France]] in 1915. By May 1915, the Admiralty was able to track German submarines crossing the North Sea. Some of these stations also acted as 'Y' stations to collect German messages, but a new section was created within Room 40 to plot the positions of ships from the directional reports.<ref name="Beesly" />

Room 40 played an important role in several naval engagements during the war, notably in detecting major German sorties into the [[North Sea]]. The [[Battle of Dogger Bank (1915)|battle of Dogger Bank]] was won in no small part due to the intercepts that allowed the Navy to position its ships in the right place.<ref>Livesey, Anthony, Historical Atlas of World War One, Holt; New York, 1994 p. 64</ref> It played a vital role in subsequent naval clashes, including at the [[Battle of Jutland]] as the British fleet was sent out to intercept them. The direction-finding capability allowed for the tracking and location of German ships, submarines, and [[Zeppelin]]s. The system was so successful that by the end of the war, over 80 million words, comprising the totality of German wireless transmission over the course of the war, had been intercepted by the operators of the [[Y-stations]] and decrypted.<ref>{{cite web|url=http://marconiheritage.org/ww1-intel.html|title=Code Breaking and Wireless Intercepts}}</ref> However, its most astonishing success was in [[cryptanalysis|decrypting]] the [[Zimmermann Telegram]], a [[telegram]] from the German Foreign Office sent via Washington to its [[ambassador]] [[Heinrich von Eckardt]] in Mexico.

===Postwar consolidation===
With the importance of interception and decryption firmly established by the wartime experience, countries established permanent agencies dedicated to this task in the interwar period. In 1919, the British Cabinet's Secret Service Committee, chaired by [[Lord Curzon]], recommended that a peace-time codebreaking agency should be created.<ref name="johnson">{{cite book |first=John |last=Johnson |title=The Evolution of British Sigint: 1653–1939 |year=1997 |publisher=HMSO |asin=B002ALSXTC|page=44}}</ref> The [[Government Code and Cypher School]] (GC&CS) was the first peace-time codebreaking agency, with a public function "to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision", but also with a secret directive to "study the methods of cypher communications used by foreign powers".<ref>{{cite book |first=Michael |last=Smith |chapter=GC&CS and the First Cold War |title=Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer |editor1-first=Michael |editor1-last=Smith |editor2-first=Ralph| editor2-last=Erskine |publisher=Bantam Press |year=2001 |isbn=978-0-593-04910-5|pages=16–17}}</ref> GC&CS officially formed on 1 November 1919, and produced its first decrypt on 19 October.<ref name="johnson" /><ref>{{cite book|first=Paul|last=Gannon|title=Inside Room 40: The Codebreakers of World War I|publisher=Ian Allan Publishing |year=2011 |isbn=978-0-7110-3408-2}}</ref> By 1940, GC&CS was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems.<ref>David Alvarez, GC&CS and American Diplomatic Cryptanalysis</ref>

The [[Black Chamber|US Cipher Bureau]] was established in 1919 and achieved some success at the [[Washington Naval Conference]] in 1921, through cryptanalysis by [[Herbert Yardley]]. Secretary of War [[Henry L. Stimson]] closed the US Cipher Bureau in 1929 with the words "Gentlemen do not read each other's mail."

===World War II===
[[File:Colossus.jpg|thumbnail|left|A Mark 2 [[Colossus computer]]. The ten Colossi were the world's first programmable electronic computers, and were built to break the German codes.]]
The use of SIGINT had even greater implications during [[World War II]]. The combined effort of intercepts and cryptanalysis for the whole of the British forces in World War II came under the code name "[[Ultra (cryptography)|Ultra]]", managed from [[Government Code and Cypher School]] at [[Bletchley Park]]. Properly used, the German [[Enigma machine|Enigma]] and [[Lorenz cipher]]s should have been virtually unbreakable, but flaws in German cryptographic procedures, and poor discipline among the personnel carrying them out, created vulnerabilities which made Bletchley's attacks feasible.

Bletchley's work was essential to defeating the [[U-boat]]s in the [[Battle of the Atlantic]], and to the British naval victories in the [[Battle of Cape Matapan]] and the [[Battle of North Cape]]. In 1941, Ultra exerted a powerful effect on the [[North African campaign|North African desert campaign]] against German forces under General [[Erwin Rommel]]. General Sir [[Claude Auchinleck]] wrote that were it not for Ultra, "Rommel would have certainly got through to Cairo". Ultra decrypts featured prominently in the story of [[Operation Salam|Operation SALAM]], [[László Almásy]]'s mission across [[Western Desert (Egypt)|the desert]] behind Allied lines in 1942.<ref>Gross, Kuno, Michael Rolke and András Zboray, [http://fjexpeditions.com/resources/salam/operation_salam.htm Operation SALAM] – László Almásy's most daring Mission in the Desert War, Belleville, München, 2013</ref> Prior to the [[Normandy landings]] on D-Day in June 1944, the Allies knew the locations of all but two of Germany's fifty-eight [[Western Front (World War II)|Western Front]] divisions.

[[Winston Churchill]] was reported to have told King [[George VI]]: "It is thanks to the secret weapon of General [[Stewart Menzies|Menzies]], put into use on all the fronts, that we won the war!" Supreme Allied Commander, [[Dwight D. Eisenhower]], at the end of the war, described Ultra as having been "decisive" to Allied victory.<ref>{{citation |last=Winterbotham |first=F. W. |author-link=F. W. Winterbotham |title=The Ultra Secret |location=New York |publisher=Harper & Row |year=1974 |isbn=0-06-014678-8|pages=154, 191 }}</ref> Official historian of British Intelligence in World War II [[Harry Hinsley|Sir Harry Hinsley]] argued that Ultra shortened the war "by not less than two years and probably by four years"; and that, in the absence of Ultra, it is uncertain how the war would have ended.<ref>{{citation |last=Hinsley |first=Sir Harry |author-link=Harry Hinsley |title=The Influence of ULTRA in the Second World War |orig-year=1993 |year=1996 |url=http://www.cdpa.co.uk/UoP/HoC/Lectures/HoC_08e.PDF |access-date=23 July 2012}}</ref>

At a lower level, German cryptanalysis, direction finding, and traffic analysis were vital to Rommel's early successes in the [[Western Desert campaign|Western Desert Campaign]] until British forces tightened their communications discipline and Australian raiders destroyed his principal SIGINT Company.<ref>{{Cite web |last=P9-J |date=2015-08-08 |title=German SIGINT in the Desert Campaign |url=https://friendsintelligencemuseum.org/2015/08/08/german-sigint-in-the-desert-campaign/ |access-date=2023-12-05 |website=Friends of the Intelligence Corps Museum |language=en-GB}}</ref>
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