Dilly Knox

Alfred Dillwyn "Dilly" Knox, CMG (23 July 1884 – 27 February 1943) was an English classics scholar and papyrologist at King's College, Cambridge and a codebreaker. As a member of the Room 40 codebreaking unit he helped decrypt the Zimmermann Telegram which brought the USA into the First World War.<ref name="Gannon 2011">Template:Harvnb</ref> He then joined the Government Code and Cypher School (GC&CS).<ref name="codebreaker.italian_enigma">Template:Harvnb</ref>

As chief cryptographer,<ref name ="codebreaker.italian_enigma"/> Knox played an important role in the Polish–French–British meetings on the eve of the Second World War which disclosed Polish cryptanalysis of the Axis Enigma to the Allies.<ref name="copeland.colossus.smith"/>

At Bletchley Park, he worked on the cryptanalysis of Enigma ciphers until his death in 1943. He built the team and discovered the method that broke the Italian Naval Enigma, producing the intelligence credited with Allied victory at the Battle of Cape Matapan. In 1941, Knox broke the Abwehr Enigma.<ref name='batey.enigmas.xi'>Template:Harvnb</ref> By the end of the war, Intelligence Service Knox had disseminated 140,800 Abwehr decrypts,<ref name='batey.enigmas.xi'/> including intelligence important for D-Day.<ref name='telegraph.obituary' />

Personal life and family

Dillwyn Knox, the fourth of six children,<ref name="odnb">Template:Harvnb</ref> was the son of Edmund Knox, tutor at Merton College and later Bishop of Manchester; he was the brother of E. V. Knox, Wilfred Knox, Ronald Knox,<ref name="odnb"/> Ethel Knox, and Winifred Peck,<ref name=who>"Peck, Winifred Frances, (Lady Peck)", Who Was Who, online edition, Oxford University Press, 2014, retrieved 9 May 2014 Template:Subscription required</ref> and uncle of the novelist Penelope Fitzgerald.<ref name='fitzgerald.knox'>Template:Harvnb</ref> His father was a descendant of John Arbuthnott, 8th Viscount of Arbuthnott.<ref>Dod's Peerage, Baronetage and Knightage of Great Britain and Ireland, Sampson Low, Marston & Co., 1904, p. 983</ref><ref>The Spectator, vol. 20, 1847, p. 1171</ref><ref>The Gentleman's Magazine, vol. 177, 1845, p. 311</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Dillwyn—known as "Dilly"—Knox was educated at Summer Fields School, Oxford, and then Eton College.<ref name="odnb"/> He studied classics at King's College, Cambridge from 1903,<ref name=Classics>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and in 1909 was elected a Fellow<ref name="odnb"/> following the death of Walter Headlam, from whom he inherited extensive research into the works of Herodas. While an undergraduate he was friends with Lytton Strachey and John Maynard Keynes. He and Keynes were lovers at Eton.<ref name=Supermac>Template:Harvnb</ref> Knox privately coached Harold Macmillan, the future Prime Minister, at King's for a few weeks in 1910, but Macmillan found him "austere and uncongenial".<ref name=Classics/>

He married Olive Rodman in 1920, forgetting to invite two of his three brothers to his wedding.<ref name='batey.enigmas.xii'>Template:Harvnb</ref> The couple had two sons, Oliver and Christopher.Template:Fact

He was an atheist.Template:Efn

Academic scholarship

Between the two World Wars Knox worked on the great commentary on Herodas that had been started by Walter Headlam, damaging his eyesight while studying the British Museum's collection of papyrus fragments, but finally managing to decipher the text of the Herodas papyri. The Knox-Headlam edition of Herodas finally appeared in 1922.<ref>Template:Citation</ref>

Codebreaking

First World War

Soon after war broke out in 1914,<ref name="codebreaker.italian_enigma"/> Knox was recruited to the Royal Navy's cryptological effort in Room 40 of the Admiralty Old Building,<ref>Template:Harvnb</ref> where some of his work was done in the bath. He persuaded his superiors to have a bathtub installed in his office in the cryptanalysis section of the British Admiralty<ref>Template:Cite book</ref> (in Room 53).<ref name="codebreaker.pre-war"/> In 1917, Knox followed Room 40 with its expansion into ID25.<ref name="codebreaker.italian_enigma"/>

Among other tasks, he was involved in breaking:

• the Zimmermann Telegram, which contributed to bringing the USA into the war.<ref name="Gannon 2011"/>
• much of the German admiral's flag code by exploiting an operator's love of romantic poetry.<ref name ="codebreaker.italian_enigma"/>

Between the wars

Government Code and Cypher School

Template:Rquote During the First World War he had been elected Librarian at King's College, but never took up the appointment. After the war Knox intended to resume his research at King's, but was persuaded by his wife to remain at his secret work; indeed, so secret was this work that his own children had no idea, until many years after his death, what he did for a living, and his contribution to the war effort.<ref name=Classics/>

Commercial Enigma

The Enigma machine became available commercially in the 1920s. In Vienna in 1925,<ref name="codebreaker.hugh_foss">Template:Harvnb</ref> Knox bought the Enigma 'C' machine evaluated by Hugh Foss in 1927 on behalf of GC&CS. Foss found "a high degree of security" but wrote a secret paper describing how to attack the machine if cribs – short sections of plain text – could be guessed.<ref name="copeland.colossus.smith">Template:Harvnb</ref> When – a decade later – Knox picked up this work, he developed a more effective algebraic system (rodding) based on the principles described by Foss.<ref name="codebreaker.hugh_foss"/>

Spanish Enigma

The Germany Navy ({{#invoke:Lang|lang}}) adopted Enigma in 1926, adding a plug-board ({{#invoke:Lang|lang}}) to improve security. Nazi Germany supplied non-{{#invoke:Lang|lang}}ed machines to Franco's Nationalists in the Spanish Civil War. On 24 April 1937, Knox broke the Spanish Enigma but knowledge of this breakthrough was not shared with the Republicans.<ref name="copeland.colossus.smith"/>Template:Efn Soon afterwards, Knox began to attack signals between Spain and Germany encrypted using {{#invoke:Lang|lang}}ed Enigma machines.<ref name="copeland.colossus.smith"/>

On the eve of the Second World War

Polish–French–British meetings

GC&CS began to discuss Enigma with the French {{#invoke:Lang|lang}} in 1938, obtaining from the Bureau details of Wehrmacht Enigma supplied by Asché and signal intercepts, some of which must have been made in Eastern Europe. This led the French to disclose their links with the {{#invoke:Lang|lang}} (Polish cryptographers).<ref name="copeland.colossus.smith"/> Knox, Hugh Foss and Alastair Denniston represented the GC&CS at the first Polish–French–British meeting at Paris in January 1939.<ref name="codebreaker.italian_enigma"/> The Poles were under order to disclose nothing of importance, leaving the British codebreakers disappointed. Knox's description of his system of rodding impressed the Polish codebreakers and they requested his presence at a second meeting.<ref name="copeland.colossus.smith"/>

Knox attended the second Polish–French–British conference, held on 25–26 July 1939 at the Polish Cipher Bureau (at Pyry, south of Warsaw, Poland). The Poles began to disclose to their French and British allies their achievements in solving Enigma decryption.<ref name="Budiansky">Template:Harvnb</ref>

Although Marian Rejewski, the Polish cryptographer and mathematician who solved the plugboard-equipped Enigma used by Nazi Germany, approached the problem through permutation theory (whereas Knox applied linguistics), a good personal relationship was quickly established at the conference. The good impression made by Rejewski on Knox played an important role in increasing recruitment of mathematicians to Bletchley Park.<ref name ="codebreaker.italian_enigma"/> Knox was chagrined — but grateful — to learn how simple was the solution of the Enigma's entry ring (standard alphabetical order).<ref name="Budiansky"/>

After the meeting, he sent the Polish cryptologists a very gracious note in Polish, on official British government stationery, thanking them for their assistance and sending "sincere thanks for your cooperation and patience".<ref name="codebreaker.italian_enigma"/> Enclosed were a beautiful scarf featuring a picture of a Derby winner and a set of paper 'batons'.<ref name="Budiansky"/>

These 'batons' were known as rods to the British and had been used to solve the Spanish Enigma. Knox's rodding method was later used to break the Italian Naval Enigma.<ref name="codebreaker.italian_enigma"/>

Turing's bombe

Alan Turing worked on Enigma during the months leading to the outbreak of the Second World War in September 1939, and occasionally visited GC&CS's London HQ to discuss this problem with Knox. In the 1939 register Turing was recorded in Naphill, staying with Knox and his wife. By November 1939 Turing had completed the design of the bombe — a radical improvement of the Polish bomba.<ref name=codebreaker.copeland>Template:Harvnb</ref>

Second World War

Knox's rodding method

To break non-{{#invoke:Lang|lang}}ed Enigma machines (those without a plugboard), Knox (building on earlier research by Hugh Foss) developed a system known as 'rodding', a linguistic as opposed to mathematical way of breaking codes.<ref name="copeland.colossus.smith"/> This technique worked on the Enigma used by the {{#invoke:Lang|lang}} (Italian Navy) and the German {{#invoke:Lang|lang}}.<ref>Template:Harvnb</ref> Knox worked in 'the Cottage', next door to the Bletchley Park mansion, as head of a research section, which contributed significantly to cryptanalysis of the Enigma.<ref name="odnb"/>

Knox's team at The Cottage used rodding to decrypt intercepted Italian naval signals describing the sailing of an Italian battle fleet, leading to the Battle of Cape Matapan in March 1941. Admiral John Godfrey, Director of Naval Intelligence credited the Allied victory at Matapan to this intelligence; Admiral Sir Andrew Cunningham, who had commanded the victorious fleet at Matapan, went to Bletchley to congratulate 'Dilly and his girls'.<ref name="codebreaker.italian_enigma"/>

Intelligence Services Knox

In October 1941, Knox solved the {{#invoke:Lang|lang}} Enigma.<ref name='batey.enigmas.xi'/>, although nothing was known about the machine itself.<ref name="bletchleypark1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Intelligence Services Knox (ISK) was established to decrypt {{#invoke:Lang|lang}} communications.<ref name='batey.enigmas.xi'/> In early 1942, with Knox seriously ill, Peter Twinn took charge of running ISK and was appointed head after Knox's death.<ref name='telegraph.obituary'>Template:Harvnb</ref><ref name='batey.enigmas.xi'/> By the end of the war, ISK had decrypted and disseminated 140,800 messages.<ref name='batey.enigmas.xi'/> Intelligence gained from these {{#invoke:Lang|lang}} decrypts played an important part in ensuring the success of the Double-Cross System of MI5 and MI6, and in Operation Fortitude, the Allied campaign to deceive the Germans about D-Day.<ref name='telegraph.obituary' />

Death

Knox's work was cut short when he fell ill with lymphoma.<ref>Template:Harvnb</ref> When he became unable to travel to Bletchley Park, he continued his cryptographic work from his home in Hughenden, Buckinghamshire, where he received the CMG.<ref name="fitz249250">Template:Harvnb</ref> He died on 27 February 1943.<ref name="fitz249250"/> A biography of Knox, written by Mavis Batey, one of 'Dilly's girls', the female codebreakers who worked with him, was published in September 2009.<ref>Template:Harvnb</ref>

Classified poetry

Knox celebrated the victory at Battle of Cape Matapan with poetry, which remained classified until 1978.<ref name="codebreaker.italian_enigma"/>

References

Works cited

• Template:Cite book (Updated and extended version of Action This Day: From Breaking of the Enigma Code to the Birth of the Modern Computer Bantam Press 2001)
• Template:Cite ODNB
• Template:Citation
• Template:Cite book
• Template:Cite book (Updated and extended version of Action This Day: From Breaking of the Enigma Code to the Birth of the Modern Computer Bantam Press 2001)
• Template:Citation
• Template:Citation
• Template:Cite book (Updated and extended version of Action This Day: From Breaking of the Enigma Code to the Birth of the Modern Computer Bantam Press 2001)
• Template:Cite book (Updated and extended version of Action This Day: From Breaking of the Enigma Code to the Birth of the Modern Computer Bantam Press 2001)
• Template:Cite book
• Template:Citation
• {{#invoke:citation/CS1|citation

|CitationClass=web }}

• Template:Citation
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• Template:Citation
• Template:Cite book
• Template:Citation
• Template:Cite book

External links

• Description of rodding at Frode Weierud’s CryptoCellar