Ernst Constantin Fetterlein (3 April 1873Victor Madeira, "`Because I Don't Trust Him, We are Friends': Signals Intelligence and the Reluctant Anglo-Soviet Embrace, 1917-24", ''Intelligence & National Security'' 19(1), March 2004, pp. 29–51. – June 1944Ralph Erskine

to

Intelligence Forum Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be des ...

, 11 October 2004) was a

Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...

cryptographer Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

who later defected to Britain. Fetterlein was born in

St Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...

, the son of Karl Fedorovich Fetterlein, a German-language tutor, and Olga Fetterlein, née Meier. He studied a variety of eastern languages at the University of St Petersburg, graduating in 1894. On 25 November 1896 he joined the Ministry of Foreign Affairs. He eventually became the chief cryptologist for the Tsar of Russia,Stephen Budiansky, ''Battle of Wits'', 2000, , p. 56 holding the rank of "General-Admiral," an honorary title in Tsarist Russia.Michael Smith, "GC&CS and the First Cold War", pp. 1-40 in ''Action This Day'', 2001, During

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, he was known for a time as Ernst Popov as his German-derived name could have drawn unwanted attention. Amongst others, he solved German, Austrian and British codes. Upon the Russian Revolution of 1917, he fled to Western Europe with his wife on board a Swedish ship, narrowly evading capture. He contacted the British and French intelligence organisations, offering to work for whoever would pay him the most, which was apparently the British, as he was recruited to

Room 40 Room 40, also known as 40 O.B. (old building; officially part of NID25), was the cryptanalysis section of the British Admiralty during the First World War. The group, which was formed in October 1914, began when Rear-Admiral Henry Oliver, the ...

in June 1918 to work on

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, Austrian and Bolshevik codes. After the end of World War I, he worked for the successor to Room 40, the Government Code and Cypher School (GC&CS), becoming a senior assistant on 17 December 1919. During this time he worked on Soviet Communist traffic. He was thought well of by his colleagues, one of whom wrote, "He was a brilliant cryptographer. On book cipher and anything else where insight was vital he was quite the best. He was a fine linguist and would usually get an answer no matter the language." He retired in 1938. His brother, P. K. Fetterlein, also worked for GC&CS. Fetterlein came out of retirement during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

to assist GC&CS's diplomatic section at Berkeley Street. He worked on "

Floradora "Floradora", also called Keyword, was a doubly enciphered diplomatic code used by the Germans during the Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 193 ...

", a German diplomatic code.Budiansky, 2000, p. 219

References

{{DEFAULTSORT:Fetterlein, Ernst Russian cryptographers British cryptographers 1873 births 1944 deaths Foreign Office personnel of World War II