Review of Herivelismus and the German Military Enigma by John Herivel

Abstract

Herivel, John; Herivelismus and the German Military Enigma. M&M Baldwin, 24 High Street, Cleobury Mortimer, Kidderminster DY14 8BY, England, 2008. ISBN: 978-0-947712-46-4. Softcover: £9 [postage UK and US surface mail £2: US via airmail £4]. This slim, 144-page, book is an invaluable addition to the voluminous coverage by countless writers of varying levels of knowledge and believability that have written on the subject of Enigma, and the successful attacks upon that system by Allied codebreakers during World War Two. John Herivel is to be found at the top end of a roll call of those authors: he was there. Early in the year following the outbreak of World War Two, in January 1940, the author was a mathematics undergraduate at Cambridge whence he was recruited for Britain’s cryptologic establishment, the Government Code and Cipher School [GC&CS]—the expanding intelligence operation at Bletchley Park [BP]—by his former Cambridge tutor, Gordon Welchman. Within months of his arrival Herivel’s insight into not only the Enigma machine employed by the Wehrmacht for its secret, high-level communications but also into the psychology of the Enigma operator, resulted in a unique form of attack against the formidable German cryptographic system: the Herivel Tip. . .but more about that later in this review. What might today be known as ‘‘outside the box’’ thinking as employed by BP’s cryptanalysts is also exemplified by and attributed to another of the BP ‘‘greats,’’ Dillwyn ‘‘Dilly’’ Knox, who is said to have asked prospective codebreakers ‘‘Which way does a clock turn?’’ If his respondent came back with ‘‘Clockwise of course’’ Knox countered with ‘‘Not if you’re the clock’’. . .perhaps it is such unorthodox and roundabout thinking that separates the merely first-class codebreaker from the genius! Herivel gives a brief dedication to a number of individuals that includes Dilly Knox; the Polish mathematicians led by Marian Rejewski, who broke the German military Enigma in 1932; Gordon Welchman; Gustave Bertrand of French Intelligence; and, curiously, German cipher official Hans Thilo Schmidt who, from his position within the German codebreaking establishment, supplied vital and secret information to Bertrand. He begins his narrative with a short Preface and then looks at the development of Enigma in the years following World War I. A brief discussion of the background to the Polish attack on the German military Enigma follows. Next, he includes a short chapter that covers nicely the ‘‘Franco-German Alliance,’’ which describes the involvement of the renegade German official Hans