David Kahn

ADDRESS: 120 Wooleys Lane, Great Neck NY 11023 USA.

ABSTRACT: A list of important events in the making and breaking of the German Enigma cipher machine of World War II is given in the order of their occurrences.

KEYWORDS: Enigma, chronology.

In view of the importance of ULTRA to the history of intelligence, and in view of the errors in dating that appear in so many accounts, I thought it would be worthwhile to establish a list of important dates in the story of the Enigma cipher machine and its solution. Most deal with the naval machine.

This chronology comes mainly from my book, Seizing the Enigma (New York: Houghton Mifflin, 1991), which is based as much as possible on primary or on solid secondary sources, chiefly F. H. Hinsley et al's magisterial History of British Intelligence in the Second World War (Cambridge: Cambridge University Press, 1979 1988). For my book, the Naval Historical Branch in London made available to me a key primary source for much naval dating, but I promised not to cite it by name, a promise that I am honoring. Information about the times of naval solution comes from analyses of intercepts in the Public Record Office, London, and in the National Archives, Washington. To avoid burdening this list with a heavy biographical apparatus, I have given as sources the page numbers in Hinsley or in Seizing the Enigma that specify these dates or detail those incidents. Notes in the form 2:...