This history is intended for the layman. Our work has been traditionally incomprehensible -- the last distinguished visitor I remember had barely sat down before he announced that he was not a mathematician and did not expect to understand anything - and anyone wishing to probe the more abstruse mathematical aspect of it should turn to the technical volume which is being compiled in collaboration with Hut 6. In fact there is nothing very difficult to understand in the work we did, although it was confusing at first sight, and I have attempted to explain only the basic principles involved in the methods we used. As a result of this I hope that anyone interested in Hut 8 and willing to read the semi-technical passages with some care will get a fairly clear idea of our work and I make no excuse for having deliberately avoided mentioning many of the complications which arose - thus when describing the machine I say that after pressing the keys 26 x 26 x 26 times the machine has returned to its starting place but the mathematician will realize that the introduction of wheels 6, 7 and 8 with 2 turnovers each is liable to split this cycle into several smaller cycles.
The book starts with a description of the machine and the methods of sending messages and is followed by some information as to where the machine was used and the volume of traffic carried. After these tedious but rather necessary pages of background it follows the course of events more or less chronologically, starting some time before the war. Certain subjects -- like Banburismus or Offizier - required whole sections to themselves outside the historical narrative and these are the subjects of a series of digressions: the problem of Offizier, for instance, is dealt with after mentioning the first Offizier break in October 1941 and from then onwards it is hardly necessary to refer to Offizier which changed comparatively little and was broken regularly. This method tends to make the early part of the book a series of rather disconnected chapters but greatly simplifies the last 1½ years of the story when events moved rapidly and progress with a variety of different keys had to be described.
/s/ HUT 8