This book is an edition of the General Report on Tunny with commentary that clarifies the often difficult language of the GRT and fitting it into a variety of contexts arising out of several separate but intersecting story lines, some only implicit in the GRT. Explores the likely roots of the ideas entering into the Tunny cryptanalysis Includes examples of original worksheets, and printouts of the Tunny-breaking process in action Presents additional commentary, biographies, glossaries, essays, and bibliographies