Hinsley, historian and himself a participant at Bletchley, was an inspired choice for writing this official history, for which he and his colleagues have been given unrestricted access to all government papers. This book, part one of the third volume, covers the period from mid-1943 to the eve of D-Day. It depicts how British intelligence gained knowledge of German dispositions in the Sicilian campaign, and in the air and sea war, and above all reconstructs British efforts to interpret scattered clues concerning German rocketry and the preparation of V-1 and V-2 bombs. Hinsley is also very good on how Britain finally decided to back Tito and break with Mihailovic, despite the reluctance of the Foreign Ministry. Intelligence gathering and interpretation were complex enough; the tactical, command, and political use of the evidence is another part of the story, and inevitably, failures and human rivalries came into play. Adopting Flaubert's recipe, "pas de monstres, et pas de héros," Hinsley is scrupulously fair but forthright, and this book, as indeed the whole series, constitutes a triumphant achievement: an enviable task admirably executed.