1st ed., 1979. 305 pp., 17 maps + 5 figures. D.j., 24 x 15cm. Spine of d.j., a little faded o/w Nr.FINE. Ultra, played a vital role in the victory of World War II. What effect did the decoding of German wireless traffic at Bletchley Park have on the fighting? In this book the author reconstructs for the first time the campaign for the liberation of Europe from the 25,000 or more signals which were based on Bletchley decodes. At every point from the Normandy landings to the German surrender eleven months later, this book offers a unique, and in places controversial, analysis. A former member of the staff at Bletchley Park, the author brings a remarkable blend of detailed inside knowledge and meticulous historical judgement to this classic military history.