ADDED: see my other comment, sometimes it gets bogged down in detail for non-specialists, or discusses intrinsically boring theaters, but much of it is riveting, and you sort of need to read the whole account, e.g. the story of Juan Pujol García AKA GARBO (https://en.wikipedia.org/wiki/Juan_Pujol_Garc%C3%ADa) starts very early in the war, when in Spain, on his very own after his offers to help were rejected by the British and Americans, he started running his own deception operation and got accepted as a German agent. Per Wikipedia:
He was instructed to travel to Britain and recruit additional agents; instead he moved to Lisbon and created bogus reports from a variety of public sources, including a tourist guide to England, train timetables, cinema newsreels, and magazine advertisements. Although the information would not have withstood close examination, Pujol soon established himself as a trustworthy agent. He began inventing fictional sub-agents who could be blamed for false information and mistakes.
The Allies finally accepted Pujol when the Germans spent considerable resources attempting to hunt down a fictional convoy. After the initial interviews carried out by Desmond Bristow of Section V MI6 Iberian Section, Juan Pujol was taken on. The family was moved to Britain and Pujol was given the code name "Garbo". Pujol and his handler Tomás (Tommy) Harris spent the rest of the war expanding the fictional network, communicating at first by letter, to the German handlers and later by radio. Eventually the Germans were funding a network of twenty-seven fictional agents.
Only guy to get high decorations from both sides; in The Deceivers you'll find out how the British realized something was awry from mistakes made in the info he was sending the Germans, and as noted above, brought in from the cold. He later played an important role in fooling Hitler about D-Daym wrote him a magnificent letter about how important it was to not get the response to the invasion wrong.
I remember well searching for the book The Wizard War: British Scientific Intelligence, 1939-1945 (http://www.amazon.com/Wizard-War-Scientific-Intelligence-193...) in the summer of 1978, the year it came out (the library hadn't yet gotten its copy).
I'm almost finished reading a UK printing of The Deceivers: Allied Military Deception in the Second World War (http://www.amazon.com/Deceivers-Allied-Military-Deception-Se...) which was first published in 2005 and it comments that a lot of its material was only recently declassified. Prior to it the only detailed history was the bit known as The Man Who Never Was: World War II's Boldest Counter-Intelligence Operation (http://www.amazon.com/Man-Who-Never-Was-Counter-Intelligence...) from the '50s, which wildly overstates the importance this particular bit of deception used for the invasion of Sicily. It was one of many pieces which in total achieved complete success, but it and they don't hold a candle in "boldness" to FORTITUDE SOUTH and QUICKSILVER (http://en.wikipedia.org/wiki/Operation_Fortitude) which convinced Hitler and most of the Wehrmacht high command for well over a month that the Normandy landing was only a feint.
Used copies of the book became a bit hard to find after The Wall Street Journal recommended it, but it looks like it will get a reprinting in October.
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