Among the best chapters is editor Ralph Erskine's "Enigma's Security: What Germans Really Knew." This hair-raising essay is implicitly a powerful argument for alternative analysis, interagency intelligence sharing, and the breaking down of compartmentation. Erskine reports, for example, that in March 1943 the German Kriegsmarine's SIGINT service decrypted an Allied "U-Boat Estimate" that noted the location of a group of U-boats, allegedly on the basis of direction finding. The Kriegsmarine knew, however, that those U-boats could not possibly have been located by means of direction finding because they had not emitted signals. Five months later, the Abwehr passed along a report from a source in Switzerland that "a special office [in England] has dealt exclusively with solving German codes. It has succeeded for some months in reading all orders sent by the Kriegsmarine to U-boat commanders." More astounding still, in March 1944 a German technical commission firmly established that before the war the Polish Cipher Center had broken Enigma, the German code system. However, the commission's report never got to the Kriegsmarine's Marine Communications Service, which was doing a review of naval Enigma's security. It probably would not have mattered, however--the service was chartered "to explain for what reason reading of our signals . . . could not have taken place." John Cripps, a graduate student working on a doctoral dissertation on "British Signals Intelligence and the War in Yugoslavia, 1941-1944," provided a chapter that adds to the open literature on another case in which intelligence demonstrably contributed to policymaking. He describes how Bletchley's work was central to Churchill's ideologically surprising decision to support Tito and his Partisans instead of Mihailovic's Chetniks. Bletchley was, to varying degrees, reading the communications of everyone involved: the Germans, Italians, Partisans, and Chetniks, even the Slovene Communist Party and the COMINTERN that provided guidance to Tito. Cripps demonstrates how this mass of SIGINT proved to Churchill that Tito was harassing the Axis occupiers to greater effect than Mihailovic.

[...]

"Colossus and the Dawning of the Computer Age," by computer historian Prof. Jack Copeland, has a different flavor than the rest of the book, but is a valuable addition. Copeland notes that history books still sometimes erroneously state that the first electronic digital computer was the American ENIAC, completed in 1945. Bletchley's "Colossus" was completed in December 1943 and put to work on the German teleprinter cipher, which the British called "Tunny." ENIAC got the credit, however, because it was not a secret whereas Colossus was. It was not until 1975 that a picture of Colossus was declassified, and it was 1983 before a description of how it functioned became available, and 1996 before the United States--not the UK--declassified a description of the use to which it had been put. No wonder ENIAC made all the textbooks.

Lastly, this lengthy monograph on the history of Operation Ryan, Operation ABLE ARCHER 83, and the Soviet Union's later reaction to these actions taken during the Reagan and Thatcher years, and the ensuing war scare of 1983, is absolutely dead fascinating, not to mention extremely little known. (Via Charlie Stross)

Read The Rest Scale: 5 out of 5.