I read David Kahn's "The Codebreakers" (all 2000+ pages) years ago, and recently found James Rusbridger's "Betrayal at Pearl Harbour", which contradicts some of Kahn's book with later info, and claims (with a lot of documented evidence) that UK knew of Japanese intentions, but that Churchill kept it quiet from the US because he wanted them in the war. He also claims that the US had all the same info and capability, but failed to put it together because, unlike the highly integrated British system, they were split by army/navy and inter-agency rivalry and hostility; and that evidence of their culpability has been systematically expunged from the records (but not successfully enough).
Cryptanalysis, because of its strong ties with world politics and history, makes fascinating reading.
Any of you with an interest might like to know that Kahn also contains the full uncracked cypher for a legendary unfound hoard of treasure somewhere near Roanoak Virginia. Do you want to be seriously rich ?