This is both an interesting and disturbing book to read. The brilliance of the cryptographic minds that went into breaking the codes in the first place is gobsmacking. But, like so many other things, it was part inspiration and part perspiration. Without the constant slog of trying to make sense of intercepted messages, much of this information might have been lost.

The disturbing part comes from those in the UK and America with Anti Semitic views throughout the years leading up to WWII that dismissed or downplayed the information. There might have been options and decisions that could have paved the way for more immigration out of Nazi Germany or at the very least the condemnation of the world, for all the good that would do. The fact that the Nazis tried so hard to keep things secret shows an awareness of how perverted they were.

The second disturbing part was when the information was, finally, seen for what it was- a holocaust-, to tell the world would have tipped their hand at how much was being intercepted. Even someone like Churchill, who had advocated allowing more refugees into Britain, realized the overall course of the war, especially in areas of action, could be compromised and they kept silent while the exterminations were ongoing.

The only good part of that decision was after the war, there was lots of evidence to present to courts so that justice, too late for so many, could be done. Four purrs and two paws up.