In retrospect, it seems perfectly obvious that everyone should have known what was coming, that this was, after all, the rise of the biggest evil mankind had ever seen.

But when you put yourself in the shoes of these diplomats, journalists, writers, casual visitors, as I did, it paints a very different picture. History is always perfect in hindsight. It’s not perfect at the time. So I wanted to know, what did they know, when did they know it, and what did they get wrong, and why did they get it wrong?