Definitely it was the reliance on static defense that caused the western European nations to fall so quickly, at least as in my opinion the gravest error of all. However, keep in mind that it was also the strategy that won the Allies the first World War, so naturally it didn't seem that outdated in 1939 and 1940. As for early Blitz maps, I'd definitely like a map in Norway with British or French troops (or perhaps both ;)).
A tool I found usefull (& I think a few mappers may have as well) in looking at battlefields is google earth. Look for eben emaul with that & you can still see pretty much how it was laid out. Though there are better maps of the fortress layout to be had for sure. I have a pretty good special opperations book with maps of it somewhere. Textbook SpecOp.