I give up. Military history is just not my bag. I've read two thirds of the book and I just can't keep going. If I weren't listening rather than reading, I would have long since flipped to the last couple of chapters to read the author's conclusions and summary. Besides which, I have picked a really bad time to read a book about war and invasion in Europe when Putin has just sent troops into the sovereign nation of Ukraine.
However, I would recommend the book. It is well written and easy to follow--and on that basis, I'm giving it four stars.