I've observed a principle that militaries build to win the last total war they fought. This is why guys like Billy Mitchell ( http://en.wikipedia.org/wiki/Billy_Mitchell ) were ignored about the importance of air power leading up to WWII. The status quo was to gear up for another WWI, complete with entrenched and barely mobile front lines. But of course the German Blitzkreig, a brilliant archetype of maneuver warfare…
But it was the Siegfried Line[1] in WWII that let the Germans concentrate their whole army against the Poles and defeat them before turning west, and that let them attack where the French weren't rather than have to defend the current border. So German tactics in WWII were dependant on the same static defenses that the French used, but they took that and added a maneuver component instead of replacing it entirely. Ma…
What makes this particularly galling is relative strengths of the two armies at the time; the Allied forces in northeastern France had significantly more tanks (for example) available there than the Germany army had in total, let alone defending the western front. It's far from impossible that a serious, concerted attack on western Germany in the 1939-1940 'phoney war' period could have had enough success to significantly alter the course of the war and turn it significantly into a land war in western Germany for much of the period.