A little side note concerning Germany here, if people don't mind. A lot of people seem to take Germany's ultra-fast drive to the coast for granted, when, in fact, Von Manstein was repeatedly told to shut up by the OKW. When he wouldn't, they banished him to command a division standing guard in East Prussia. It was sheer luck of the draw, that Guderian got on board and managed to "leak" the plan to Hitler in person.
Another example of history being a hair away from being radically different.
And France's Dyle-plan was set to counter the first battleplans the OKW drew up. It could have worked.
Very good point and why I often ascribe the German success in 1940 as having more than a small dose of luck involved. So many things had to go a certain way (and nearly didn't) for things to work out the way they did.
The purge most likely would have had an impact on the behaviour of those not purged - less dissent, less people talking up if they thought something wasn't being done well. This cultural impact on those remaining could be even larger than the impact of the loss of officers, in terms of military effectiveness.
I agree with this point. I think the purge discouraged initiative because it left those remaining with the idea that if they stuck their head up it might get chopped off. There has, of course, been plenty of discussion on whether initiative in one's battlefield commanders is a good or bad thing.