The war in Ukraine, so far anyway, has seen a smaller but better trained, equipped and motivated force of Ukrainians just give the much larger Russian army fits.
It reminds one that, in war, things don’t always go according to plan. To borrow from Mike Tyson, everybody has a plan until they get hit.
By World War II, the Germans in particular had mastered the elements of what the Allied countries called Blitzkrieg (Hitler himself said this was a silly word and it was apparently not used by the Germans) and the Wehrmacht refined armored tactics to an unprecedented degree.