I have no quibble with the fundamental concept that an army's commander is the ultimate source of battlefield authority, and a massed cavalry charge would require his authorization in some fashion.
My question is how the cavalry was made to act in such a great body, by what practical methods werethe many pieces directed by one mind in an age of no radios, limited mapping, little time to explain to many officers. My assumption is a heavy reliance on the use of regulating units and conformance by others to establish a vast web of direction, but it is a very indirect methodology, not capable of much finesse.
Digby's question seemed to be: who got credit for developing massed cavalry charges during the period, phrased in a way that implied (correctly?) that it was the French. Of course, it isn't clear what the threshold is that defines "massed": a couple thousand, 6-7,000, some other quantity of troopers or squadrons, or regiments, or brigades, or divisions? If it is true that Austria, Russia, or Prussia no longer used cavalry in "mass," a natural question might be: why not? Possible answers lie in altered military perceptions and doctrines based upon past experience, or upon current (in)capabilities to actually conduct massed cavalry action, for they certainly have the numbers for it.
To the extent that the other great powers were incapable of it, it would be interesting to know why that was, why the French were able to do it with similar tools and they weren't. It is all very well for Napoleon to nod, but at least several thousand troopers have to get the news and share a coordinated process and objective!
Cheers - Howie