Admittedly, my knowledge of the details of the Seven Years War or that of the Austrian Succession, or others of the earlier 18th Century is limited, but in spite of discussion of squadrons, don't a number of the cavalry charges in the battles of those periods count as massed cavalry charges?
I ask simply in reaction to the notion of either Napoleon OR Murat OR anyone else in the French Revolutionary or Napoleonic period being creditte with having invented the concept, if that was one sense in which you used the term "developed." Although I suppose it could certainly be argued that perhaps the concept was extended further during the period.
But there's ol' Fritz, among others, out there with quantities of cavalry that sometimes begin to approach the numbers of foot-sloggers available, leaving one with the inescapable impression that there must have been A LOT of horse-flesh in motion.
Just wondering -- Howie