The heredity of fiefs and the general establishment of sub-fiefs extinguished political government and formed feudal government. Instead of that innumerable multitude of vassals the kings had had, they now had but a few, to whom the others were subsidiary. The kings had almost no direct authority remaining ; a power that had to pass through so many other powers, and through such great powers, ended or faded away before it reached its goal. Such great vassals no longer obeyed ; they even made use of their sub-vassals in order not to obey. The kings, deprived of their domains, reduced to the cities of Reims and Laon, remained at their mercy ; the tree stretched its branches too far, and the head withered. The kingdom found itself without a domain, as the empire is today. The crown was given to one of the most powerful vassals.
The Normans ravaged the kingdom ; they came on a kind of rafts or small ships, entered through the mouth of the rivers, went up them, and devastated the country on both sides. The cities of Orleans and Paris halted these brigands, and they could not advance on either the Seine or the Loire.  Hugh Capet, who possessed these two cities, held in his hands the two keys of the unhappy remains of the kingdom ; a crown which he was the only one in a position to defend was conferred on him. It was thus that the empire has since been given to the house that holds firm the borders of the Turks.
The empire had left the house of Charlemagne at the time when the heredity of fiefs was being established only by way of deference. It even appears that it was established later among the Germans than among the French, for which reason the empire, considered as a fief, was elective. When, on the contrary, the crown of France went outside the house of Charlemagne, the fiefs were really hereditary in the kingdom ; the crown, as a great fief, was as well.
Besides, we are quite wrong to attribute to the moment of this revolution all the changes that had occurred or which occurred since. It all came down to two events : the reigning family changed, and the crown was joined to a great fief.