"At the beginning of the eleventh century France was the only feudal state in Europe. (...) Actually France was not a single state but an alliance of feudal principalities bound together by the feeble suzerainty of the king. In real power the king was weaker than most of his great vassals. His demesne was small and he could not control the barons of the lle de France. The monarchy survived largely because of the support of the church, which was inclined to prefer one master to many, and the resources that could be drawn from church ﬁefs.
While some of the great lords such as the count of Flanders and the dukes of Normandy and Aquitaine had obtained control of the bishops within their lands, the prelates of Burgundy and Champagne depended on the king. The bishops had large, rich ﬁefs with many knightly vassals. Hence the man who appointed the bishops had the use of extensive resources. Nevertheless, the Capetian monarchy of the early eleventh century could do little more than survive. In the lle dc France it had little authority and outside none whatever."
This blog quotes form Baldwin, M. W. (ed.): The first hundred years (1969); source illustration medievalchronicles.com