Feudalism was complicated by a practice called subinfeudation. As already noted, a lord who had large landholdings would create vassals by parceling off fiefs in return for military service. But it was also considered lawful for the vassal who received a fief to pass on a part of that fief, in turn, to a lesser knight, also in return for military service. The practice of subinfeudation (subdividing a fief) often gave rise to divided loyalties. Since a knight could accept land from different lords, that knight would become the vassal of both lords. If the lords from whom he received both parcels were ever at war with each other, the vassal would have to declare one of them his "liege" lord and fight only on his liege lord's behalf.

The king remained an important part of feudal society. Although his kingdom was now fragmented and governed by an...