Final answer:
Feudalism was a hierarchical system prominent in the ninth century featuring lords and vassals in a mutual relationship of land for military service. The Church was a major landholder and participant, with the system eventually weakened by societal changes and major events.
Step-by-step explanation:
The ninth century marked the rise of feudal societies, which were characterized by a rigid hierarchical system based on land ownership and the provision of protection. The foundation of feudalism was the relationship between lords, who were part of the nobility, and their vassals, to whom they granted parcels of lands known as fiefs. In exchange for the land and its resources, vassals pledged to provide military service and other forms of support to their lords, thereby ensuring a mutual relationship of protection and loyalty within this social system.
Medieval Europe's feudal system was built upon pledges of loyalty, or fealty, with vassals receiving the right to extract wealth from their land, on which peasants lived, in order to support their martial lifestyle, including acquiring horses, armor, and weapons. The Church, as a powerful landowner, also played a role in this system, where bishops could be lords of their own churches, maintaining a close relationship with the kingdom's monarchy.
Over time, European political entities evolved and the structure of feudalism began to weaken. Major events such as the Great Famine, Black Death, and Hundred Years' War had significant impacts that led to the transformation of this system. Cities saw a rise in the merchant class, while in the countryside, the feudal relationships defining the lives of serfs started to disintegrate, marking the decline of feudalism.