The feudal system had to confront various difficulties or crises, such as conflicts among vassals, competition with rival lords, invasions by foreign powers, epidemics, and rebellions by peasants or serfs. It responded to these challenges through strategies such as fortification of castles, alliances with neighbors, religious reforms, and diplomatic negotiations. However, these measures were not always effective, and the feudal system eventually gave way to new forms of social organization and governance.