What obligation did vassals have to their lords in the feudal system?

In the feudal system, vassals had a specific obligation to provide military service to their lords. This relationship was central to the feudal hierarchy, where loyalty and service were exchanged for protection and land. Lords granted vassals fiefs—land parcels in return for their commitment to serve in military campaigns when called upon. Thus, the military service was not merely an obligation but also a crucial aspect of the power dynamics and security of the feudal state.

Other obligations were certainly part of the feudal relationship, such as loyalty and administrative duties, but the essence of a vassal's responsibility was directly linked to military support, which was vital in an era when territories were often contested and warfare was common. This commitment ensured that lords had a standing military force to defend their lands and interests.