scutage

Scutage is a medieval English tax levied on holders of a knight's fee under the feudal land tenure of knight-service. Under feudalism the king, through his vassals, provided land to knights for their support. The knights owed the king military service in return. The knights were allowed to "buy out" of the military service by paying scutage. As time passed the king began to impose a scutage on holders knight's fees, even in time of peace.