Tonk. Ow. Tonk. Ow. Tonk. Ow.
Medieval Moment: If you were a king in the Middle Ages, there was at least some expectation that the knights serving under you would perform duties as part of their tenure for the land they occupied. This could range from fighting in tournaments, going to war, providing defence, or training on foreign military campaigns. In some cases you might even be expected to pay a scutage in lieu of service.