Baron, BAR uhn, is the title held by noblemen in the lowest rank in the British peerage. This rank was introduced into England after the Norman Conquest (1066). The king bestowed the rank on those to whom he granted land in return for military service. The barons were later divided into greater and lesser barons, according to the amount of land they held. The lands of these first barons were handed down from father to son, thus establishing the hereditary aristocracy.