(Spanish: “one who goes before”), representative of the kings of Castile (Spain) who in the early European Middle Ages headed military expeditions and, from the reign of Ferdinand III (1217–52) until the 16th century, held judicial and administrative powers over specific districts. Greater adelantados (adelantados mayores) served as appeal judges and in times of war were responsible for organizing their territories' armies. Lesser adelantados (adelantados menores) held similar powers, but they were often stationed along the frontiers, becoming known as frontier adelantados (adelantados fronterizos), and figured prominently in the military conquest of the Americas. In the 16th century the office was replaced by that of alcalde (magistrate).