fleets of twenty galleys and, on special occasions, of up to thirty. The Castilian kings used them in the struggles for control of the Strait of Gibraltar against the Muslims and also in raids against England during the Hundred Years' War. For its construction and armament, a labor force of between 400 and 500 artisans was temporarily mobilized, who, in exchange for working for the Crown for half the usual salary, enjoyed great fiscal privileges throughout the year. For this reason they were called "francs". In addition, the Crown possessed in the Shipyards an indeterminate number of slaves, mainly Muslim prisoners, who were in charge of the most painful tasks. The wood for the construction of the ships was brought from forests owned by the Crown located in the Sierra Norte de Sevilla. The naves could hold a large number of galleys and vessels, as well as all the equipment for assembly, repair and maintenance. The spoils of war were also kept there. Caulkers, carpenters, blacksmiths and other artisans worked inside it. Those who work there were under the authority of the alcaide of the Alcázar of Seville (the palace-fortress nearby) and the Shipyards. This warden was appointed by the king. The position of warden used to fall to a nobleman who, at times, delegated the exercise of his work to a man of trust. In the first third of the 15th century the Shipyards set up its last large fleets of galleys. Fifteen ships were destined to an incursion against England in 1420 and an indeterminate number to the war against Aragon in 1430. After these contests, the orders of the Castilian kings became increasingly scarce. In the middle of the century the hulls of some twenty galleys, built but not armed, were rotting in their facilities. During the last stages of the Reconquista the Catholic Monarchs installed the seat of their court in Seville. At the end of the 15th century, some of the repair works of the shipyards were carried out by order of the latter. Later, in 1493, the Catholic Monarchs approved that the fish market move from the Plaza de San Francisco square to the first nave (the one closest to the Postigo del Aceite gate) of the Shipyards. In that nave several fish markets and some houses were placed. On February 14, 1503, on the occasion of the constitution of the Casa de Contratación