abstract:The dukes of Medina Sidonia are grandees of Spain, holding the oldest dukedom extant in the kingdom, first awarded by King John II of Castile in 1445. They were once the most prominent magnate family of the Andalusian region, the most well-known of which, Don Alonso de Guzmán El Bueno, 7th Duke of Medina Sidonia, commanded the Spanish Armada at the end of the 16th century.