Duke of Frías  Duke of Frías () is a hereditary title created in 1492 by King Ferdinand II of Aragon and conferred to his son-in-law Don Bernardino Fernández de Velasco, 2nd Count of Haro, Constable of Castille, and Viceroy of Granada. It is one of the most important titles in Spain and one of the first titles to receive the honor of Grandee of Spain by Emperor Charles V in 1520. The House of Velasco was one of the most powerful and influential noble Castilian families of the Middle Ages and the beginning of the Modern Era. Its original territories were situated around Burgos, Álava and eastern Cantabria. The lineage was of distant royal origin, being the Velascos a minor branch of the Astur-Leonese dynasty, but re-elevated when Don Juan de Velasco (1368–1418), was appointed hereditary Lord High Chamberlain-Chancellor or "Camarero mayor" to the Kings of Castile. His elder son, Pedro Fernández de Velasco, became the first Count of Haro. When the 1st Count died in the 1470s, he was succeeded by his eldest son Pedro Fernández de Velasco, 2nd Count of Haro who became the hereditary Constable of Castile, the highest ranking military office in Spain not considering the King. His son, Don Bernardino de Velasco, 3rd Count of Haro and second hereditary Constable of Castile, received the title of Duke of Frías. After becoming a widow, he then married Doña Juana de Aragón, illegitimate daughter of King Ferdinand II of Aragon. In 1520, Emperor Charles V made the 2nd Duke of Frías one of the first Grandees of Spain, thus making the Dukedom of Frías one of the 25 most important titles in the Kingdom of Spain, known as of ""Grandeza Inmemorial"" or ""Inmemorial Grandeeship"".