Dukedom of Frías

Duke of Frías is a hereditary title created in 1492 by King Ferdinand II of Aragon. It became one of the most important titles in Spain.

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 founder of this lineage was Juan de Velasco (1368–1418), Lord High Chamberlain-Chancellor Camarero mayor to the kings of Castile. His elder son, Pedro Fernández de Velasco, became the first count of Haro.

When the first count died in the 1470s, he was succeeded by his eldest son Pedro Fernández de Velasco, 2nd Count of Haro. Pedro Fernández de Velasco became the hereditary constable of Castile, a title which previously had been only a life appointment. His son, Don Bernardino de Velasco, third Count of Haro and second hereditary constable of Castile, received the title of duke of Frías.

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