The term Liga Nobiliaria (in Castilian: Liga Nobiliaria or Gran Liga Nobiliaria, in English: Noble League) is generally used to designate political movements of nobles of the Kingdom of Castile that arose in the 14th and 15th centuries. They are equivalent to today's parties, and were motivated mainly by attempts of monarchs to diminish the opposition's powers and privileges. In a broad sense, the term "Noble League" or "League of Nobility" appears associated with the more or less volatile associations formed by the Castilian nobles of the Middle Ages to oppose the tendencies toward centralization and concentration of power on the part of the kings and the forces closest to them. It is common for the term to apply specifically to the group of nobles formed in the mid-15th century who participated in the Farce of Ávila, in this city on June 5, 1465. It consisted in a staged deposition of Henry IV and the proclamation of his brother Alfonso as king. Overview The league was officially founded on May 16, 1464, to defend the rights of the infante Alfonso to the throne and to prevent the infanta Isabella from marrying without the league's consent. They had previously formed a "league for the 'Good of the Kingdom' and 'recognition of Prince Alfonso'" in 1460, which John II of Aragon and Navarre joined on April 1, 1460. The group played a pivotal role in the political-military conflicts that marked the second half of the 15th century in Castile and in the War of the Castilian Succession, during which the league supported Joanna la Beltraneja and her husband Afonso V of Portugal against the Catholic Monarchs. Although most of the nobles in the noble leagues supported Joanna's succession to the throne of Castile after the death of her father Henry, sometimes the term "noble league" is also used to refer to the nobles who supported Isabella, led by the Mendoza, whose head was then Pedro González de Mendoza. History The 14th and 15th centuries in Castile were marked by a power struggle between supporters of a stronger royal power and the large feudal lords. The Castilian Civil War (1366-1369) was won by Henry II with the support of the nobles, but the nobles lost some of their influence during the reign of Henry III, regaining it again in the reign of John II, especially when the then-called Gran Liga Nobiliaria managed to