Joanna of Castile (b. 1479)
Joanna (6 November 1479 – 12 April 1555), historically known as Joanna the Mad (Spanish: Juana la Loca), was the nominal queen of Castile from 1504 and queen of Aragon from 1516 to her death in 1555. She was married by arrangement to Philip the Handsome, Archduke of Austria of the House of Habsburg, on 20 October 1496. Following the deaths of her brother, John, Prince of Asturias, in 1497, her elder sister Isabella in 1498, and her nephew Miguel in 1500, Joanna became the heir presumptive to the crowns of Castile and Aragon. When her mother, Queen Isabella I of Castile, died in 1504, Joanna became Queen of Castile. Her father, King Ferdinand II of Aragon, proclaimed himself Governor and Administrator of Castile.: xxxiii  In 1506 Archduke Philip became King of Castile jure uxoris as Philip I, initiating the rule of the Habsburgs in the Spanish kingdoms, and died that same year. Despite being the ruling Queen of Castile, Joanna had little effect on national policy during her reign as she was declared insane and confined in the Royal Convent of Santa Clara in Tordesillas under the orders of her father, who ruled as regent until his death in 1516, when she inherited his kingdom as well. From 1516, when her son Charles I ruled as king, she was nominally co-monarch but remained confined until her death. Joanna's death resulted in the union of Spain and Germany, as the Holy Roman Emperor, Charles V, was also King of Castile and Aragon, since 1516.