Juana I, also called Juana La Loca , was born in 1479 in Toledo. She second daughter of the Catholic Monarchs; the only one who survived her parents. In 1496, she married Felipe el Hermoso , Archduke of Austria (son of Maximilian I, German Emperor, and his wife, Maria of Burgundy).
On February 24, 1500, Juana I had her son Carlos in the city of Ghent (Belgium); On March 10, 1503, her son Fernando was born in Alcalá de Henares (Madrid). Juana wanted to return to Flanders with her husband, who had already left there; but her parents confined her in Medina del Campo (Valladolid), under the pretext that her mental health was beginning to fail; but, finally, they agreed to let her go on March 1, 1504. After the death of her mother on November 26 of this same year, Juana was recognized as queen of Castile in the Cortes de Toro (Zamora) on January 11, 1505. Her father took charge of the regency of Castile. After her, the brief reign of her husband Felipe el Hermoso took place. She then she was made again in charge of the regency of Castile her father in 1507.
Later, King Henry VII of England asked Ferdinand the Catholic for the hand of his daughter, Juana; but the latter, who already knew that he was going to have a son by his second wife, locked up his daughter Juana in Tordesillas (Valladolid) in February 1509, and delayed the negotiations for Juana's wedding with the English king, until the April 21, 1509, pretender Henry VII died; and, on May 3 of that same year, the son of Germana de Foix, second wife of Fernando el Católico, was born; but, when the child died shortly after birth, all the projects of his father were frustrated:among them that the crown of Aragon did not get to unite with Castile; but, when his plans failed because he could not have another descendant for the crown of Aragon, as much as he tried, he left, by testament, to his daughter Juana, all his estates; Therefore, when Fernando el Católico died in 1516, Juana I came to concentrate under her power all the domains of her parents, belonging to the crowns of Castile and Aragon.
It is not clear that Juana I was crazy; it is enough to read a letter from her, dated May 3, 1505 in Brussels, addressed to Mr. De Veyre, to see that the only thing she had was certain attacks of jealousy, because of her husband, who was quite a libertine, since he had public affairs with a court lady. Apparently, Juana's madness was an invention of Fernando el Católico, according to Juana herself, since she wrote:"... there is no shortage of people who say that he pleases because of governing our kingdoms...". For this, her father locked her up and tried to prevent her from marrying the English king; because thus, according to the testament of Isabel I, Fernando el Católico could govern the kingdoms of the crown of Castile for eleven more years, until his grandson, Prince Carlos, was twenty years old. Juana I was locked up in Tordesillas forty-six years without leaving her palace; so even if she wasn't crazy at the beginning of her confinement, it wouldn't be surprising if she had been driven crazy to some extent by the end.
During the reign of her son Carlos I, her name was attached to his in public documents. Juana I died in 1555 . From her marriage to Felipe el Hermoso, she had two children:Carlos and Fernando; and four daughters:Isabel (married to the King of Denmark), María (queen of Hungary), Leonor and Catalina (queens of Portugal); Leonor married, in second marriage, with Francisco I of France.