Juana was imprisoned for nearly 50 years, her right to regal power usurped in manoeuvrings by her mother Isabella I, father Ferdinand II, husband Philip I ‘the Handsome’ and son Charles I (Charles V, Holy Roman Emperor).

Her parents established the Spanish Inquisition, which coloured her childhood: at her mother's behest she was tortured for religious rebellion. She married Philip in 1496. He was unfaithful, cruel, intimidated and impoverished her, squandering her funds; her response was marked by jealousy, rage and violent behaviours: throwing herself against the wall in despair; and hacking off a rival's hair and stabbing her in the face.

Queen of Castile from 1504, around February 1505 the Cortes (parliament) was informed of Juana's unspecified ‘infirmity’, presumably by Ferdinand, and legitimised his right to administer Castile. In June 1506, father and husband cited ‘infirmities and sufferings, which for the sake of her honour are not expressed’ in a treaty leaving the government of Castile to Philip. Later the same day Ferdinand revoked this agreement, which was prejudicial to his interests and (he said) obtained by force.

In August 1506, Philip died suddenly of typhoid – or poisoning by Ferdinand. Juana's reason gave way and she never recovered. She would not part with Philip's embalmed body, believing it still lived, watching with affection as if it were alive. The corpse travelled with her, even from dinner table to bedside. She allowed burial but had the remains exhumed. When the coffin was reopened, she embraced and kissed the body. She opened the coffin to gaze at and talk to her beloved. Ferdinand ‘retired’ her and from February 1509 confined her to the fortified palace at Tordesillas. The cadaver was placed at the nearby convent of Santa Clara. Queen until death, Spain evolved from the union of her crowns. She rests in the Royal Chapel of Granada.

Alternatively – history is a fickle informant – independent correspondence does not indicate madness at Philip's death, or any subsequent symptoms of serious mental illness. Ferdinand originated or countenanced the rumour that Juana did not believe in the death of her husband. On 14 January 1507 she gave birth to her daughter Catalina and there are no indications that she was restricted in childcare. She visited her sister – later Catherine of Aragon – in England around October 1507, when there is no mention of mental illness. Ferdinand dismissed her servants and appointed a custodian accountable to him alone, a practice sustained by her son Charles: Juana was isolated, deceived, deprived, tortured and endured appalling conditions. She never expressed interest in visiting the tomb at Santa Clara. During the rebellion of August 1520 her keepers claimed that she had been oppressed, detained by force and imprisoned for 14 years as though she had not been sane; and she was evidently capable of speaking freely, with prudence and judgement.

Modern parallels? The extent of Juana's insanity is still disputed; sources are incomplete and contradictory; reasonable interpretations can be placed on behaviour in context; and, in family matters cui bono?