Basically the title. Given the circumstances, I believe she was the tragic victim of a power struggle but I'd also like an accurate historical basis for this.
Would also like a recommendation for a book about her life, English is preferred but Spanish is ok if it's a very accurate/interesting source unavailable in English.
Thanks!
This is a good question and I've attempted to answer this here. It is quite certain that she suffered from serious mental illness at the end of her life. It is widely accepted that she underwent mental abuse from her husband when she was first sent to Flanders, and it is very likely that this made the situation much worse.
We know for sure several things:
As a child, she was considered highly intelligent, well read, a great bridal candidate. However, her Portuguese grandmother was reported to have mental illness, so she may have genetic predisposition to mental illness.
When she was married to Philip the Handsome, she was sent to the Burgundian Low Countries and she didn't return until much later in life. As Philip's wife she was undermined personally and politically. Philip had many mistresses, and harbors ambition towards Castile and Aragon, that he pursued until his death. This is when she started to be confined, ostensibly due to mental illness.
When Philip and Juana went to Spain to press her claims as Princess of Asturias, following her elder brother's death, Ferdinand at first tried to keep himself as ruler of Castile even though Isabella left him only as regent. Ferdinand had few supporters in Castile however, partly due to close ties between Castile and the Low Countries at this time: they were close trading partners and both disagree with Ferdinand's policy toward France. After some political maneuvering, both Ferdinand and Philip agreed that Juana was not fit to rule due to her mental illness. On the same day, upon return to Aragon lands, he disavowed this agreement. So we may think of all that as highly politicized, but this does not answer whether Juana was in fact mad. However, Philip left for Flanders by himself, while a pregnant Juana stayed in Spain. Some say this is when her mental illness started to show obvious signs, including periods of melancholy, and even wandering about beyond the limits of the castle of Medina del Campo she was staying in, with worried servants scurrying about trying to talk her into coming back inside.
After Philip died, she tried to press claims to rule Castile herself. The country fell into chaos, and Cardinal Cisneros, against Juana's wish, swiftly set up a regency council and invited Ferdinand to act as regent of Castile again, this time on behalf of her son Charles who was then in the Low Countries and who would become Charles V (Carlos I of Castille).
During the Revolt of the Communeros, despite pleas from the rebelling faction, Juana refused to sign any agreements or declarations. By this point she was already fully confined. She refused to rule and yet she also refused to allow anybody else to rule.
So from that we know that reports of her madness started after she was married to Philip of Burgundy. That there was significant motivation to over play it, by all sides, sometimes at different times. And that towards the end of her life she was still seen as a viable political pawn.
Sources: