On the night of 11 December 1474, Henry IV of Castile lay in agony, likely suffering from a urinary tract blockage. In the early hours of the following morning he died, setting in train a constitutional coup with a 23-year-old woman at its helm.
Henry’s much younger half-sister, Isabella, was based at the Alcázar of Segovia. This impressive castle, home to royal archives and treasure, stood atop a rocky crag at the confluence of two rivers in the Guadarrama mountains of Castile. From there, she announced herself as queen of Castile.