after isabella's death, her kingdom went to her daughter joanna. ferdinand served as the latter's regent during her absence in the netherlands, ruled by her husband archduke philip. ferdinand attempted to retain the regency permanently, but was rebuffed by the castilian nobility and replaced with joanna's husband, who became philip i of castile. after philip's death in 1506, with joanna mentally unstable, and her and philip's son charles of ghent only six years old, ferdinand resumed the regency, ruling through francisco cardinal jimenez de cisneros, the chancellor of the kingdom.