After Philip 's death in 1506 , with Joanna supposedly mentally unstable , and her and Philip 's son , the future Emperor Charles V , was only six years old , Ferdinand resumed the regency , ruling through Francisco Jiménez de Cisneros , the Chancellor of the Kingdom .
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 .