 Joanna was allegedly mentally unstable, and Joanna's and Philip's son, Charles, the future Emperor Charles V, was only six years old.Cardinal Francisco Jiménez de Cisneros, the Chancellor of the Kingdom, was made regent, but the upper nobility reasserted itself.Ferdinand led an army against Pedro Fernández de Córdoba y Pacheco, the marquis of Priego of Córdoba, who had seized control there by force.