 Supporters of King Ferdinand placed Medellín and Mérida under siege.The nuncio Jacobo Rondón de Seseña arrived at Castile with notice that Pope Sixtus IV had reversed himself and had annulled the dispensation previously awarded to Afonso V for his marriage to his niece Joanna.This gravely debilitated the legitimacy of the Joannist side and the pretension of the King of Portugal to the throne of Castile.