[1][2][3] The treaty granted Isabella the title of Princess of Asturias and so she became heiress presumptive to the Crown of Castile.
A civil war began in Castile in 1464 when a group of noblemen rebelled in an attempt to force the abdication of Henry IV.
Rather than continuing the civil war, Isabella preferred to negotiate with Henry IV sending Antonio de Veneris [es] as mediator.
With the treaty, the allegiance of the whole Kingdom of Castile was to return to the King and Isabella was to become his heiress presumptive, receive the title of Princess of Asturias as well as a large endowment.
Finally, Joanna, the King's daughter, was removed from the line of succession to the throne through the annulment of Henry's marriage to his wife.