The following year, 1380, when the King of Castile was in Seville, he ordered twenty galleys to be armed and sent to the aid of the King of France. Their captain was Fernán Sánchez de Tovar, and the King of France armed ten of these galleys at his own expense, in accordance with the treaties that existed between the two kings. Then, in the month of May, the King of Castile left the city.

At the time when he was in the town of Cáceres, in the diocese of Coria, having travelled through his kingdom, there arrived João Afonso Telo the Count of Ourém, and Gonçalo Vasques de Azevedo, the Lord of Lourinhã. They were ambassadors from the King of Portugal and had gone to negotiate the marriage between Princess Beatriz, the daughter of King Fernando, and Prince Enrique, the King of Castile's first-born son. The ambassadors explained that as a service to God and for the sake of peace and harmony, the betrothal of the princess to Fadrique, the Duke of Benavente, should be set aside. Don Fadrique was the King of Castile's brother, to whom she was given in marriage, as you have previously heard. The princess should instead marry this son, since she was still under age, and that was easily possible.

The King of Castile approved of this, and they made their agreements concerning the betrothal and other matters, upon which the King of Castile immediately sent three ambassadors to the King of Portugal. These were Juan García Manrique, Bishop of Sigüenza, the king's chief chancellor; Pero González Mendoza, his lord chamberlain, and Íñigo Ortiz de Estúñiga, head of the guard. They reached the town of Portalegre, where King Fernando was at the time, and they made and signed a treaty with him whereby when Prince Enrique reached the age of seven years the king his father would make arrangements for the prince to marry the princess, the King of Portugal’s daughter, by proxy; and when he reached the age of fourteen, the prince was to celebrate the wedding in public. The King of Castile would, in the month of September, convene the Cortes in his kingdom to have them approve that, after his death, his son and the princess were to be received as king and queen, and the Pope's dispensation was to be obtained so that they could marry.