With the peace agreed, and the Portuguese wanting to draw up the treaty, they were confronted with a formidable doubt which worried them a good deal, namely the tender age of the King of Castile, who was a minor aged seven. At that age he could not swear an oath or be bound by the conditions of such a peace until he was fourteen years old. Alternatively, he could have authority bestowed by the magistrates of his court, but the necessary procedure was so complicated and took so long that it would be very difficult for him to get it, and not soon enough.

‘Therefore, my lords’, said the Portuguese to those who were charged with this task, who were the Bishop of Zamora and Pedro Yáñez, a doctor of laws, ‘what are we going to do about this problem? For when the king reaches fourteen years of age, he could well accept or reject this treaty. Supposing he accepted it, such a peace in the meantime will seem more like ravages of war or truces rather than a rightful and perpetual peace, until that age at which the law holds a man to be perfect in his understanding of whether what he does is right or wrong, which is accounted to be twenty-five years. Below this age, whatever he does is in vain and may be deemed fallacious, and will not be valid. Thus, the firmness of this peace would depend purely on the oaths of the queen, the prince, the prelates, the nobles and the representatives of the towns.

‘Without validating the peace treaty in this manner, there would be no reason why the letter of this document should be fulfilled until the day when the king, at the age demanded by law, confirmed it by oath. In any other way, the King of Portugal would remain without a peace and suffer grave loss, having given aid to his enemies which they could use to destroy him and make war against him. Added to this, there was the huge cost of fitting out fleets, and many forms of support that would certainly need to be provided, when they were required of him.’