Having rested, the king decided to send a message to Aires Gomes urging him to surrender the castle to him; he put to him all the reasons which could persuade him to do so, stating that he was well aware that he and all his lineage were noble Portuguese and that, for the honour and well-being of his native land, it was his duty to help to defend it, even if he did not possess any part of it; this was all the more so, given that Aires Gomes was entitled to an inheritance in it. He was also well aware that to strive to be against one's country and to help in its destruction seemed to him, the king, very strange; for that reason the king entreated him to abandon his plans and transfer his forces to the service of his country. Moreover, he promised to increase so greatly his honour, rank and wealth that he would consider himself well content; alternatively, he could name whatever he would like to be granted to him and he, the king, would be happy to authorise it.

However, neither these nor all the other excellent arguments that the king sent to him were successful in eliciting any other response than that he had no intention of accepting. Aires Gomes took this stance because he was determined to defend himself. Furthermore, if he were to find himself in difficulties, his plan was to negotiate, for, with the King of Castile hurrying to his aid, or ordering others to do so, he considered that this would bring him great honour and the opportunity for him to receive huge rewards. Consequently, he persisted in holding out, along with his wife and others who advised him.

At this point the king decided to launch an attack on the inner bailey. He summoned from Oporto siege engines, weaponry, troops, artisans and everything else necessary for such an attack. He ordered the construction of a siege tower on top of some nearby houses, so that crossbows could shoot from there. Wooden scaling ladders were made for placing against the ramparts. He also ordered the construction of a huge siege ladder, which was the first the king ever made. Great quantities of firewood were assembled in order to set fire to the gates.