The king left Lisbon and went to the Minho. Some days before, [three men] had come to Portugal to arrange a truce on behalf of the King of Castile: his confessor, Friar Fernando de Illescas of the Order of St Francis, Pedro Sánchez, a doctor of laws, and Antón Sánchez, a doctor in canon law. They arranged a suspension of hostilities for a few months while they reached agreement on other things.

At this juncture, at the end of that period, the king decided to lay siege to Tuy, a town in Galicia near the River Minho, which marks the boundary between the two kingdoms. He arrived there on 14 August of the aforementioned year of 1389. The reason for his move against it was, according to what some people relate, that Pay Sorredea, who was there defending it, had secretly sent to tell the king that he wanted to go over to him, and hand over the town, and that he should come to receive it. Believing this to be the case, the king decided to go there, thinking to gain it in this way. The Galician did it with the intention of enticing him in, according to what some people affirmed; furthermore, the King of Castile knew about it and everything was done with his consent. This is the opinion of the doctor we have named, in the treaty which he drew up and which ends with the chapter where it says: Hoc thamen fraudullenter faciebat.

Now when the king saw the deceit that had been perpetrated on him in this way, he began to besiege the town. He had siege engines set up to shoot upon it and had one placed in the river, on top of a quantity of stone that he ordered to be thrown in as a foundation. From all sides, they visited great destruction on the town, save the cathedral which they did not target. Those that could do so gathered together there, along with their belongings. He made a siege tower, a great siege ladder, and wooden protections for the assault. He sent to Oporto for the queen, for her to see how he was attacking the town; she came and was with the king at the siege.