Any reasonable man can understand how much cause the king had to be so upset at such an incident. However, if we put such causes to one side, as befits great lords, these are his deeds, in a short and brief account. He crossed the Minho and took Salvatierra. He arrived at Sotomayor and from there set up camp threatening Tuy; he besieged it in such a manner that no one could easily enter from the outside, nor could the besieged population easily make their way outside. However, the town was well prepared with men-at-arms, foot soldiers and crossbowmen, and worthy knights willing to defend it, men like Pay Sorredea, who had principal responsibility for the town, Pero Fernández de Andrade, his father-in-law, who had come to his aid, Pedro Díaz de Córdoba, and Gonzalo Azores. With them were up to 300 lances, not counting foot soldiers and crossbowmen, and they had bread, wine and many other provisions, as well as the courage and will not to surrender lightly.

The king encircled the city with his trebuchets, which shot at it from all sides. Because of the great damage they were causing, an agreement was reached: that the trebuchets should not fire at night, nor should those inside shoot any poisoned arrows. The king consented to this, because he was not at all keen that the town's ancient and noble cathedral, which is reputed to contain the body of Friar Pedro González, should suffer damage from his side.

Furthermore, those on the inside came out frequently to skirmish and, with good, strong crossbowmen they inflicted great harm on the troops, for however good the latter's arms, they did not prevent many being wounded, a number of them dying. So much was this the case that the Portuguese greatly feared them. Likewise, the trebuchets inflicted great damage on the city, killing a number of people.

At this point, the order was given on a particular day to set up the siege ladder and make an assault on the town. In this action many notable squires chosen by the king duly participated, not for their noble lineage but because they were known to be worthy men-at-arms.