When King Enrique reached Guimarães, he found that the town was more suited to defence and better armed than Braga, for it had been entered by Gonçalo Pais de Meira, a noble and resourceful knight, along with his sons Fernão Gonçalves and Estêvão Gonçalves, who later became Master of Santiago, and forty horsemen, as well as other noblemen from that region, with the result that within the walls were a goodly number of valiant men.

The king pitched his camp outside the walls on the first day of September and surrounded the entire township with the vast number of troops which he had brought with him. Those inside, both horsemen and foot soldiers, went out and skirmished with them. This was right at the beginning while the encampment was some distance away. The king ordered that the camp should be brought closer and that siege engines should be made ready. He then began to attack the town, whilst those inside strove to defend it, with the result that the assailants achieved nothing in their attack. It is said that King Enrique swore that he would not leave the place unless he captured it and gave orders for it to be attacked with such frequency as to giv e little respite to those inside the town. Though the town was subjected for three weeks to many, many stones being hurled at it from siege engines, it pleased God that not a single one ever injured any man, woman or animal. Those inside the town equipped other engines, hurling stones at those outside, injuring them, killing some of them and causing great confusion in the encampment.

One evening, Diogo Gonçalves de Castro, the father of Lopo Dias de Azevedo, made his way into the town, dressed in humble clothing and declaring that he was a member of the judiciary and was there to perform a marriage. However, the townsfolk recognized him, and he was at once arrested. Realizing that he faced death, he confessed that he and King Enrique had discussed a plan whereby he would set fire to the town in four places and that, while the inhabitants rushed to put out the fire, King Enrique would make every effort to enter the town. In view of such treachery, they put him to death and abandoned his corpse to the dogs.