Since King Enrique was striving to capture those townships and villages which had not declared for him and because he realized that, whatever attempts he made, whatever deals he offered to their governors, none availed him anything in his efforts to win them over, he therefore laid siege to them and attacked them, resorting to every ruse and applying all the force needed for such an objective. Those in charge of such fortresses strove just as hard to defend themselves against him, as though the king and his forces were infidel Moors bent on conquering them and subjecting them to their power.

It was not just the king with his forces who was active, but also the queen his wife, for she had ample courage for the undertaking and likewise strove to lay siege to some of these townships. Among them she laid siege to Zamora, which was defended by Alfonso López de Tejada, along with his brothers, other noblemen and many troops, and who had declared for King Fernando. For several days, the town was under such pressure that Alfonso López entered negotiations with the queen, according to which, if help did not reach the town within a period of days, he would surrender it without further conflict. The queen accepted the arrangement, on condition that Alfonso López should hand over to her, as hostages, in order to guarantee the deal, his two sons, who were there with him and who, indeed, the father handed over to her of his own accord.

The deadline which they had agreed came and went, and no help reached the town, not even from Master Gregorio Campomorto, who forced his way into the town with sixty men-at-arms, despite its being under siege, but this was of no avail in respect of the town's defence. Alfonso López was urged to surrender the town, as the deadline had passed, but he temporized and vehemently declared that he had little inclination to do so.

The queen was so furious at this that she declared on oath that if Alfonso López did not surrender the town to her as he had agreed, then she would have his sons beheaded before his very eyes, should he deign to behold their fate. She then ordered this message to be delivered to him.