Nuno Álvares left Tomar where he had been staying and went to Punhete, on his way to the Alentejo, the region that he was in charge of. There he found out that a number of Castilians were in Crato preparing to leave for Santarém, and that there were others who wanted to leave Santarém for Castile. These people were travelling with a great number of mules loaded with things such as bedding, clothing, agricultural tools, and other items that might prove useful, which had been plundered by certain Castilians in the Santarém area and other places. It was decided that he should wait for two or three days for one group or the other on the road along which they were to pass, so that, with God's help, he would be able to fight against whichever group should happen to come along.

With this plan he left Punhete, and came to the road along which the Castilians would have to go in order to reach Santarém, or from Santarém on their way to Castile, and stopped at a little stream called Alperraiam and had a meal close to it, under some young ash trees. Before he sat down to eat, he stationed his lookouts at a distance of a crossbow shot and further away, on various hilltops, so that no one would be able to pass without his knowing it. It was his habit never to stop on the way unless he had lookouts during the day, and guards and scouts at night, posted both at a distance and close by.

The lookouts were in their position and he and all his men were eating, when suddenly one of his scouts approached swiftly and very quietly, saying that he had seen clouds of dust on the road to Santarém, and that he thought there were people approaching, some on horseback and some on foot. Nuno Álvares was very pleased at this news and immediately gave orders for the meal to be cleared away and the mounts saddled quickly and quietly. He told all his men to join him at once and do so quietly, which they did, as there was no reason for any delay, since they were armed at least with their helmets, and their mounts were saddled and ready for that which they were waiting for.