While the fleet of naos and barges on which the English came were all lying at anchor off the city, news reached King Fernando that the fleet of Castilian galleys were coming to cause harm and damage to the city and particularly to the English naos. The king agreed that it would be better if the English fleet and all the other ships lying there went to Sacavém, which is 2 leagues from the city, and all came to anchor there to be safe. The largest naos lay at the front, their aftcastles to seaward, armed and fitted with a pavisade, and equipped with cannons and other devices with which to defend themselves. In addition, two thick chains were hung in front of them, stretching from one side to the other, so that no enemy ship could do them any damage. On land, there were cannons and trebuchets to help in their defence, with a great number of men, should there be need for that.

The fleet was lying in this fashion when Fernán Sánchez de Tovar, the Admiral of Castile, came with the fleet of galleys with which he had routed those of Portugal at the battle of Saltes, hoping to find the barges and naos of the English before Lisbon, ready to cause them as much damage as he could.

When, however, the Castilians arrived in front of the city, they found the river clear of ships and discovered that they were all at Sacavém. When they went there and saw that the river and the naos were protected in that manner, they turned about and, finding no way in which to cause damage, as had been their intent, they sailed back to Seville. The English naos, having received trustworthy information that the Castilian galleys would not return for a while, and that they could do them no harm, made ready and left the city, both the naos and other ships, some of them loaded with merchandise, setting off on their voyages on 13 December 1381.