Shortly after the end of the First Fernandine War, Ferdinand I of Portugal signed a treaty with John of Gaunt on 10 July 1372 in which they promised mutual aid against the Crown of Castile.

After signing the treaty, the Portuguese monarch ordered the seizure of Castilian ships in their ports, so that the supporters of Peter I were able to invade Galicia.

While the land assault was successful, Ambrosio Boccanegra sailed with a fleet of 12 galleys from Seville to Lisbon.

[3][4][5][6] Admiral Pessanha lost his post due to his performance in the battle and was replaced by Juan Alfonso Tello,[7] while Ferdinand I of Portugal was forced to ask for peace from Henry II, since no English reinforcements had arrived due to the aftermath of the catastrophe at La Rochelle and he could no longer hope for one with the Castilian fleet in front of the port.

This marked the end of the Second Ferdinand War and also the last service of Ambrosio Boccanegra to King Henry II.