With the treaties signed and the alliance made, the duke was getting ready to go to Spain with a powerful force. At this point, the Portuguese Captain General of the Fleet, Afonso Furtado by name, arrived one day with the ships and galleys which had left Lisbon while the king was laying siege to Chaves. He landed at a place known as Fowey, where he encountered Lourenço Fogaça, who had gone there to deal with a number of matters relating to his mission, and he returned with him to London in the galleys.

A great fleet of naos and other vessels was assembled at Southampton and Plymouth for the duke's voyage, and all his men made for these places in order to embark. The duke left those shores and set his course, intent on landing in Galicia, which lies in Castilian territory. Finding himself sailing into a headwind, he was forced to put in at a place called Brest, a very strong castle in the Duchy of Brittany, which Olivier de Clisson, the Constable of France, was at that time besieging with a mighty force. Close to the castle he had ordered the construction, a mere crossbow shot away, of a wooden fort, as sturdy as it was possible to build, in which his troops took shelter and kept all their supplies.

When the French saw the fleet arrive, they realised only too well that they were English, for rumours about them had been widely aired beforehand. Recognising also that the duke was approaching, most of the assailants began to flee, and many of them took refuge in the fort. The duke landed with his troops, and they began to attack it. Fearing for their lives, the defenders fought hard but, when they saw that there was no means of holding out, they pleaded with the duke to let them live in exchange for his seizure of the fort and all it contained. The duke was content to do this and had the fort destroyed. By this the English gained large quantities of provisions and other items that the enemy kept in the fort and thus they were safe for the time being.

From Brest the duke sailed in fair weather throughout the remainder of his journey and reached the town of La Coruña, where it was his intention to moor his fleet.