Seeing that he was now too late, because of De Clisson's sortie, Charles of Blois recalled his army from the attack, in which he could only have suffered heavily from the arrows of the archers and the missiles from the walls. The same day, he learned from some prisoners captured in the sortie, of the undiminished spirit of the garrison, and that Hennebon was amply supplied with provisions brought by sea. His own army was becoming straitened by the scarcity of supplies in the country round, he therefore determined at once to raise the siege, and to besiege some place where he would encounter less serious resistance. Accordingly, next morning he drew off his army and marched to Carhaix. Shortly afterwards the news came that the Earl of Northampton and Robert of Artois, with their force, had sailed, and Don Louis, with the Genoese and other Italian mercenaries, started to intercept them with a large fleet. The fleets met off the island of Guernsey, and a severe engagement took place, which lasted till night. During the darkness a tremendous storm burst upon them and the combatants separated. The English succeeded in making their way to Brittany and landed near Vannes. The Spaniards captured four small ships which had been separated in the storm from their consorts, but did not succeed in regaining the coast of Brittany, being driven south by the storm as far as Spain. The Earl of Northampton at once laid siege to Vannes, and Sir Walter Manny moved with every man that could be spared from Hennebon to assist him. As it was certain that the French army would press forward with all speed to relieve the town, it was decided to lose no time in battering the walls, but to attempt to carry it at once by assault. The walls, however, were so strong that there seemed little prospect of success attending such an attempt, and a plan was therefore determined upon by which the enemy might be thrown off their guard. The assault commenced at three points in the early morning and was continued all day. No great vigour, however, was shown in these attempts which were repulsed at all points.