Shortly afterward 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 vigor, however, was shown in these attempts, which were repulsed at all points. At nightfall the assailants drew off to their camp, and Oliver de Clisson, who commanded the town, suffered his weary troops to quit the walls and to seek for refreshment and repose. The assailants, however, did not disarm, but after a sufficient time had elapsed to allow the garrison to lay aside their armor two strong parties attacked the principal gates of the town, while Sir Walter Manny and the Earl of Oxford moved round to the opposite side with ladders for an escalade. The plan was successful. The garrison, snatching up their arms, hurried to repel their attack upon the gates, every man hastening in that direction. Sir Walter Manny with his party were therefore enabled to mount the walls unobserved and make their way into the town; here they fell upon the defenders in the rear, and the sudden onslaught spread confusion and terror among them. The parties at the gates forced their way in and joined their friends, and the whole of the garrison were killed or taken prisoners, save a few, including Oliver Clisson, who made their escape by sally-ports. Robert of Artois, with the Earl of Stafford, was left with a garrison to hold the town. The Earl of Salisbury, with four thousand men, proceeded to lay siege to Rennes, and Sir Walter Manny hastened back to Hennebon. Some of Sir Walter's men formed part of the garrison of Vannes, and among these was Sir John Powis with a hundred men-at-arms.