In the Netherlands Sir William Lockhart admirably supplied the place of Sir John Reynolds, acting both as ambassador and general. The Allied army opened the campaign of 1658 with the siege of Dunkirk. The Prince of Condé had in vain assured the Spaniards that this would be the case, whilst they imagined that the intention of the Allies was to besiege Cambray. When Don John saw his mistake, he determined to attack the Allies and raise the siege. But Turenne and Lockhart would not wait to be attacked; they marched to meet the Spaniards, and surprised them before they had received their supply of ammunition for the intended assault. Don John hastily drew up his forces along a ridge of sandhills, and gave the command of the right wing to the Duke of York, and the left to Condé, himself commanding the centre. Lockhart was too ill to take the command, but gave it to Colonel Morgan, who, with his English forces, found himself opposed to the Duke of York. The English dashed up the sandhill, and soon drove the infantry of the enemy before them. They were then charged by the Duke of York at the head of the Spanish cavalry, and the battle was terrible, but nearly half of the duke's men fell under the well-directed fire of his countrymen. The left wing, however, under Condé, had given way, and the duke, leaving his rallied infantry to contend with the English in front, directed the charge of his cavalry against their flank. It was in vain; the centre gave way without fighting, and the brave English defending themselves against their numerous assailants till relieved by a body of French horse, the whole line of the Spaniards collapsed. The Duke of York, who had fought gallantly, was saved in the first charge only by the temper of his armour, and in the second he was surrounded by the enemy, and, according to his own account, only extricated himself by assuming the character of a French officer, and leading on several troopers to the charge till he saw a chance of riding off. Marshal Turenne gave the credit of the victory to the gallantry of the English, who had, at the close of the battle, scarcely a single officer left alive. At Whitehall the victory was attributed to the prayers of the saints at Court, for it happened that the Protector had set apart that day for a solemn fast, and, says Thurloe, "whilst we were praying, they were fighting, and the Lord gave a signal answer." The Lord Falconberg was despatched to carry congratulations to Louis XIV., who was at Calais, and soon afterwards these were returned by the Duke of Crequi and M. Mancini, the nephew of Mazarin, who expressed his regret that, owing to the urgency of affairs, he was unable to come himself, as he said he had long desired; but he sent a magnificent sword from the king, and a fine piece of tapestry from himself. Dunkirk was given up to the English, Gravelines was taken, Ypres surrendered, and all the towns on the banks of the Lys fell into the hands of the conquerors.