In 1217 Prince Louis and his allies, the barons, had been defeated at the battle of Lincoln, and, being now hemmed in between their enemies and the sea, were in urgent need of reinforcements from abroad. Stores and men were collected for them in Normandy. Eighty ships, besides smaller vessels, are said to have been brought together at Calais, under the command of Eustace the Monk. This man was one of the many mercenary fighters of the time, and had once been in the employment of King John. With this force he put to sea, running before a southerly wind. His intention was to round the North Foreland, and carry his convoy up the Thames to London, which was still held for the barons. If he had succeeded, he might have greatly prolonged the Civil War, but, happily for England, neither the man nor the means to avert the disaster were wanting. Hubert de Burgh, the King's Justiciary and Governor of Dover Castle, was at his post. He appealed to the men of the Cinque Ports, not in vain. "If these people land," he said, "England is lost; let us therefore boldly meet them, for God is with us, and they are excommunicate." Hubert de Burgh saw that the one effectual way of preventing Eustace from doing harm on shore was to beat him at sea before he could land. The man who reasoned like this had grasped the true principle of the defence of England. Sixteen large ships and some smaller vessels were lying in Dover harbour. They were at once got out by the shipmen and fishermen of the town, worthy ancestors of the men who, centuries later, volunteered to fill up the crews of Blake, when he was threatened by Tromp in these very waters. The knights, squires, and men-at-arms of Hubert de Burgh's following made up the fighting crews. Training the yards of the one great square sail which the vessels of that time carried on their single mast, fore and aft, the English squadron kept its luff (the word is used by Matthew Paris), and, standing out to the east, placed itself on the track of the Monk, and between him and Calais.