On the 8th of April, 1213, Philip convoked, at Soissons, his principal vassals or allies, explained to them the grounds of his design against the King of England, and, by a sort of special confederation, they bound themselves, all of them, to support him.

One of the most considerable vassals, however, the sometime regent of France during the minority of Philip, Ferrand, Count of Flanders, did not attend the meeting to which he had been summoned, and declared his intention of taking no part in the war against England.

"By all the saints of France," cried Philip, "either France shall become Flanders, or Flanders France!" And, all the while pressing forward the equipment of a large fleet collected at Calais for the invasion of England, he entered Flanders, besieged and took several of the richest cities in the country, Cassel, Ypres, Bruges, and Courtrai, and pitched his camp before the walls of Ghent, "to lower," as he said, "the pride of the men of Ghent and make them bend their necks beneath the yoke of kings." But he heard that John Lackland, after making his peace with the court of Rome through acceptance of all the conditions and all the humiliations it had thought proper to impose upon him, had just landed at Rochelle, and was exciting a serious insurrection amongst the lords of Saintonge and Poitou.

At the same time Philip's fleet, having been attacked in Calais roads by that of John, had been half destroyed or captured; and the other half had been forced to take shelter in the harbor of Damme, where it was strictly blockaded.

Philip, forthwith adopting a twofold and energetic resolution, ordered his son Philip to go and put down the insurrection of the Poitevines on the banks of the Loire, and himself took in hand the war in Flanders, which was of the most consequence, considering the quality of the foe and the designs they proclaimed.