Meanwhile John, leaving his barons to discuss and formulate their grievances, pushed on with a great scheme of foreign alliances, by which he hoped to crush Philip of France, even though the aid of the feudal levies of England was denied him. He leagued himself with his nephew the emperor Otto IV. (his sister's son), and the counts of Flanders and Boulogne, with many other princes of the Netherlands. Their plan was that John should land in Poitou and distract the attention of the French by a raid up the Loire, while the emperor and his vassals should secretly mobilize a great army in Brabant and make a sudden dash at Paris. The scheme was not destitute of practical ability, and if it had been duly carried out would have placed France in such a crisis of danger as she has seldom known. It was not John's fault that the campaign failed. He sent the earl of Salisbury with some of his mercenaries to join the confederates in Flanders, while he sailed with the main body of them to La Rochelle, whence he marched northward, devastating the land before him. Philip came out to meet him with the whole levy of France (April 1214), and Paris would have been left exposed if Otto and his Netherland vassals had struck promptly in. But the emperor was late, and by the time that he was approaching the French frontier Philip Augustus had discovered that John's invasion was but a feint, executed by an army too weak to do much harm. Leaving a small containing force on the Loire in face of the English king, Philip hurried to the north with his main army, and on the 27th of July 1214 inflicted a crushing defeat on the emperor and his allies at Bouvines near Lille. This was the greatest victory of the French medieval monarchy. It broke up the Anglo-German alliance, and gave the conqueror undisturbed possession of all that he had won from the Angevin house and his other enemies. Magna Carta.