Meanwhile, a dangerous confederacy was forming on the Continent among the adherents of William of Normandy. Henry had neglected, in almost every instance, to perform the promises which he had made to the Norman barons; and he had refused to conclude the match which had been agreed upon between his son William and the daughter of Fulk, Count of Anjou. Louis of France, who still extended his favour and support to the son of Robert, entered into a league with Fulk of Anjou and Baldwin of Flanders, for the purpose of wresting the dukedom of Normandy from the possession of Henry. The first campaign was favourable to the arms of the English king, who successfully defended his territory against the attacks of the allies. Louis then determined to demand the assistance of the ecclesiastical power. A council of the clergy was convoked at Rheims, at which the Pope, Calixtus II., was present; and thither the King of France carried the young prince, and presenting him to the council, craved its assistance on his behalf. Louis addressed an eloquent speech to the Pope, in which he dwelt upon the unjust and merciless character of the King of England, who not only refused to his nephew those possessions which belonged to him of right, but also retained his brother, the Duke of Normandy, in solitary and endless imprisonment. Henry, who had been apprised of the purpose of the council, sent costly presents to the Pope and the clergy, and subsequently had an interview with Calixtus, at which similar inducements were employed with success. The council looked coldly on the suit of Louis, and refused him the assistance he demanded. The friends of William of Normandy continued the war with vigour, and Henry experienced several reverses. At the siege of Eu, Baldwin, Count of Flanders, the most energetic and determined of the allies, was killed; and finding himself thus freed from one formidable foe, Henry determined to get rid of another by means which, on a former occasion, had proved efficacious. He sent messengers to the Count of Anjou, proposing that the marriage between his son and the count's daughter should take place immediately; a bribe of money was also added. The count accepted the terms, withdrew his forces from those of the King of France, and the marriage was soon afterwards celebrated. The cause of the allies now rapidly lost ground. The less powerful barons, wearied with the ill success of their arms, or induced by presents, which were distributed with a lavish hand by Henry, deserted one after the other, until the French king was left to sustain the struggle almost alone. During the desultory warfare which was carried on between the opposing forces, an engagement took place which has been honoured with the title of the battle of Brenneville, and which has been cited as a curious example of the mode of warfare common at that time.