John of England now hastily reconciled himself to Innocent, at the price of the independence of his kingdom.  He thus became in a better position to aid his excommunicated nephew, and revenge the loss of Normandy and Anjou on Philip Augustus.  His plan was now a twofold one.  He himself summoned the barons of England to follow him in an attempt to recover his ancient lands on the Loire.  Meanwhile, Otto and the Netherlandish lords were encouraged, by substantial English help, to carry out a combined attack on France from the north.  The opposition of the English barons reduced to comparative insignificance the expedition to Poitou, but a very considerable army gathered together under Otto, and took up its position in the neighborhood of Tournai.  Among the French King’s vassals, Ferrand, Count of Flanders, long hostile to his overlord Philip, and the Count of Boulogne fought strenuously on Otto’s side; while, of the Imperial vassals, the Count of Holland and Duke of Brabant (Lower Lorraine) were among Otto’s most active supporters.  A considerable English contingent came also, headed by Otto’s bastard uncle, William Longsword, Earl of Salisbury.  Philip himself commanded the chivalry of France, leaving his son Louis to fight against John in Poitou.  On July 27th the decisive battle was fought at Bouvines, a few miles southwest of Tournai.  The army of France and Church gained an overwhelming victory over the league which had incurred the papal ban, and Otto’s fortunes were utterly shattered.  He soon lost all his hold over the Rhineland, and was forced to retreat to the ancient domains of his house in Saxony.  His remaining friends made their peace with Philip and Frederick.  The defection of the Wittelsbachers lost his last hold in the south of Germany, and the desertion of Valdemar of Denmark deprived him of a strong friend in the North.  John withdrew from Continental politics to be beaten more decisively by his barons than he had been beaten in Poitou or at Bouvines.

Frederick II, was now undisputed King of the Romans, and Innocent III had won another triumph.  By the Golden Bull of Eger (July, 1213) Frederick had already renewed the concessions made by Otto to the Church, and promised obedience to the holy see.  In 1216 he pledged himself to separate Sicily from the Empire, and establish his son Henry there as king, under the supremacy of the Church.  But, like his other triumphs, Innocent’s victory over the Empire was purchased at no small cost.  For the first time, a German national irritation at the aggressions of the papacy began to be distinctly felt.  It found an adequate expression in the indignant verses of Walther von der Vogelweide, protesting against the priests who strove to upset the rights of the laity, and denouncing the greed and pride of the foreigners who profited by the humiliation of Germany.