Peter accompanied his cousin, King Philip Augustus, on the crusade of 1190, fought against the Albigenses, and was present at the battle of Bouvines in 1214.
With his mercenaries behind him he met with some small successes in his fight for Normandy, but on the 27th of July he and his ally, the emperor Otto IV., met with a crushing defeat at Bouvines at the hands of Philip Augustus, and even the king himself was compelled to recognise that his hopes of recovering Normandy were at an end.
After Bouvines he purchased the assistance of Valdemar II., king of Denmark, by ceding to him a large stretch of land along the Baltic coast; and, promising to go on crusade, he secured his coronation at Aix-la-Chapelle in July 1215.
Philip now took the offensive himself, and in manoeuvring to get a good cavalry ground upon which to fight he offered battle (July 27), on the plain east of Bouvines and the river Marque - the same plain on which in 1794 the brilliant cavalry action of Willems was fought.
Enguerrand III., the Great, fought at Bouvines under Philip Augustus (1214), but later he was accused of aiming at the crown of France, and he took part in the disturbances which arose during the regency of Blanche of Castile.
The final blow to his fortunes came when he was decisively defeated by the French at Bouvines in July 1214.