The coalition, backed and funded by King John of England, aimed to crush the growing power of the French crown. Philip Augustus's cavalry and militia beat the allies on a Sunday afternoon, when medieval armies usually avoided fighting. Otto escaped, but the counts of Flanders and Boulogne were captured. The victory secured Philip's conquests of Normandy and Anjou from John, weakened Otto's hold on the empire and sent John home humiliated, helping bring on the baronial revolt that produced Magna Carta.
By 1214 Philip II, known as Philip Augustus, had taken Normandy and most of England's lands in northern France. King John of England organized a two-pronged counterattack: he landed in Poitou in the southwest while his allies, including his nephew Otto IV, Count Ferdinand of Flanders and Count Renaud of Boulogne, gathered in the north.
On July 27, the two armies met on a plain near the bridge at Bouvines. In the fighting, Philip was knocked from his horse by infantry with hooked weapons and was saved by his knights. Otto, too, lost his horse and fled the field. Renaud of Boulogne held out with a ring of pikemen until he was overwhelmed and captured. The fighting lasted about three hours.
The consequences reached across Europe. Philip returned to Paris in triumph with Count Ferdinand in chains. Otto lost his throne to Frederick II, a rival backed by Philip and the pope. John, whose southern campaign had also failed, went home out of money and prestige. Within a year his barons had forced him to seal Magna Carta at Runnymede.
Key people: Philip II of France, Otto IV, Ferdinand, Count of Flanders, Renaud of Dammartin