On 27 July 1214, the forces of Otto IV of the Holy Roman Empire, King John I of of England, and Count Ferrand of Flanders were defeated by the forces of Philip II Augustus of France at the Battle of Bouvines.
Otto IV had come into conflict with Pope Innocent III over whether the right of conferring the crown of the Holy Roman Empire belonged to the pope alone. Innocent III claimed that the pope had the authority to decide whether a candidate chosen by the German princes to become Emperor was worthy of that dignity. While Innocent had initially supported Otto, they became opponents in 1210 after Otto decided to restore Imperial power in Italy. Innocent was greatly upset at this, believing that a Holy Roman Empire with the addition of Italian territories would be a threat to the Papal States. Innocent would excommunicate Otto and give his support to Frederick II Hohenstaufen as a rival claimant to the title of Holy Roman Emperor.
While the forces of John I and Otto IV [25,000] outnumbered those of Philip II [15,000], the French forces were more experienced – having fought in the Crusades. the three hour battle saw around 2,000 casualties and about 9,000 captured. Philip II was nearly killed in the battle after being de-horsed several times.
After the Battle of Bouvines, Otto IV would be forced to resign and Frederick II would become the new emperor of the Holy Roman Empire. John I would also be forced to sign the Magna Carta by his nobles.