The conflict was decided by the Battle of Bouvines on 27 July 1214, which pitted Otto, allied to King John of England against Philip II Augustus. Otto was defeated by the French and thereafter lost all influence. He died on 19 May 1218, leaving Frederick II the undisputed emperor. Meanwhile, King John was forced to acknowledge the Pope as his feudal lord and accept Stephen Langton as Archbishop of Canterbury. In his turn, Frederick II would later become a bitter opponent of the papacy once his empire was secure.