Battle of Bouvines
He was present in 1198 at Philip's coronation at Mainz, and supported him till his victory was assured. After Philip's murder in 1208, he "said and sang" in support of Otto of Brunswick against the papal candidate Frederick of Hohenstaufen; and only when Otto's usefulness to Germany had been shattered by the Battle of Bouvines (1214) did he turn to the rising star of Frederick, now the sole representative of German majesty against pope and princes.