Pope Gregory VII and king Henry IV had quite a few complications between each other. Gregory took the radical reform into hand so that he, the pope, would be the one to appoint people to office not the king or other laymen.
Of course Henry saw this idea as absurd because the king had always appointed officials of the church, it was tradition. They both wanted the authority but finally Henry was out to a temporary stop. Pope Gregory excommunicated him therefore Henry really didn’t have any rule over the kingdom. He could not stand it so he pled for forgiveness for three days and was finally forgiven. Soon afterward Henry went back to his old bad ways and again was excommunicated. Henry did not take this kindly which led him to exile Pope Gregory. Later Gregory died in exile but was a great example to all popes to come.