Finally on 30 May 1518, when the Pope demanded an explanation, Luther wrote a summary and explanation of his theses to the Pope. While the Pope may have conceded some of the points, he did not like the challenge to his authority so he summoned Luther to Rome to answer these. At that point Frederick the Wise, the Saxon Elector, intervened. He did not want one of his subjects to be sent to Rome to be judged by the Catholic clergy so he prevailed on the Holy Roman Emperor Charles V, who needed Frederick's support, to arrange a compromise.