King Frederick VII of Denmark was married three times, but produced no legitimate issue. The fact that he reached middle age without producing an heir meant that Prince Christian of Glücksburg (1818–1906), the descendant of a cousin of King Frederick VI, was chosen as his heir-presumptive in 1852. When Frederick died in 1863, Christian took the throne as Christian IX. I wonder, what if crown prince Karl (Charles in English) of Sweden and Norway (the later king Karl (XV in Sweden, IV in Norway) had been chosen instead? Would this be a possible alternative? If so he would later have been king of all the three Scandinavian countries.