Charles XI of Sweden

Charles XI inherited the Swedish throne in 1660 as a four-year-old, his father Charles X Gustav freshly dead. Governors raised him until his coronation at seventeen, when Danish troops forced him straight into the Scanian War to hold Sweden's recently won lands. He fought them off and came home to a country in disarray - finances wrecked, politics neglected, systems fraying. For the next two decades he kept the peace and overhauled nearly everything: finance, commerce, the military, courts, church structure, schools. His only son, Charles XII, inherited a well-trained army and spent it in wars across Europe. The numeral itself is inflated: Charles IX had reached back to a mythological Swedish king-list in the early 1600s, so Charles XI was really the eighth King Charles, but the tradition stuck and Sweden still counts that way today.