 He ascended the throne of France upon the death of his brother Francis II in 1560.After decades of tension, war broke out between Protestants and Catholics after the massacre of Vassy in 1562.In 1572, after several unsuccessful peace attempts, Charles ordered the marriage of his sister Margaret of Valois to Henry of Navarre (the future King Henry IV of France), a major Protestant nobleman who was in the line of succession to the French throne, in a last desperate bid to reconcile his people.