Charles was an exceptionally skilled military leader and tactician as well as an able politician, credited with introducing important tax and legal reforms. As for his famous reluctance towards peace efforts, he is quoted by Voltaire as saying upon the outbreak of the war; "I have resolved never to start an unjust war but never to end a legitimate one except by defeating my enemies". With the war consuming more than half his life and nearly all his reign, he never married and fathered no children. He was succeeded by his sister Ulrika Eleonora, who in turn was coerced to hand over all substantial powers to the Riksdag of the Estates and opted to surrender the throne to her husband, who became King Frederick I of Sweden.