In 1842, Army officer John Charles Frémont hired Carson to guide him on three separate expeditions into the West. All three expeditions involved mapping and describing remote and uncharted areas of the West. These expeditions were hugely successful. Frémont's reports to the government made Carson a frontier hero, and were read by many Americans. Carson became a celebrity throughout the United States. His adventures were turned into stories that were published in paper-covered books called dime novels. These cheap, popular books made him more famous than ever.