William Bowen, a native of Hannibal, Missouri, was SLC’s schoolmate and “First, & Oldest & Dearest Friend.” During an outbreak of measles in 1844, to end the suspense of waiting to catch the disease, SLC crawled into Bowen’s sickbed, was infected, and nearly died. By the spring of 1857 Bowen was a licensed steamboat pilot. After SLC received his own license, he was Bowen’s co-pilot twice in 1859. Despite early Southern sympathies, Bowen piloted a Union transport during the Civil War. He left the river in 1868 to sell insurance in St. Louis; he moved to Austin, Texas, about 1880. Twice married, Bowen suffered from poor health. Apart from a period of estrangement (1861–66), SLC and Bowen corresponded until a few years before Bowen’s death. Characters in several of Mark Twain’s writings are based or partly based on him, including Tom Sawyer and Joe Harper in Tom Sawyer and Huckleberry Finn.