When William Thornton Cornwell was born on 5 July 1835, in Orange, Indiana, United States, his father, Harrison Edward Cornwell, was 33 and his mother, Nancy Arterburn Cornwell, was 27. He married Mary Bridgett Gallahan on 6 December 1858, in Washington, Indiana, United States. They were the parents of at least 4 sons and 2 daughters. He lived in Louisville, Jefferson, Kentucky, United States in 1880 and Bewleyville, Breckinridge, Kentucky, United States in 1910. He died on 24 December 1913, in Breckinridge, Kentucky, United States, at the age of 78, and was buried in Campbellsburg, Washington, Indiana, United States.