Samuel Clemens was the real name of the famous writer Mark Twain. Twain grew up in Missouri in the years before the American Civil War. During this time. Missouri still recognized slavery as lagal. These conditions had a noticeable impact on Twain's writing. They can be seen in the themes dealt with in his novels. At the time of the Civil War. Twain was in his late twenties. He did not actually fight in the war. He lived in Nevada and California during the war years.