Cotton's 15 nonconsecutive manuscript pocket diaries for the period from 1850 to 1877. The diaries outline his life and travels. The entries for the Civil War years are especially interesting. He often describes the capital's fear of enemy invasion, recent nearby incursions, troop movements, and the general preoccupation with all aspects of the war. He called on President Lincoln, attended his second inauguration, and notes the passage of the Emancipation Proclamation. He describes the capital's joyous mood at the fall of Richmond and the gloom over the assassination of Lincoln. He attended the military court to see the conspirators. Later volumes talk about Pension Bureau affairs and his health and that of his family.