Joseph Conrad is one of the most prominent post-Civil War writers to work with themes that have become associated with modernism. His short novel, Heart of Darkness, is concerned with notions of subjective truth, the individual's relationship to history, alienation, social science, and the fragility of narrative truth.
Many critics consider the book a literary bridge between the nineteenth and twentieth centuries and a forerunner both of modern literary techniques and approaches to the theme of the ambiguous nature of truth, evil, and morality.
Beyond Conrad, we might also look at playwright Eugene O'Neill who wrote works using new techniques of narrative, including stream-of-consciousness. In addition to experimental structure, O'Neill shared themes of modern psychology in his work with the works of the modernist period.
The ideas of Freudian psychoanalysis were contemporary throughout O’Neill’s career, and the power of the unconscious suited his characters well.
These two literary figures offer us a prelude to the works and themes of modernism. Theodor Dreiser and Thornton Wilder are two more writers whose work predicts the themes of modernism in structure and content, though their work was less direclty relatable to modernism than the work of Conrad and O'Neill.