Depicting the events from the wars with the Native Americans out West makes Bret Harte a writer of regional realism.
Realism, sometimes refered to as naturalism, in the arts is generally the attempt to represent subject matter truthfully, without artificiality and avoiding artistic conventions, or implausible, exotic, and supernatural elements.
Bret Harte was an American short-story writer and poet, best remembered for his short fiction featuring miners, gamblers, and other romantic figures of the California Gold Rush.