A Copperhead was a Northerner who sympathized with the South during the Civil War. The integrity of Abner Beech, the Copperhead of the title, and the pressures upon him, are the subjects of the novel. Beyond the main theme and plot, however, is the impact of the events on the young narrator, Jimmy, and how they change him. Jimmy matures during the course of the novel, as he learns that human motivation is not as simple or obvious as it might appear. The importance of public opinion and its power stand over the book like a shadow. In those days of intense and bitter political convictions and violent tempers, the gossip at the general store and post office could lead to disastrous consequences. Jimmy sees all of this and, young though he is, understands the significance of it. In a simple, unpretentious narrative, he conveys this to the reader.
Technically, the novel is an impressive achievement, a first person narration told by a character who does not participate in the main action, and yet a book with great sweep and dramatic power. The novel is perfectly designed and flows effortlessly from beginning to end, building to a dramatic climax and then settling into a brief denouement. The tone is controlled, with no sense of hysteria or undue passion, although the book deals with irrational and hotheaded individuals. Harold Frederic has maintained such an even tone that perhaps the narrative might even seem too dispassionate. Certainly, he leaves the conclusions of the story to the reader.
In its modest way, this novel is as perfect as ETHAN FROME and THE GREAT GATSBY. In less than two hundred pages, it encompasses a world and finally transcends it. Frederic is writing about honor and morality in this story of the civilian side of the Civil War and about the beauty of ordinary things in a violent world. Although Harold Frederic deplores the irrationality of society in time of stress, the true significance of the theme lies in the thought that it is impossible properly to judge, much less condemn, a man for his political views unless one comes to understand the personal motivations of the man himself. The local descriptions are vivid, and a sense of realism is carried by the heavily flavored dialects and regional locutions of the farmers who live in the community of Four Corners.