S. C. Gwynne is an American nonfiction writer. He is the author of the prize-winning "Empire of the Summer Moon" and his latest book is called "Hymns of the Republic".S. C. Gwynne is an American nonfiction writer. He is the author of the prize-winning "Empire of the Summer Moon" and his latest book is called "Hymns of the Republic".S. C. Gwynne is an American nonfiction writer. He is the author of the prize-winning "Empire of the Summer Moon" and his latest book is called "Hymns of the Republic".