A member of the Knickerbocker Group, James Fenimore Cooper was considered the most important U.S. novelist before Nathaniel Hawthorne. His Leatherstocking Tales is considered a classic. Cooper invented the modern sea novel. His novels normally are classified into six major groups: historical romances, wilderness novels, sea novels, novels with European settings, socio -political novels, and Littlepage Manuscripts. His non-fiction writing, not received anywhere nearly as well as his fiction, included travels books, a history of the U.S. Navy, and social criticism.