A lengthy, tenacious, fictional defense of the controversial career of John Charles FrÃ‰mont, ""The Pathfinder"" (1813-90), whose several wilderness expeditions to California in the 1840's are believed to have spurred the opening-up of the West; whose military leadership may (or may not?) have secured the US hold on California; who was the first California senator and the first Republican Party nominee for President; who was twice given a high command in the Civil War and twice removed; who possessed power and riches and ended his life in poverty. Dramatic material? Potentially. But first-novelist Nevin, in his determination to shake loose his hero from lingering charges of ""charlatan and braggart,"" has produced a pale, uncompelling FrÃ‰mont, a non-pareil of rectitude and courage who's always less commanding than the meticulously documented history around him. It is FrÃ‰mont's father-in-law, the powerful Missouri senator Thomas Hart Benton (once violently opposed to FrÃ‰mont's marriage to his daughter Jessie), who urges FrÃ‰mont to map the Oregon Trail after his first successful surveying journey under French map-maker Nicollet. Three times, then, FrÃ‰mont conquers the punishing terrain over the Rockies and Sierras--driving on frozen and starving men with his enthusiasm. The 1845 expedition has a decidedly political emphasis, since he has received (indirectly) a message from crafty President Polk: Americans in the Mexican-owned territory of California could do with a leader determined to hold off the British and Mexicans, but also a leader discreet enough to hold off the state-controlling ambitions of abolitionists and slave-owning Southerners. But FrÃ‰mont's success in carrying out his mission will be followed by betrayals and humiliations leading to a court-martial in Washington. And the last expedition is a disaster, with one third of his men lost, whispers of murder and cannibalism. Then the wheel turns, and gold is discovered on FrÃ‰mont's Mariposa ranch; he and Jessie will take a Grand Tour; on return FrÃ‰mont will be the new Republican Party's candidate for President. Later, however, his Civil War military career is blighted by the Army establishment--and Lincoln, who punishes him for jumping the gun on an emancipation proclamation. So, at the close of his life, his fortune gone, even his historic archives stolen, FrÃ‰mont and his feisty, loyal Jessie are given a trip westward on the railroad he'd hoped to build. Nevin, author of several volumes of popular history, does well with some of the issues, with some of the debates, and some of the presidents. (The Lincoln cameo is especially vivid.) But, though crammed with information, this massive reconstruction lacks the pep, character-appeal, and authentic period tones of genuinely dramatized historical fiction--most recently, for example, the more modest (but far more exciting) expeditions of Donald Jackson's Valley Men (p. 834).