In 1856, John C. Frémont—the famed "Pathfinder" of the American West—became the Republican Party's first presidential nominee on an anti-slavery platform. Five years later, now a Union general under President Lincoln, he sparked a national crisis by unilaterally declaring emancipation in Missouri. Drawing from extensive research, author John Bicknell masterfully chronicles the volatile relationship between these two leaders as they grappled with slavery, military strategy, and the future of the nation.