Captain John C. Frémont (1813-1890) was an American explorer, soldier, and the first (though unsuccessful) Republican Party candidate for the presidency in 1856.
With the help of his powerful father-in-law, Frémont secured the command of expeditions exploring the West, from the Des Moines River to the Rocky Mountains and Oregon, Nevada, and California country. In 1846, Frémont persuaded the local American residents in California to follow the Texans' example by establishing their own independent Bear Flag Republic at Sonoma. The short-lived experiment accomplished very little. After Stephen W. Kearny and Commodore Robert Stockton claimed California for the U.S. during the Mexican-American War, an argument ensued over who was in command; Frémont sided with Stockton, but the U.S. government sent orders siding with Kearny, who had Frémont arrested, court-martialed, and convicted. President Polk remitted the sentence, but the proud Frémont resigned from government service after that. After making millions from the discovery of gold and serving briefly as a Senator, he made an unsuccessful presidential run with the new Republican Party in 1856; the party shared his firm stance against slavery's extension into the West. Employing the slogan, "Free soil, free speech, free men, Fremont," he and the Republicans came closer than anyone had before to uniting the voters of the North and the West against the South. Frémont went on to command the Western Department of the Union Army during the Civil War but soon left that post. He lost his fortune trying to build a railroad to the Pacific in the 1870s.