Born in Savannah, Georgia on January 21, 1813, John C. Fremont was the illegitimate child of the run-away wife of an older Revolutionary War veteran and a tutor who had fought with the Royalist in the French Revolution. In 1841 he married Jessie Benton, the daughter of Thomas Hart Benton, a powerful Mississippi senator and ardent proponent of Manifest Destiny, the philosophy that said America should control the continent from the Atlantic to the Pacific. As a Lieutenant in the Corps of Topographical Engineers in 1842 Fremont had already been part of several mapping expeditions west of the Mississippi and was now prepared to lead his first journey west when he met Kit Carson, an experienced mountain man and guide.
For the next several years Fremont mapped the Oregon Trail with Carson’s help. Eventually he arrived at Fort Vancouver on the Columbia River, then from Oregon he went south to Sutter’s Fort. His published journals would become the guidebooks for the wagon trains that rolled west uninterrupted in the summer of 1849, but in June 1845 he began his next trip west with 55 men handpicked for their expert marksmanship and Carson again as guide, and, instead of his stated goal of mapping the headwaters of the Arkansas River, he made straight for California’s Sacramento Valley. There he promised the American settlers to protect them when war with Mexico broke out. Toward this end he lent support to the Bear Flag Revolt and, when war did erupt in 1846, he formed the California Battalion from his sharpshooters and local volunteers, then marched south and took Santa Barbara on Christmas Eve. Los Angeles surrendered a few days later and the war in California was quickly over.
On January 16, 1847 Commodore Stockton appointed Fremont as Military Governor of California but a heated disagreement arose with General Kearny, commander of the recently arrived Army of the West, who claimed he had orders from the president stating he was to be governor. Fremont resisted strongly but on March 1st Kearny replaced him and ordered Fremont back to Fort Leavenworth, Kansas where he was arrested, brought to Washington for trial, and convicted of mutiny and disobeying a superior officer. President Polk, a political ally of Fremont’s father-in-law, commuted his sentence of a dishonorable discharge. Fremont resigned from the army and returned to California.