John C. Fremont Enters California

Although the United States declared war against Mexico on May 13, 1846, it took almost two months (until the middle of June, 1846) for definite word of war to get to California.

American consul Thomas O. Larkin, stationed in Monterey, on hearing rumors of war tried to keep peace between the States and the small Mexican military garrison commanded by José Castro. U.S. Army captain John C. Frémont, with about sixty well-armed men, had entered California in December, 1845, and was marching slowly to Oregon when he received word that war between Mexico and the U.S. was imminent and so began his chapter of the war, the "Bear Flag Revolt".

John Charles Frémont (January 21, 1813 – July 13, 1890), was an American military officer, explorer, the first candidate of the Republican Party for the office of President of the United States, and the first presidential candidate of a major party to run on a platform in opposition to slavery. During the 1840s, that era's penny press accorded Frémont the sobriquet The Pathfinder, which remains in use, sometimes as "The Great Pathfinder".