California Battalion

The California Battalion (also called the first California Volunteer Militia and U.S. Mounted Rifles) was formed during the Mexican American War (1846–1848) in present-day California, United States. It was led by U.S. Army brevet lieutenant colonel John C. Fremont and composed of his cartographers, scouts and hunters and the California Volunteer Militia formed after the Bear Flag Revolt. The battalion's formation was officially authorized by Commodore , commanding officer of the U.S. Navy Pacific Squadron.

Hostilities between U.S. and Mexican forces had been underway in Texas since April 1846 resulting in a formal declaration of war on 13 May 1846, by the U.S. Congress. On 17 May 1846, unofficial word reached the U.S. Navy fleet of four vessels at anchor in the harbor of Mazatlán, Mexico, and that hostilities had begun between Mexico and the United States. Commodore John D. Sloat, commander of the U.S. Navy's Pacific Squadron, dispatched his flagship, the frigate USS Savannah, and the Sloop USS Levant to Monterey harbor where they arrived on 2 July 1846. The U.S. Navy's Pacific Squadron captured Monterey, California on 7 July 1846 and began taking over the ports in Alta California. The Bear Flag Revolt was converted into a U.S. occupation of California and the Bear Flag was replaced by the Stars and Stripes.

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