The Mexican War and California
The American Conquest: Manifest Destiny Realized
by Justin Ruhge
The year 1846 saw the realization of the American plan of manifest destiny to conquer and include the entire North American continent to the Pacific Ocean under one government and one flag. Mexico's 24 years of internal strife since its revolution weakened its northern possessions and made the Mexican citizens in Northern California disgusted with its petty revolutions and inane leaders sent from Mexico City 3,000 miles away with nothing but mule track roads connecting the northern possessions to the south.
Mexico was very aware of the desires of the United States to possess the California territory with its 25,000 inhabitants. Offers to purchase first San Francisco and then the whole territory of Alta California were rejected ten years earlier by the Mexican government. The premature landing of the American Navy at Monterey in 1842 was a clear message of the resolve and readiness of the eastern government to act. The American Navy could put more men on shore in one landing than were garrisoned at all of the Mexican presidios.
The Monroe Doctrine of 20 years earlier had warned European powers away from coveting this territory. So, on July 1,1846, the long anticipated event happened. The Pacific Squadron appeared off the Alta Mexico capital of Monterey and on July 7 landed naval forces that raised the American flag there to start the occupation and conquest of the soon-to-become great State of California.
For months the Pacific Fleet and the British Pacific squadron had been shadowing each other to anticipate each other's intentions. The Americans had been waiting off Mazatlan, Mexico for the rumored declaration of war against Mexico. When this finally came, the American squadron sailed for Monterey to claim California before the British could do so. Historians have argued this issue afterwards but there was a feeling at the time that the British might step in to take California.
The Navy took the initiative to raise the flag at key spots in California, first at Monterey, then landing at San Pedro and marching to Los Angeles and on to San Diego. Occupying forces were also sent to Sonoma, Sutter's Fort and the Smith Ranch at Bodega Bay. Lieutenant John Fremont and his American Topographical Engineers were the only land forces in the area at the time. Late in 1846, the Army appeared in the form of General Kearny and his column of Army troops from Santa Fe, New Mexico.
In 1847 the First New York Regiment of Volunteers arrived to help occupy the State and to send troops to occupy Cabo San Lucas, San Jose del Cabo, and La Paz in Baja California; and Guaymas, San Blas and Mazatlan on the Mexican mainland.
The details of the occupation and the ensuing battles with the Mexicans have been thoroughly presented by H. H. Bancroft in his History of California for the years 1846 to 1848 and need not be presented here further except as background for the main discussion of the forts and facilities established by the occupying Americans. Numerous other works have been prepared by those present at the events in those years and are listed in the Bibliography of this history. The main effort in this section of this work is to describe the permanent and temporary forts and installations prepared by the Americans on their arrival.
When the Americans arrived, they brought with them their military bureaucracy the likes of which the Mexicans had never seen. The Americans changed everything to their way of thinking, overnight. California became an American base, first with temporary fortifications then with more permanent installations. The Army was the government of occupation that provided the law and order to the new territory. In 1849, after a constitutional convention was held in Monterey, and a civil government was elected, the Army turned over control of the State to the California representatives and quickly faded into the background.



Monterey's Presidio Occupied and Improved
The Americans Land at Yerba Buena
The Occupation of Santa Barbara
The Battle of Los Angeles
Occupation of San Diego and the Founding of Fort Stockton
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Updated 23 June 2017