During the Mexican War, the federal Army of the West was charged with occupying New Mexico and California. Led by Stephen Watts Kearny, the army divided strategically into units that separately conquered Santa Fe, Taos, and southern California territories, winning the entire region for the United States.
When the United States declared war on Mexico in May, 1846, the military strategy of President James K. Polk and his advisers was to occupy the capitals of the northern Mexican provinces and to march on Mexico City
Charles
On June 30, 1846, the Army of the West started for Santa Fe, following the Santa Fe Trail for eight hundred miles. The trail took them first to Bent’s Fort on the Arkansas River and then southward into New Mexico. On the outskirts of Santa Fe, Kearny learned that three thousand Mexicans under the command of Manuel Armijo, the governor of New Mexico, had occupied a strategic canyon through which Kearny’s men would have to pass.
Rather than risk a military clash, Kearny resorted to diplomacy, sending forward intelligence agent James Wiley Magoffin,
Disregarding his promise to Archuleta, Kearny issued a proclamation announcing the intention of the United States to annex the whole of New Mexico. He promised the residents a democratic government and a code of law, and he named Charles Bent
With the first phase of his campaign completed, Kearny continued his program by separating his army into three forces. One force he left behind in New Mexico to hold the province. Another force, composed of three hundred volunteers from Missouri under Colonel Alexander W. Doniphan,
Kearny, meanwhile, had taken the third force of three hundred dragoons out of Santa Fe on September 25, 1846, and headed for California. He was accompanied by Lieutenant William H. Emory
Kit Carson.
The division of Kearny’s force proved fortunate for the interests of the United States, because the detachment returning to New Mexico arrived in time to suppress the Taos
At the same time, the United States extended its authority to California. Before war had been declared between the United States and Mexico, Thomas O. Larkin, the U.S. consul in California, had hoped that he could effect a peaceful transfer of the Mexican province to the United States. Larkin’s hopes were dashed, however, by events surrounding John C. Frémont’s appearance in California between December, 1845, and June, 1846.
Frémont had secured permission from Governor José Castro (1810-1860)
The exact contents of these communications have remained unknown; however, after his encounter with Gillespie, Frémont returned to California, despite Castro’s order to leave, and made his way to the vicinity of Sonoma. There, in June, he immediately became involved in an uprising of settlers from the United States known as the Bear Flag Revolt
Frémont’s national reputation as a hero in the conquest of California waned when the Bear Flag Revolt was assessed against the efforts of Larkin to secure California peacefully for the United States, and when it was learned that the war with Mexico—which prescribed the U.S. conquest of California—had been declared before the Bear Flag Revolt took place. Critics have censured Frémont for having provocatively endangered relations between the United States and Mexico at a time when Frémont could not have known of the state of war. Historians point out that the Bear Flag Revolt had little importance in the U.S. conquest of California, because Commodore John Sloat’s first official act of conquest was to sail into Monterey Bay and raise the United States flag over the customs house on July 7, twelve days before Frémont’s arrival in Monterey.
Events of the Bear Flag Revolt
Territorial Growth of the United States
About that time, Commodore Robert Field Stockton
The American Southwest was now de facto in the hands of the United States. Diplomatic complications delayed the signing of the Treaty of Guadalupe Hidalgo until February, 1848, however, more than a year after the fighting in the northern Mexican provinces had ceased. As a result of the treaty, when it was finally signed, the United States acquired all or portions of the future states of California, Nevada, Utah, Colorado, New Mexico, and Arizona. All Native Americans and Mexicans living in those territories passed under the suzerainty of the United States. In addition to the long-term significance of this acquisition, the short-term significance of California’s annexation became apparent almost immediately, as gold had been discovered at John Augustus Sutter’s mill on the American River even before the treaty was signed.
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Chaffin, Tom. Pathfinder: John Charles Frémont and the Course of American Empire. New York: Hill & Wang, 2002. Well-written, comprehensive, and balanced biography, describing Frémont’s varied life and career. Includes information on his expeditions, relationships with allies and adversaries, and his marriage to Jessie Benton Frémont. -
Clarke, Dwight L. Stephen Watts Kearny: Soldier of the West. Norman: University of Oklahoma Press, 1961. The definitive biography of Kearny, a leading figure in the conquest of the Southwest. -
Eisenhower, John S. D. So Far from God: The U.S. War with Mexico, 1846-1848. New York: Random House, 1989. A survey of the Mexican War written for a popular audience. -
Harlow, Neal. California Conquered: The Annexation of a Mexican Province, 1846-1850. Berkeley: University of California Press, 1982. A thorough treatment of the economic, cultural, and physical conquest of California. -
Limerick, Patricia Nelson. The Legacy of Conquest: The Unbroken Past of the American West. New York: W. W. Norton, 1987. Argues that the conquest of land by the United States catalyzed social and economic interaction and fashioned the agenda for ongoing problems between subjugated peoples and the majority society. -
Mahin, Dean B. Olive Branch and Sword: The United States and Mexico, 1845-1848. Jefferson, N.C.: McFarland, 1997. Diplomatic history of the Mexican War that concentrates on the policies of the Polk administration. -
Roberts, David. A Newer World: Kit Carson, John C. Frémont, and the Claiming of the American West. New York: Simon & Schuster, 2000. An account of Frémont’s expeditions in the Western United States from the early 1840’s until the beginning of the Civil War. Describes Carson’s role in the expeditions and the relationship of the two men. -
Weber, David J. The Mexican Frontier, 1821-1846: The American Southwest Under Mexico. Albuquerque: University of New Mexico Press, 1982. An outstanding survey of the social, economic, and diplomatic realities of the old Mexican Cession and California.
Pike Explores the American Southwest
Santa Fe Trail Opens
Texas Revolution
Frémont Explores the American West
Mormons Begin Migration to Utah
Mexican War
California Gold Rush Begins
Treaty of Guadalupe Hidalgo Ends Mexican War
Gadsden Purchase Completes the U.S.-Mexican Border
Texas’s Cart War
Chisholm Trail Opens
Powell Publishes His Report on the American West
Kit Carson; John C. Frémont; James K. Polk; Brigham Young.