Conquest of California

The California Campaign (1846−1847), colloquially the Conquest of California or Conquest of Alta California by the United States, was an early military campaign of the Mexican–American War that took place in the western part of Mexico's Alta California Department, in the present-day state of California. The California Campaign was marked by a series of small battles throughout 1846 and early 1847.

When war was declared on May 13, 1846 between the United States and Mexico, it took almost three months for definitive word of Congress' declaration of war to reach the Pacific coast. U.S. consul Thomas O. Larkin, stationed in the pueblo of Monterey, was concerned about the increasing possibility of war and worked to prevent bloodshed between the Americans and the small Mexican military garrison at the Presidio of Monterey, commanded by José Castro.

United States Army Captain John C. Frémont, on a survey expedition of the U.S. Army Corps of Topographical Engineers with about 60 well-armed men, crossed the Sierra Nevada range in December 1845. They had reached the Oregon Territory by May 1846, when Frémont received word that war between Mexico and the U.S. was imminent.

On June 14, 1846, the Bear Flag Revolt occurred when some 30 rebels, mostly American immigrants, staged a revolt in response to government threats of expulsion and seized the small Mexican Sonoma Barracks garrison, in the pueblo of Sonoma north of San Francisco Bay. There they formed the California Republic, created the "Bear Flag", and raised it over Sonoma. Eleven days later, troops led by Frémont, who had acted on his own authority, arrived from Sutter's Fort to support the rebels. No government was ever organized, but the Bear Flag Revolt has become part of the state's folklore. The present-day California state flag is based on this original Bear Flag, and continues to display the words "California Republic."

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