<P> After ushering in the period of organized emigration to California, Marsh helped end the rule of the last Mexican governor of California, thereby paving the way to California's ultimate acquisition by the United States . </P> <P> In 1846, a group of American settlers in and around Sonoma rebelled against Mexican rule during the Bear Flag Revolt . Afterwards, rebels raised the Bear Flag (featuring a bear, a star, a red stripe and the words "California Republic") at Sonoma . The Republic's only president was William B. Ide, who played a pivotal role during the Bear Flag Revolt . This revolt by American settlers served as a prelude to the later American military invasion of California, and was closely coordinated with nearby American military commanders . </P> <P> The California Republic was short lived; the same year marked the outbreak of the Mexican--American War (1846--48). When Commodore John D. Sloat of the United States Navy sailed into Monterey Bay and began the military occupation of California by the United States, Northern California capitulated in less than a month to the United States forces . After a series of defensive battles in Southern California, the Treaty of Cahuenga was signed by the Californios on January 13, 1847, securing American control in California . </P> <P> Following the Treaty of Guadalupe Hidalgo (February 2, 1848) that ended the war, the westernmost portion of the old Mexican territory of Alta California soon became the American state of California, and the remainder of the old territory was then subdivided into the new American Territories of Arizona, Nevada, Colorado and Utah . The lightly populated and arid lower region of old Baja California remained as a part of Mexico . In 1846, the total settler population of the western part of the old Alta California had been estimated to be no more than 8,000, plus about 100,000 Native Americans, down from about 300,000 before Hispanic settlement in 1769 . </P>

When did california become part of the usa