The war between the United States and Mexico had been declared on May 13, 1846, but this news was not known in California until mid-July 1846. However, in the face of rumors of an alleged action by the Mexican government against the settlers of American origin in the territory, a group of thirty-three armed men seized the city of Sonoma, flying a white flag with a bear and a star (the "bear flag") to symbolize the birth of the Republic of California, independent of Mexico.
That same day, June 14, the rebels captured the former Mexican commander of Northern California, General Mariano Guadalupe Vallejo, who was the leader of the military company stationed at the Sonoma Presidio. Sent to Fort Sutter, he was imprisoned on August 1, 1846.
The first and only president of the new Republic was the American pioneer William B. Ide, whose presidency lasted twenty-five days.
In April 1846, the beginning of the war being imminent, the federal government sent Colonel Rafael Tellez to the front of a large military body, very well equipped, to embark for Alta California and help defend the territory, much coveted by the United States. But upon arriving in Mazatlan, Tellez rebelled against President Mariano Paredes de Arrillaga and stayed in Sinaloa, where in complicity with foreign merchants he established a post in the southern part of the state and stole it from obedience to the local government. While this was happening, the US Pacific squad landed marines in Alta California (July 1846) which, after a violent struggle, managed to defeat the Mexican settlers, abandoned to their own forces, because in addition to Tellez revolted in Mazatlan, another detachment sent by Acapulco was retained in that region by the Native chief Juan Alvarez.
The Mexican governor, General Jose Castro, tried to stop the revolt and sent a detachment of 50 men against the rebels, but on June 23, 1846, the commander of the US Army John C. Fremont arrived with an army of sixty armed men, joined the "bear flaggers" and took command of the combined forces. The Mexican soldiers were defeated in the Battle of Olompali.
On July 7, a frigate and two sloops of the US Navy, under the orders of John D. Sloat, defeated the Mexican Coast Guard of the port of Monterrey, California, in a minor skirmish ( the Battle of Monterrey). This action indicated to Fremont that the war between Mexico and the United States had begun. In view of this fact, the "bear flaggers" abandoned the idea of creating an independent republic and joined the fight with the intention of incorporating California into the United States of America, as a sign of this new objective; They replaced the bear's flag with the American one. President Ide went from being the first magistrate of the republic to becoming a simple soldier of the "California Battalion", controlled by Fremont.
