Before the war between the United States and Mexico had begun, a group of American immigrants revolted against the centralization policies of President Antonio López de Santa Anna. These same policies had resulted in the earlier 1836 uprising in Texas and other ones in Mexico, which Santa Anna had successfully defeated. When war became likely between the United States and Mexico, U.S. Army Major John C. Frémont, who had arrived in California claiming to be on a mission to find a route to the Pacific (his mission officially was to find the source of the Arkansas River), began encouraging a rebellion among the Anglo-American settlers. As a result, thirty-three settlers in Sonoma declared a republic and raised a homemade flag with a bear and star (the "Bear Flag") to symbolize a new Californi