On the Northeastern side of Sonoma's city hall you will find the statue for the Bear Flag Revolt, commemorating Sonoma as the birthplace of the short-lived California Republic. 

California was first under Spanish and then under Mexican rule (easy to be seen in many historic names between San Diego and Sonoma) before the bear flag was raised on June 14, 1846, by some 30 settlers, mostly American citizens. They staged a revolt, seized the Mexican garrison and created the California Republic that lasted no longer than a week before the U.S. Army took over on June 23. 

 The California state flag today is based on this original Bear Flag and still contains the words, "California Republic."