El Presidio de Sonoma (1810) came after Mexican Independence and was the last presidio built in California. It was built to buffer Mexico from a possible Russian invasion from Fort Ross.
This particular presidio grew quickly and became the headquarters of the Mexican Army in California, while the Spanish presidios in Monterey, San Francisco, Santa Barbara, and San Diego all declined in importance after Mexican Independence. Not much of the presidio is left, the only buildings still standing are the Barracks and the Casa Grande, which are now part of Sonoma State Historic Park (SHP).
Remember in the Mission San Rafael Archangel post, I mentioned John Frémont and how during the Bear Flag Revolt, he managed to take Sonoma and declare California a free Republic?
It was across the street from the Barracks in Sonoma Plaza that John Frémont drove the Bear Flag into the ground and named California a free state. The Bear Flag is now the modern state flag of California and a replica of the original can be found in the Barrack building.
From the barracks:
The original Bear Flag was made in the Sonoma Barracks on June 14 or 15, 1846. It flew over Sonoma until July 9, 1846 when it was replaced by the Stars and Stripes. Other Bear Flags – four or more of them – were made between June 15 and July 9 for use at Bodgea Bay and elsewhere.
When the original Bear Flag was lowered at Sonoma July 9, it was given as a memento to one of the sons of Captain Montgomery of the U.S.S. Portsmith then at anchor in San Francisco Bay. Montgomery took the flag to Washington D.C. where it was placed in the archives of the Naval Department. In 1855, at the request of California’s Congressional delegation, the flag was returned to California for permanent display in the San Francisco headquarters of the Society of California Pioneers.
The flag on display here is a copy made by the Pioneers before the original flag was destroyed in the San Francisco earthquake and fire of 1906.