Mission San Luis Obispo de Tolosa was a Spanish mission founded by Fray Junipero Serra, O.F.M., first president of the California missions. It was the fifth in a chain of 21 missions stretching from San Diego to Sonoma, and it was built by the Chumash Indians living in the area. Its combination of belfry and vestibule is unique among California missions. In 1846 John C. Fremont and his California Battalion were quartered here while engaged in the war with Mexico.