In 1840, Alta California and Baja California Territory were removed from the Diocese of Sonora to form the Diocese of Both Californias. Bishop Francisco Garcia Diego y Moreno, OFM, established his cathedra at Mission Santa Barbara, making the chapel the pro-cathedral of the diocese until 1849. Under Bishop Thaddeus Amat y Brusi, C.M., the chapel again served as a pro-cathedral, for the Diocese of Monterey and then the Diocese of Monterey-Los Angeles, from 1853 to 1876. It is for this reason that of all the California missions, only the chapel at Mission Santa Barbara has two matching bell towers. At that time, that particular architectural feature was restricted to a cathedral church.