In 1769, Spain feared it was about to lose the Pacific coast. Russian traders were moving south from Alaska, British naval power was rising, and Spain had no permanent settlements north of Baja California. In response, imperial officials launched a land-and-sea operation known as the Sacred Expedition — a march that would found San Diego, search for the lost harbor of Monterey, and lead a small overland party to the first recorded European sighting of San Francisco Bay. The Portolá Expeditio...