In 1769, he lead an expedition set out to establish a Spanish colony at Monterey Bay. The expedition's four parties met at San Diego Bay, where colony - the present-day San Diego - was established. De Portolá's land party initially didn't find the bay and returned to San Diego. A second expedition was set out, and Monterey Bay was finally reached on May 24, 1770. There, the mission of San Carlos was founded.