Gaspar de Portolá was appointed to lead an exploratory expedition to the California coast, motivated by the Spanish Crown's interest in expanding its territories and establishing missions. Departing from San Diego on July 14, 1769, Portolá was accompanied by a group of soldiers, missionaries, and settlers, marking the beginning of an ambitious journey. The group was tasked with finding the Port of Monterey, an area rumored to have favorable conditions for anchorage and future colonization. This mission was significant not only for its objectives but also for the broader geopolitical interests of Spain in North America at the time.

Throughout their journey, the party encountered numerous challenges, including harsh landscape, difficult weather, and limited supplies. They traveled north, making observations and notes that would contribute to cartography and geographic knowledge of the region. Portolá's group initially relied on indigenous guides, but tensions sometimes arose between the explorers and Native American tribes. As they continued northward, they reached the outskirts of present-day Monterey but were thwarted by the area’s fog, which obscure their target.

After ultimately failing to find the port, Portolá and his men explored the nearby surroundings, leading to important interactions with local tribes and securing vital information. The expedition set a precedent for future colonization efforts in California and informed Spain’s strategic planning to establish missions and presidios in the region.