Presidios
While the missions were the central frontier institutions of Spanish California, other institutions played important roles. Spanish officials established four presidios, or military forts, along the California coast.
Spanish colonial officials carefully chose the location for each of the California presidios. Several of the presidios were located near the entrances to the best ports, at locations where they could defend the harbors against foreign attack. Like the missions, the presidios also were placed in areas where supplies of fresh water were available.
The presidios were evenly distributed among the coastal missions. If an Indian revolt or attack occurred at a mission, the soldiers from one of the nearby presidios could be rapidly deployed to assist in defending the mission or pursuing and punishing the attackers.