The story of New Spain’s presidios is unique, and Tubac is one of the few sites where it can adequately be told. Tubac Presidio State Historic Park’s primary purpose is to preserve the ruins of the oldest Spanish Presidio site in Arizona, San Ignacio de Tubac, established in 1752. The cavalrymen were stationed at the Presidio to protect the settlers from Apaches and Seris, to control the Pima Indians and to further explore the Southwest. Juan Bautista de Anza III was the second commander and the person who organized and led an expedition to California that resulted in the founding of the city of San Francisco in 1776. The expedition included 240 colonists from Sinaloa and Sonora, 63 of whom were from Tubac. The colonists gathered over 1,000 head of livestock-cattle, horses, and mules at Tubac for the expedition.