Frontier military outposts in Arizona began with several early presidios established along the Santa Cruz River.
Presidio San Ignacio de Tubac was founded in June 1752 after a Pima uprising that threatened Spanish silver mining interests around Arivaca and the Santa Rita Mountains, including the Alto, Salero, Montosa and Wandering Jew mines worked by Jesuit missionaries from Tumacácori in 1688.
Presidio San Augustin del Tucson was founded in 1775 as Spaniards broadened the need to protect their mining interests in the Santa Catalina Mountains, including the Iron Door Mine and La Esmeralda Mine.
That same year, Presidio Santa Cruz de Terranate (1775-80), with a perimeter of 100 square meters, was established by Spanish troops along the San Pedro River in a failed effort to expand Spanish holdings and broaden their quest for metals. Spanish influence in the region evaporated with Mexico’s independence from Spain in 1821.
The outcome of the Mexican War (1846-48) and subsequent Gadsden Purchase of 1853 affirmed the United States’ commitment of protecting its citizenry and fulfilling the country’s “Manifest Destiny” in the Southwest.
During the latter half of the 19th century, the U.S. military was obliged to protect mining and ranching interests in Arizona territory from the Native Americans.
After the Civil War, the U.S. Army considered Arizona its most dangerous assignment because of the high rate of casualties among military personnel and civilians in the territory.
More than 46 camps and forts were established within the territory. Many of them were established for strategic purposes. Thousands of miners passed through Arizona on their way to the California Gold Rush of 1849, initiating the creation of Fort Yuma to control the raiding parties of Yuma Indians.
Additional forts followed: Fort Defiance (1851-61), established in the Four Corners area, tracked the activities of the Navajo. Relatively unexplored central Arizona was opened to mining with the arrival of the Walker and Weaver exploratory parties in 1862-63 to the Prescott Basin.
Upon discovery of gold in the Bradshaw Mountains area including Rich Hill, Lynx Creek, Granite Creek and Turkey Creek, Fort Whipple (1864-1913) was built to offer protection to the miners.
Fort Buchanan (1856-61) operated between Patagonia and Sonoita. Fort Crittenden (1867-73) was later established nearby, consisting of several company quarters, a guardhouse, hospital, commissary, storehouse and corrals.
Buildings were manufactured of adobe, with mud roofs. Both forts helped protect silver mining interests in the Patagonia and Santa Rita mountains.
Camp Picket Post (1870s), named for nearby Picket Post Mountain, protected the mining village of Pinal as its population peaked at 2,500 because of the nearby Silver King Mine.
Fort Mojave (1859-90), on the east bank of the Colorado River, was garrisoned by California volunteers to protect the Mojave Road, a supply line for miners to the gold discoveries in the creeks in the Agua Fria River Basin near Prescott.
Fort Bowie (1862-94) became one of the most significant military outposts in Arizona — Geronimo and his forces were held there before being moved to Alabama and Florida.
Mining operations, including in Bisbee and Morenci, flourished following the culmination of Apache hostilities in Arizona after Geronimo’s surrender Sept 4, 1886. Through the efforts of Spanish and U.S. forts, the Arizona frontier was secured for mining operations.