Troops from the first Fort Buchanan built it in May 1860 at the confluence of the San Pedro River and Aravaipa Creek. Its purpose was to protect area settlers and emigrants against hostile Indians and was first called Fort Arivaypa, but it was soon changed to Fort Breckinridge, in honor of Vice President John C. Breckenridge. In February 1861, Fort Breckinridge troops reinforced Fort Buchanan troops during the hostilities associated with the Bascom Affair at Fort Bowie.
In July 1861, after the outbreak of the Civil War, the area faced a Confederate invasion from Texas and the Army abandoned and burned Fort Breckinridge, as well as other posts in southern Arizona, to keep them out of Confederate hands.
In May 1862, the fort was rebuilt by the California Volunteers and renamed Camp Stanford for Governor Leland Stanford of California. However, a few months later, in October, it was renamed back to Fort Breckenridge. The post was again destroyed by federal forces in July 1865 to keep supplies out of Confederate hands.
But, with the Civil War over and Indian attacks increasing, the fort was again rebuilt in November 1865 by the 2nd California Infantry. This time, it was named Fort Grant in honor of Union hero, General Ulysses S. Grant. The California Volunteers were replaced by regular troops in March 1866.
Later that year, the post was destroyed again, this time by flooding. The troops then moved to an upper terrace on the east bank of the San Pedro River and the fort was re-designated as a camp, rather than a fort. The troops were kept busy fighting hostile Apache, who were prone to making raids on area settlers.
In early 1871, when Pinal and Arivaipa Apache requested sanctuary near the fort, they were allowed to hunt and farm the area and start a camp nearby. Unfortunately, during this time, other Apache bands continued to raid the territory and though unfounded, many settlers blamed those bands living near Camp Grant. On April 30, 1871, a mob of angry citizens from Tucson and their Papago Indian mercenaries clubbed, shot, and mutilated 144 Aravaipa Apache people, mostly women, and children near Camp Grant. Known as the Camp Grant Massacre, their actions were taken in “retaliation” for a Gila Apache raid in which six people had been killed and some livestock stolen.
A temporary Indian Reservation was then established near Camp Grant, but in 1872, it was moved to San Carlos. Afterward, a new Fort Grant was established at the base of Mount Graham which was more strategically located to fight the still hostile Apache. Old Camp Grant was abandoned in March 1873.
The site today is situated near the Aravaipa Campus of the Central Arizona Community College between the towns of Mammoth and Winkelman on Arizona State Route 77. There are no remains.