Situated at the confluence of the San Pedro River and Aravaipa Creek, the location of Camp Grant was the home of the Arivaipa Apache before they had been driven from it by white settlers. In February 1871, five starving old Aravaipa women came to the camp under a flag of truce asking for sanctuary, which Lieutenant Royal Emerson Whitman granted. Before long, over 500 Aravaipa, under Chief Eskiminzin, had gathered in the area, asking that they be allowed to grow crops along the creek to feed their people. This was allowed, and Whitman also arranged for them to “earn their keep” by working as farmhands for the local ranchers and extracting a promise from them that none of the tribe would participate in any raids.
However, other Apache bands continued their raids at this time, many of which were blamed on the Aravaipa at Camp Grant. On April 30, 1871, an angry mob of citizens from Tucson and their Papago Indian mercenaries attacked the Aravaipa camp, clubbing, shooting 144 people, mostly women and children. All but eight of the corpses were women and children, as the men had been off hunting in the mountains. The attack was made in retaliation for a Gila Apache raid in which six people had been killed and some livestock stolen. Twenty-seven children who were captured were sold in Mexico by the Papago Indians.
After the massacre, a trial was demanded by President Ulysses S. Grant, who threatened to put the state under martial law if the Governor failed to act. However, at the trial that occurred later in the year in Tuscon, Arizona, the jury took just 19 minutes to acquit more than 100 defendants named in the attack.