On the morning of April 30, 1871, a party of six Anglo Americans, 48 Mexican Americans, and 92 Tohono O'odham attacked an encampment of Aravaipa and Pinal Apache people along Aravaipa Creek near Camp Grant, in Arizona Territory. The Apaches at the camp had surrendered to the U.S. Army earlier that year and were living under an arrangement established by First Lieutenant Royal Emerson Whitman, the post commander, who had begun feeding and sheltering Apache bands that came to Camp Grant seeking safety. By spring 1871, nearly 500 Aravaipa and Pinal Apache, including Chief Eskiminzin, were camped near the post, cutting hay and working local fields.
Tensions had been building among Tucson-area settlers, some of whom formed a vigilante group, the Committee of Public Safety, led by William S. Oury and Jesús María Elías, blaming regional raids on the Camp Grant Apache. After a raid on livestock near San Xavier in April 1871, Elías and Oury organized an armed party that marched to Aravaipa Canyon and surrounded the Apache camp at dawn. Most Apache men were away hunting at the time. Tohono O'odham fighters carried out most of the direct attack while Anglo and Mexican American participants targeted those attempting to flee. A total of 144 Aravaipa and Pinal Apache were killed; all but eight of the dead were women and children, and most bodies were scalped. Twenty-nine Apache children were captured, and 27 of them were sold into slavery in Mexico; two escaped and returned to relatives.
In the aftermath, Whitman searched for survivors, buried the dead, and sent word to Apache men in the mountains that soldiers had not participated in the attack. Many local settlers viewed the killings as justified. Word reached the press and U.S. military leadership, who described the event as a massacre. President Ulysses S. Grant threatened to impose martial law on Arizona Territory if the perpetrators were not tried. In October 1871, a Tucson grand jury indicted 100 people on 108 counts of murder; the trial that December ended in a not-guilty verdict after 19 minutes of jury deliberation.
Following the massacre, Apache survivors sought unsuccessfully to recover the abducted children; officials located only six of the 27 taken, and no records survive documenting the fate of the rest. In 1873, fear of further violence led many Aravaipa and Pinal survivors to relocate to the San Carlos Reservation. Some returned to Aravaipa Canyon in 1877, but renewed threats of mob violence in 1887 caused further displacement. The massacre and subsequent unrest also fed into broader regional conflict, including George Crook's Tonto Basin Campaign of 1872–1873, that continued until 1875.