Background
Even though the first western contact with the Apache of the American southwest was friendly (Francisco de Coronado, 1540—he called them "Querechos"), by the late 16th century, they had gained their reputation through raids on the Spanish settlements and other tribes (it's thought they are partly responsible for "checking" the northern expansion of Spain and Mexico). In defense, the Spanish built a chain of forts (" presidios") throughout the area. This did not dissuade the Indians, who continued, making small and fast raids, then disappearing into the desert before the military could react in force.
Even with Mexican independence from Spain, the raids continued ( horses and cattle being prime targets). In 1848, the Mexican-American War ended with the Treaty of Guadalupe Hildago, in which the United States paid 15 million dollars for territory encompassing parts of (present day) Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming (Mexico also agreed to recognize the annexation of Texas). This began to bring settlement, soldiers, and others passing through—especially due to the discovery of gold in California that year.
While the United States "held the deed" to the land, the Apache point of view was that since they had never been defeated or conquered by the Mexicans (same with the Spanish), it was still their land—the Americans having no valid claim, were considered tresspassers, if not invaders of a sort. The 1850s saw the raids concentrating on northern Mexican settlements but as the years went on and the US presence increased, confrontations between the two became more common. That led to active campaigns to "subdue" the Indians, placing the remainder on reservations (which generally had land unfit for most agriculture or livestock, insufficient supplies, overcrowding—which often led to disease, and were poorly managed by the "overseers," leading to many "breaking" from the reservations and the perpetuation of the raiding).
Eskiminzin and Lt. Whitman
As with most groups, not all Apache can be painted with the same "aggressive," "warlike," or "fierce" (or, in the words of General George Crook: "tigers of the human species") brushstrokes. Eskiminzin was the leader of a group of about 150 Aravaipa Apache (one of the western bands). He wanted peace for his people and safety from the pursuit of "bluecoats" who (as is usually the case in the course of Indian relations) didn't differentiate between different groups and Indians and attacked just because they were Apache.
All Eskiminzin wished for, as terms of peace, was to live on their own lands where they could grow food ("mescal"—not the alcoholic drink, but the roasted leaves of the agave plant that was a staple of the diet for many Apaches). Having heard that the leader of Camp Grant (a small post where Aravaipa Creek met the San Pedro), Lieutenant Royal E. Whitman, was a fair and kind man, he approached the post in February 1871.
He explained his feelings and requested not to be sent to the reservation, stating "let us go to the Aravaipa and make a final peace and never break it." Whitman had no authority to make peace with the band, but genuinely desired to help. He asked that they surrender the their firearms and then they would be allowed to stay near the post until he could discuss the matter with superiors (in this way they would be considered technical prisoners of war, though they were not treated as such in practice).
The Apaches set up a camp a few miles away, planting corn (maize) and making mescal. Whitman was impressed by their hard work and began employing some of them—mostly for cutting hay to feed the cavalry horses—and paying them money, with which they bought supplies. Even some nearby ranchers hired some as laborers. The situation, being both peaceful and mutually beneficial, encouraged other Apaches to join the village (more than one hundred, some from other bands). Meanwhile, Whitman had sent an inquiry to his superiors (which was later returned for "resubmission on proper government forms"). It was April and he was concerned because the Indians were under his watch and he was responsible for their behavior (which had not been a problem) and protection.
The Tucson expedition
That year, other Apache raids had taken place in the general area of Tucson (a true "frontier" town made up of " gamblers, saloon-keepers, traders, freighters, miners, and a few contractors who had made fortunes during the Civil War and hopeful of continuing profits with an Indian war" which was over fifty miles away from Camp Grant). People were terrorized and some killed, livestock and horses taken. The citizenry were outraged and formed a "Committee on Public Safety" for protection.
Interestingly, none of the "incidents" took place at or just outside of Tucson, only in neighboring communities, often miles away. But it didn't stop the "group" from readying itself and chasing off after the offending parties. The people of Tucson decided that the raiding Apaches were coming from the Camp Grant encampment (this, despite the distance they would have to travel and the apparent lack of any evidence to support it)—Indians who were under the protection of the military, making things worse. It wasn't helped by the local newspaper that printed an editorial asking "Will the Department Commander permit the murderers to be fed by supplies purchased with the people's money?" (curious that it was also put into economic terms as well as "safety").
More raids took place. In one instance the Committee chased the party for some fifty miles, caught one Indian and declared him of the Aravaipa band. Another incident occurred—thirty miles away from Camp Grant. The paper and the citizens were further outraged and determined to take care of the problem. An expedition was organized. It consisted of six Americans, forty-two Mexicans, and ninety-two Papago (Tohono O'odham) Indians. The Indians had, partly for their own protection and partly for diplomatic reasons, allied themselves with other tribes and Americans against the Apache. (It is also interesting to note that they were largely "Christianized" as a result of early, amicable relations with the Spanish—something one wonders about given the actions taken later on...though I suppose no more so than that of the "Christianized" whites who organized and went along.)
The Massacre
The expedition arrived in the early hours of the morning before the sun came up (around 4:30). The camp was asleep. The public safety-minded group set up along the bluffs and along the creek. Then proceeded to open fire on the sleeping village. Any who tried to escape were shot at (a number did manage to get away, including Eskiminzin). In a matter of perhaps thirty minutes, nearly all the inhabitants had been slaughtered (as many as 150). Twenty-seven to twenty-nine of the children (the only captives) were taken away and sold as slaves in Mexico by the Papagos. As is sadly typical of many massacres (the Sand Creek Massacre being an extreme, but not isolated, example), the depredations were not relegated to just the murders (see below).
About 7:30, a mounted messenger brought news to Whitman that there was a large party of armed men on the way to the Apache camp (neither had any way of knowing how tragically late the news had come). Whitman immediately dispatched two men who could interpret the warning to the Aravaipa people. They were to be told to pack up and quickly move to the post for protection. The men returned within an hour to report they could find no living Indians (one woman managed to survive).
Whitman and others rushed to the scene. They were greeted not only by death, but fire and mutilation. Whitman:
I found quite a few women shot while asleep beside the bundles of hay which they had collected to bring in that morning. The wounded who were unable to get away had their brains beaten out with clubs or stones, while some were shot full of arrows after having been mortally wounded by gunshot. The bodies were all stripped.
Surgeon C. B. Briesly:
[Two of the women] were lying in such a position, and from the appearance of their genital organs and of their wounds, there can be no doubt that they were first ravished and then shot dead....One infant of some ten months was shot twice and one leg hacked nearly off.
Hoping to communicate his sadness and regret and to let the Indians know it was not his fault and concerned for those survivors who had escaped to the hills, Whitman began burying the bodies. During that, some Apache did return (briefly) to express grief that, in Whitman's words, was "too wild and terrible to be described." His count gave the dead as "an old man and a well-grown boy—all the rest women and children."
Aftermath
Whitman pledged to the survivors that he would see to it that justice was served. Feeling he was to be trusted, many returned and rebuilt the village. And true (nearly) to his word, he finally managed to bring 104 members of the expedition to trial (with the help of President Ulysses S. Grant, who called the incident "purely murder"). It was claimed that they had "followed the trail of murdering Apaches straight to Aravaipa village." Countering that was post guide Oscar Hutton who testified that "I give it as my deliberate judgment that no raiding party was ever made up of Indians at this post." Giving supporting testimony were the post trader, the beef contractor, and the man who carried the mail between the Camp and Tucson.
The trial lasted for five days. Deliberation lasted nineteen minutes. No one was found guilty.
Whitman was personally and professionally damaged. He was, of course, the person who not only defended the "bloodthirsty marauding" Apache, but he tried to have the (let's use the correct terminology) vigilante-murderers convicted for their "civic-minded" actions. After being denied promotions and escaping three court-martials, Whitman resigned.
A few years after the massacre, the Indians were forced to move from their village when the army moved Camp Grant sixty miles away. It was also an excuse to place them on a reservation. After that had made an attempt to (once again) start over as peaceful farmers, but there was an uprising in which an officer was killed. Despite having nothing to do with it, the Aravaipa were blamed and Eskiminzin was chained and jailed (for what was termed a "military precaution"). He and his people escaped, and after four months of cold and starvation, had no choice but to return. Once again, their leader and his subchiefs were confined and chained together: again, a "military precaution." He was released the next summer and allowed to return to his people (though never to the peaceful, undisturbed life he had hoped).
(Sources: Dee Brown Bury My Heart at Wounded Knee: an Indian history of the American West 1970, quotes taken from there; Carl Waldman Biographical Dictionary of American Indian History to 1900 rev. ed. 2001; Atlas of the North American Indian rev. ed. 2000; Encyclopedia of Native American Tribes rev. ed. 1999; www.desertusa.com/mag98/april/stories/campgrant1.html)