In May of 1919, Greek soldiers occupied the Ottoman province of Smyrna, in what is modern day Turkey. During the initial invasion, they massacred somewhere between dozens and hundreds of civilians. The exact number was lost in the chaos of war.

A Turkish teenager, Muzafer Sherif, witnessed many killed that day, and nearly became a casualty himself. Standing by as a Turk was run through by a Greek bayonet, Muzafer thought for certain that he would be next. The soldier readied his weapon and looked at the boy, but then turned and walked away.

It was one more bloody day between these two lands in a sequence as long as recorded history, going back to when Alexander the Great quarreled with the Persians. Muzafer likely would have known this history, but on that particular day the reality of human conflict jumped out of books to burn itself vividly into his mind. In one of the few times that he ever discussed those years, Muzafer wrote that he had seen great compassion and self-sacrifice within human groups, matched only by their hatred and “bestial destructiveness” toward outsiders. It became his life’s work to understand why.

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Fast forward to 1954, when two dozen Oklahoma City public schools received visitors wielding credentials from “higher educational authorities.” The guests asked to observe the 5th graders at recess and examine their school records. They were looking for “normal” boys—white, Protestant, middle class, with similar IQ scores, no physical abnormalities or problems in school, and living in two-parent families. Boys from foster care or “broken homes”—divorces were still a relative anomaly—were absolutely excluded.

Selected boys were offered the chance to go to a three-week summer camp at Robbers Cave State Park. A man whom the boys would know only as the “camp director” met with their families. He collected a $25 nominal fee for tuition and made the parents promise not to visit, saying it would contribute to homesickness. To further ensure seclusion, “Restricted” and “No Trespassing” signs were posted around the 200-acre campgrounds.

The camp was planned by a husband-and-wife team from the University of Oklahoma, well-known experts in social psychology: Muzafer and Carolyn Sherif. It would be the third boys’ camp arranged by the Sherifs to study group dynamics. Two others had previously been held in Connecticut. In the earlier camps, the psychologists had watched in-groups of boys spontaneously emerge and begin to develop tensions with outsiders. With this camp, they would go much further.

The psychologists’ research into social groups revolved around goals. They believed that “in-groups” naturally emerge when people must work together to solve a common problem. As part of this process, a group will develop its own culture and hierarchy. If the “in-group” then finds itself in competition with an “out-group,” tensions and stereotypes will develop. These tensions are “functional” because they motivate a group to defeat the others and achieve its goal. But once stereotypes become part of the shared cultural beliefs of a group, they may persist beyond the point when they served any useful function. It is then only by a shared goal requiring cooperation between groups that they consider reconciliation.

Muzafer’s life had been only slightly less eventful since he escaped World War I. He had earned degrees from Harvard and Columbia, and before World War II he returned to Turkey—to teach psychology at Ankara University. Turkey stayed neutral during the Second World War, but some officials held sympathies for Nazi Germany. Muzafer wrote several books and helped publish a periodical with anti-Nazi messages, and in 1944 he was jailed for “actions inimical to the national interest.” The prosecutor sought a 27-year sentence, but thanks to pressure from some of his Harvard schoolmates (now high-ranking State Department officials), as well as the increasing likelihood that Germany would lose the war, Muzafer was released after 40 days in solitary confinement. He had spent his prison time developing the outline for a social psychology textbook.

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In 1949, Muzafer came to the University of Oklahoma with Carolyn Wood Sherif, his wife and close collaborator. Carolyn wrote of their introduction, “I had decided that I wanted to marry an intellectual, as well as sexual and emotional partner, who would encourage my being a social psychologist. The idea was based on literature I had read, not realities I saw, and it was romantic in the extreme. The impact of meeting Muzafer Sherif, already a well-known contributor who espoused social psychology and male-female equality with equal fervor, and whose work had already inspired me, cannot be overdrawn. He asked me how far I wanted to go in social psychology, and I replied, ‘All the way.’ ”

By all accounts, theirs was an equal partnership, though Carolyn would be frustrated much of her life when her contributions were not acknowledged in the larger academic world. As she put it, “a careful historian will recognize that both of us were involved in everything published under the name of Sherif after 1945.” A new research institute was created at OU for Muzafer, who served as director. Though the Sherifs worked side by side there for 17 years, Carolyn was never given a regular faculty appointment.

Muzafer’s passion for his work was great enough that his research assistants were terrified of letting him drive. He would engage in emphatic discussions about social psychology while behind the wheel, often at the expense of safety. As colleague O.J. Harvey recalled, Muzafer “would first hint, intensify the hint, and then insist on being allowed to drive.” Once in the driver’s seat, he might go “from 10 miles per hour to 90, and on either side of the road, with both arms waving if he was making some big point.”

With grant funding from the Rockefeller Foundation, the Sherifs had reserved an isolated Boy Scout campground. The building of these campgrounds was described in a 1931 edition of The Daily Oklahoman, under the headline, “A Kingdom for Boys.” The labor of fifteen inmates was donated by the warden of the state penitentiary at McAlester. They spent months constructing water lines, camp houses, kitchens, and other buildings. As the Oklahoman described it, “Four white men and 11 Negroes make up the construction gang. They have their own tent camp with fireplaces of their own making. They do their own cooking, washing and maintain themselves as a separate construction company. They have not been under supervision of even a guard from the penitentiary.” This “Tom Hale Camp”—named for the president of the Choctaw council who donated $1,000 for its development—is still used by the Boy Scouts today.

It was an ideal location for the Sherifs’ research. They could study small groups in situations that were carefully manipulated, yet more realistic than a psychology lab. The eleven and twelve-year-old boys picked for the camp were carefully selected to have similar race, religion, class, and family backgrounds, so there would be no major reasons for conflict besides those introduced by the experimenters. They brought only one boy from each school so that none would know any of the others beforehand. With a homogenous group of young boys in an isolated environment, they hoped to exclude the variables of race, class, and history to uncover a more pure example of human conflict. The psychologists went to great lengths to keep the boys from knowing they were in an experiment. (Research ethics were less strict at the time.) The Sherifs and their assistants posed as ordinary camp staff, and they took down notes only when the children were not present. Hidden tape recorders were scattered throughout the campgrounds, and when the kids first arrived, staff members acted like shutter bugs, conspicuously taking pictures of everything they saw, so this would not attract attention later. Muzafer himself played the role of the camp janitor.

Groups of eleven boys each were set up on opposite sides of the campground. For the first week of camp, the groups remained isolated and unaware of the other’s presence. Because the experimenters wanted groups to emerge with as little interference as possible, the boys were given free rein to explore and form a society in miniature: they scouted hideouts, built diving boards and rope bridges at nearby swimming holes, had run-ins with rattlesnakes and copperheads.

* * *

Leaders emerged. In Group 1, a boy called Mills often made himself the center of attention by clowning (all of the names are fictional, given to the boys by the researchers). In one incident, he started a pine cone fight that ended with him in a tree being pelted by all of the others. “Where’s my fellow men?” Mills shouted, and a boy replied, “Look at our leader!”

In honor of several rattlesnake encounters, the boys dubbed themselves the “Tom Hale Rattlers.” Mills created a stencil to decorate group t-shirts, hats, and a flag. On the third day, Mills hurt his toe but did not reveal it until bedtime. From then on, it was established that the Rattlers were “tough” and did not complain. As part of this “tough” persona, cursing grew rampant.

In the second group, a boy called Craig took charge at first. He introduced a song on the bus ride to camp that was soon called “our song.” Another popular boy was Mason, who stood out as the most capable baseball player. A boy swam without trunks one day and was called “Nudie,” but after Mason took it up, the rest followed suit.

A couple of boys in Group 2, Boyd and Davis, struggled with homesickness. Boyd would frequently break into tears. Davis would try to comfort him, only to end up crying himself. The researchers decided they could not help the boys without distorting the experiment, so Boyd and Davis were sent home.

The rest of the group rallied. After discovering they were gone, Craig said, “Things are going to be better around here now.” Another boy, Wilson, gibed, “They chickened out.” Mason, who had himself struggled with homesickness, replied, “They are the only boys who will.”

After the boys naturally coalesced into tribes, the experiment moved on to stage 2. The Sherifs introduced rivals. Near the end of week one, they arranged for the two groups to be within earshot for the first time. The reaction was immediately negative. Without seeing the other group, Wilson referred to “those nigger campers.”

After learning of the Rattlers’ existence, Group 2 decided it also needed a name. One boy suggested Rattlesnake Biters, but they settled on the Eagles.

The Sherifs then ramped up the conflict. Counselors told the boys there would be a series of contests: baseball, touch football, tug of war, tent pitching, skits and music, cabin inspections, and, as the grand finale, a treasure hunt—the more subjective events were included so the researchers could pick winners that kept the competition close if one team proved much better at athletics. Each boy on the winning team would get a four-bladed pocket knife, among other prizes. Throughout the tournament, the running score was displayed in the mess hall in the form of rising thermometers.

The contests began with baseball, a pastime the boys took very seriously. The Rattlers arrived at the field first, and then the Eagles approached, singing the notes of the “Dragnet” theme (“Dun da-dun dun … dun da-dun dun daaaa!”) and carrying a flag with the motto: “You may win but we will give you a hell of a fight.”

Despite the Eagles’ bravado, the Rattlers took an early lead, winning the first baseball game and tug-of-war. After their defeats, the frustrated Eagles noticed the Rattlers’ flag had been left on the diamond backstop. They rushed to the flag and tore it down. “Let’s burn it,” someone suggested. Another boy found matches. They hung the scorched remains back up for the Rattlers to find, a few letters and a picture of a snake still visible.

* * *

As the research report put it, in the restrained language of academic psychology, “This flag-burning episode started a chain of events which made it unnecessary for the experimenters to introduce special situations of mutual frustration for the two groups.”

The Rattlers discovered their desecrated flag the next morning. The boys clustered around, shouting excitedly. Simpson, the baseball captain, came up with a plan. When the Eagles arrived, he would demand an accounting. When the Eagles confessed (no one doubted they would), he would throw the first punch, and the others would back him up. A boy called Martin volunteered to grab the Eagle flag and burn it.

It went as planned. Martin took off with the Eagle flag, with several Eagles and Rattlers in pursuit. Remaining Eagles grabbed another Rattler flag and tore it apart. Rattler Swift put Craig in a wrestling hold, demanding, “Which one of you guys burned our flag?” Craig shouted back: “We all did!”

Fistfights broke out, and the staff intervened to stop it. Then Mason returned, after witnessing the Rattlers burn the Eagle flag. He was “crying mad” and yelling for someone “my size” to fight. “Here I am!” responded Mills. The staff had to pull them apart again.

Eventually the groups settled down enough to play another game of baseball, with plenty of jeering on both sides. Among the epithets thrown between teams: “stinkers,” “cheats,” “damn niggers,” “communists,” “fatty,” “tubby,” and “Little Black Sambo.”

This time, the Eagles won. Mason said the victory was due to their prayers, and another boy suggested the Rattlers lost because they cuss so much. “Hey you guys!” he shouted over everyone. “Let’s not do any more cussing, and I’m serious, too.”

Things escalated that night. The Eagles took the second tug-of-war match, and the increasingly frustrated Rattlers planned a raid. They covered their faces and arms with warpaint. At 10:30 p.m., they charged into the rival cabin. The Eagles, torn from their sleep, sat stunned as the Rattlers flipped over beds and ripped down mosquito nets.

When they recovered from the shock, the Eagles were ready to retaliate, but the researchers posing as camp staff stepped in “when it was mentioned that rocks would be used.” Celebrations ensued back at the Rattlers’ cabin. Mills had stolen comic books and a pair of Mason’s blue jeans. He painted “The Last of the Eagles” in orange down each leg and carried them like a flag.

The retaliatory raid came the next morning. After making sure the Rattlers were at the mess hall, the Eagles broke into their cabin armed with sticks and bats. They trashed the place and returned to their own cabin, where they prepared socks filled with rocks in case the Rattlers returned.

* * *

Tensions had risen alongside the now red-hot thermometers that kept the scores. With some help from the researchers, the Rattlers and Eagles stayed close to the very end. On the last day, counselors gathered both groups together with the prizes between them. They announced the results for each contest one by one. It came down to the final event: the treasure hunt. Staff read out the times. Rattlers: 10 minutes, 15 seconds. Eagles: 8 minutes, 38 seconds.

The Eagles had won. (The boys didn’t know that the experimenters had made sure of it by giving the Eagles an easier route.) The winners hugged, shouted, and jumped in the air. Mason broke into happy tears. The losers sat silently on the ground.

It didn’t take long for the Rattlers to have their revenge. When the Eagles left to swim in a nearby creek, the Rattlers again raided their cabin. They ransacked the room, untied boats from the dock, and stole the prize knives and medals.

When the Eagles discovered what had happened, several boys rushed to the Rattler cabin. The groups lined up across from each other, shouting over an invisible line. The Rattlers said they would return the knives and medals if the Eagles got down on their bellies and crawled. Mason again demanded someone his size to fight, but the Rattlers refused to take out their two biggest boys. When fights did break out among some of the others, the experimenters decided to intervene to avoid serious injuries.

Just two weeks into camp, and a mere week since the groups first engaged, the Sherifs had expertly created a situation that turned young boys into bitter enemies. In the last week, they would try to make them friends.

Conciliation came slowly. With any contact, the boys would yell slurs and hold their noses. They complained about eating in the same mess hall, and multiple meals descended into food and garbage fights. When contact by itself did not reduce tensions, the experiment moved to the next stage: introduce problems that would require group cooperation to resolve, what the researchers called “superordinate goals.” So they turned off the water.

The experimenters disabled a valve going to the camp’s water main and covered it with boulders. They stuffed sacking into the faucet at the water tower that fed the main. Then staff announced they were having problems with the water system. To cover themselves, they mentioned that vandals had damaged it in the past.

After turning off the water in the morning, the experimenters waited until 4 p.m. The high that day was close to 100 degrees. The boys had almost used up their canteens and were growing parched. A staff member made an announcement.

“Fellows, we haven’t been able to find the trouble yet,” he said. “It may be at the tank; it may be the valves, or in the pump or intake; or it may be a leak in the line. We just don’t know. Now we need your help to find the trouble.”

The boys split up and examined the whole system before finally converging at the tank, partway up a mountain more than a mile from the campsite. It took 45 minutes of work by multiple boys digging out the sacking with their knives to finally access the water.

Tensions remained, but there were signs of a thaw. At breakfast the next day, a few boys exchanged howdys. The experimenters introduced more situations requiring cooperation: they rented a movie with donations from both groups; they revived a “stalled” truck that was needed to retrieve food by pulling it with a rope. Celebrating together, the boys announced they had “won the tug-of-war with the truck.”

For the Sherifs, the experiment was a resounding success. It was not any innate difference between the Rattlers and the Eagles, or the Greeks and Turks, that set them at each other’s throats—just a coincidence of geography. Their results were described in an influential report, “Intergroup Conflict and Cooperation: The Robbers Cave Experiment.” This became the basis for realistic conflict theory, a tool to better understand prejudice and discrimination—how even similar groups could so easily fall into conflict and violence, but also how it might be resolved.

By the end of week three, the efforts had gone so well that the boys chose to ride back to Oklahoma City on the same bus. They took turns singing the favorite songs of both groups. Towards the end of the trip, some boys began to sing “Oklahoma!”, and everyone rushed to the front of the bus to join in.