Coined by Rolling Stone magazine as “rock and roll’s all-time worst day—a day when everything went perfectly wrong,” the 1969 festival at Altamont Speedway in Northern California was a concert unlike any other. While the free event provided a chance to jam out with The Rolling Stones and some of their famous counterparts, it also gave the fans one hell of a ride. Best known for its shocking violence, destruction, and chaos, Altamont was the angry, intoxicated ruffian who stole the innocence from the summer of love.

It was supposed to be an excellent day of music and good vibes. Mick Jagger from The Rolling Stones was itching to throw a memorable show for his fans, but his manager was having trouble finding a location that would accept the scene. Altamont seemed like the perfect solution—what could be better than a concert out in the middle of nowhere? And for a bit, it seemed he was right. On the night before the concert, approximately 5,000 fans showed up to meet friends, hang by the campfire, share dope, and get psyched. Some people slept and partied in the random wrecked cars left behind from the raceway’s destruction derbies. A hired crew quickly erected the small stage and then everyone just waited for the sunrise…but no one suspected what was headed their way.

Rather than a well-planned public event, Altamont was a blueprint for disaster. With a mere four days notice, it offered a chance to see The Rolling Stones for free, one of the most popular bands of that era. The grounds for the event were chosen precisely because of their barren, treeless, and desolate location, and absolutely no warning was given to anyone living in the nearby area, including the police department. There were very few bathrooms provided and no real set up for the concert itself, just a little wooden stage in the middle of nowhere, standing maybe three feet off the ground.

Once the band started playing, they were literally surrounded on all sides by a sea of people. Lights and sound were given little attention to make the concert more “intimate,” and there was no water, food, or seating offered. And if the crowd got a little too crazy or the band felt threatened in some way? That’s easy—just hire the Hells Angels motorcycle gang to serve as security guards.

Considering it wasn’t just The Rolling Stones playing, but several other well-known bands like The Grateful Dead, Santana, and Jefferson Airplane, planners predicted around 100,000 people to show up for the free show. By 7:30 a.m. Saturday morning, however, the hills were solidly packed with people, and it was clear there had been a miscalculation. As far as the eye could see in any direction, an army of hyped up hippies could be seen advancing over the hills, through the valley, and along the road and railroad tracks, all converging on Altamont. Because the signage outside the venue was nonexistent, people became confused and just left their vehicles, sometimes hiking up to five miles through brush and stickers to find the concert. In the end, the show attracted over 300,000 people looking for one hell of a good time.

Enter the Hell’s Angels, Altamont’s “security” detail. The roar of a hundred motorcycles could be heard for several minutes before the Angels appeared on the crest of the hill and proceeded to head down into the crowd. They did not stop to chat but just drove straight through the thick mass of people, headed for the stage. Most people moved out of the way or even shouted a welcome, but the Angels were not there to be social. Bikes parked and territory secured, a couple of Angels could be seen drinking from a gallon of Red Mountain Vin Rose wine, bragging about the two tabs of mescaline they put in earlier. The Angels had been busy that morning in Berkeley, allegedly buying up thousands of tabs of sunshine acid, a variety known for being particularly speedy. Once their motors were running, drugs could be seen scattered across the stage as the Angels chugged wine and downed reds and speed. The more they partied, the more violent they became, and fighting began to break out at regular intervals.

As soon as everyone settled in and Santana began their set, things quickly turned ugly. As a young man tried to move past a few Angels to get closer to the stage, he was kicked in the face and pulverized with punches that left him motionless on the ground. In another instance, the Angels could be seen beating on a couple of naked fans, and when a photographer tried to capture the scene, they smashed his camera in his face and beat him senseless with sawed-off pool cues resembling billy clubs. As the scene grew hotter, people were ripped off the stage and hammered by several Angels at once. Reports of the spreading violence at Altamont soon made it back to the Huntington Hotel, where the Stones were getting ready to leave for the venue. They were nervous and considered canceling, but at the end of the day, the show had to go on. As their helicopter landed amidst a seething crowd miles deep, regret began to creep back in, especially when Mick Jagger exited the helicopter and was immediately punched in the face by a whacked-out fan.

The Grateful Dead were another highly anticipated show of the evening and were expected to play right before The Rolling Stones and then immediately after. Seeing how the situation was rapidly degenerating, the Dead refused to perform and left the venue, leaving the crowd even more restless and angry than they already were.

Because Mick Jagger wanted the dramatic effect of darkness when he took the stage, The Stones waited another hour or so before making their entrance. There are conflicting reports of what actually went down that fateful evening as The Rolling Stones burst into their first song of the night, “Sympathy For The Devil.” A young black concertgoer by the name of Meredith Hunter was nearing the front, and obviously very high on something, he attempted to jump up and join some of the other fans dancing on the stage. At that point, it is known he was violently pushed back by several Angels and, irritated by this treatment, shoved them back. The Angels claim he then brandished a gun at them, giving them no choice but to stab him to death. Other eyewitness accounts tell a much more horrific story of how one Angel, in particular, chased the young man through the crowd, stabbing him the back as he ran. Hunter then took out the gun in a moment of desperation to save his own life and the Angel slapped it away, stabbing Hunter in the side of the head and then kicking him over and over in the face until there was no face left.

Two witnesses to the brutalization of Hunter approached him once the Angel had left and tried to help him to safety. As they carried his bloody body through the chaotic crowd, trying to scream to the band to stop the music, they realized it was futile.

The crowd would not let them through and The Rolling Stones could not seem to hear or see them clearly, although they did shield their eyes a few times in an effort to see out into the darkness, sensing something bad was happening. Eventually, the two men carried Hunter’s body around the side of the stage and delivered him to the Red Cross tent. He died soon thereafter.

Up until then, all the hateful energy from the Angels had been focused on the troublemakers. Several stretchers were passed back through the crowd to remove those who could not longer stand, and as The Rolling Stones launched into “Under My Thumb,” a body sailed across the stage. Although Jagger had made some feeble protests up until this point, he apparently became increasingly upset and threatened to stop playing if the Angels didn’t cool off. It was a menacing moment as he stopped the music to calm down the crowd, but the Angels did nothing to help him. They’d been watching his flamboyant performance with amusement and shared disdain. They could take this guy, so who does he think he is? The Angels parked in the front of the stage gunned their engines defiantly, and then it all became perfectly clear. The musicians might be the ones playing the music, but they were most certainly not the ones in charge.

Someone had to answer for the stabbing of young Meredith Hunter. The Angel who had murdered him with thousands of witnesses was the obvious choice, and so a trial began one year after Altamont.

Despite the damning evidence and testimony, Hell’s Angel Alan Passaro walked on all charges. Most people, including the all-white jury, didn’t know much about Altamont except there had been a dustup there with some young people around Christmastime the previous year. When it came to determining guilt, perhaps it was just easier to assume a black man (and certified speed user) was the one to blame for the incident. To this day, the Hunter family has never received justice for the death of their son or an apology from The Rolling Stones, who apparently put together one of the most careless and lethal concerts in history.

And the rest is history.