By Owen Gleiberman
Updated December 06, 2009 at 06:04 PM EST

Forty years ago today, the 1960s came to an unholy end. As evening approached on Dec. 6, 1969, the Rolling Stones, who were then just reaching the height of their street-fighting Satanic majesty, took the stage at Altamont, a hastily organized, all-day-long free rock concert held on the outskirts of San Francisco — an event planned, in essence, to be a kind of Woodstock west. Infamously, though, this was no happy-mud orgy of peace, love, and good vibes. The very fact that the concert was held next to a gritty speedway was a sure sign that no one there was really planning to get “back to the garden.” From the start, the crowd was testy and anxious and very drugged up, marked not by that moony-eyed, almost bovine Woodstock benevolence but by a certain West Coast aggressive good-time solipsism. Over the course of the day, scuffles broke out, most of them prompted, in one way or another, by the Hell’s Angels, who had been hired, for $500 worth of beer, to patrol the front of the stage, which they did using sawed-off pool cues as weapons.

Shockingly, the stage was only four feet high, with nothing but a few yards of grass in between the audience and the performers. I’m not sure if a Miley Cyrus concert would come off without a bare-knuckle fight or two under those conditions. As the day wore on, the unruly incidents escalated, and by the time the Stones took the stage, the whole event was a pressure cooker looking for release. Just after the band finished playing “Under My Thumb,” Meredith Hunter, a young black man in a lime-green suit, high on methamphetamine and brandishing a gun, was stabbed in the back, five times, by one of the Hell’s Angels; he died shortly afterwards. This sickening event was immortalized when it was caught on film by David and Albert Maysles, who featured it in Gimme Shelter (1970) as the horrific snuff climax of the ’60s.

Here’s what I wrote in EW about this cinéma vérité classic when it was re-released in 2000:

Gimme Shelter…remains the only rock & roll film that exerts the saturnine intensity of a thriller. It’s like Woodstock directed by Oliver Stone. As the movie spirals toward its bloody catharsis, it feels like nothing so much as a rite of exorcism, with the queasy yet inexorable pull of multiple dark forces coming together. The Hell’s Angels, it’s clear, were looking for a fight (in an era that hated the cops, they got to be the cops), and the concert was atrociously planned…Yet none of this might have mattered much if the hippies, roughnecks, and love generation waifs weren’t already imploding under the anarchic spell of their own freedom. What they needed shelter from, it turns out, was themselves.”

Thinking back on Altamont, it’s easy to get moralistic, to view the concert as a lesson that the counterculture needed to teach itself. The hippies were trying to create a life without rules, based on the idea that if you let people be “free,” they’ll be good to one another. That, of course, was a notion profound in its naiveté. So Altamont was, in a sense, a kind of comeuppance to the arrogance of youth. The first half of Gimme Shelter features the Stones on stage at Madison Square Garden, in the middle of their 1969 tour, and it’s still amazing to behold the cock-of-the-walk Sybaritic grandeur of Mick Jagger in his prime, as he flounces and gyrates and struts around in an American-flag top hat. Later, on stage at Altamont, launching into “Sympathy for the Devil,” he is put in the paradoxical position of being chastened, if not downright intimidated, by the anarchy unleashed by his do-what-you-feel charisma.

Like most people, I’ve always thought of Altamont in terms of what ended that day. The counterculture would, in many ways, go on — for a lot of folks, it was just getting started. There was more indulgence in “sex, drugs, and rock & roll” in the first half of the ’70s than there ever was in the ’60s. What crashed and burned at Altamont (with more than a bit of a deathly jump start a few months earlier by the Manson murders) was, of course, the idealism, the utopian reverie of the ’60s: the vision of a harmonic rainbow society that could overturn the established order. That dream died because, in hindsight, it was always a starry-eyed boomer fantasy.

Yet watching Gimme Shelter again just a few days ago, what struck me most about Altamont is that it also marked, in its way, the beginning of something. As the Rolling Stones perform, the area in front of the stage becomes, in effect, the world’s first mosh pit. Our eye keeps getting drawn to the crowd as it surges and buckles. Mick Jagger is doing the same moves that were so mesmerizing in the Garden concert, only now, in a strange way, he’s upstaged by the power of the audience. They take over the concert; they take over the movie. And suddenly, the Rolling Stones are mere bit players in their own rock & roll seance. What you see in Gimme Shelter, apart from the end of the hippie dream, is the dawn of a new age, the one that we’re in right now, with the audience surging forward to become a drama unto themselves, maybe even threatening to take the place of the artists they once revered.