Yippie demonstrators swarming a statue in Grant Park during the 1968 Democratic National Convention. Julian Wasser/The LIFE Images Collection/Getty Images

In late August of 1968, Americans freshly traumatized by the assassinations of both Martin Luther King, Jr. and Robert F. Kennedy, faced reports about new violence—this time at the Democratic National Convention in Chicago. As the evening news broadcast images of billy club-wielding police beating antiwar protesters in the streets, Americans were forced to reckon with a new political reality, in which the old guard political machine was being challenged by a groundswell of long-haired kids calling for revolution.

At the center of the clashes in Chicago was an emerging group of political pranksters calling themselves the Yippies.

Unlike the serious-minded Students for a Democratic Society (SDS), which organized the biggest anti-war protests and teach-ins at American colleges in the sixties, the Yippies were a loosely held confederacy of anarchists, artists and societal dropouts lead by the theatrical activist Abbie Hoffman and his compatriot Jerry Rubin, a veteran anti-war protester.

By the late 1960s, Hoffman and Rubin had come to believe that American politics and culture had devolved into a state of abject absurdity. The War in Vietnam was absurd. Consumerism and greed were absurd. The political rhetoric coming from both parties was absurd. And the only way to fight serious absurdity, Hoffman and Rubin decided, was with absurdity itself.

During an anti-war march in 1967 in Washington, DC, Hoffman, Rubin and the poet Allen Ginsberg organized a public exorcism of the Pentagon. Dressed in wild costumes and aided by Mayan healers, the crowd attempted to cast out the demons of war and even to levitate the massive five-sided home of the U.S. Department of Defense.

Later that year, Hoffman and company snuck into the New York Stock Exchange and rained hundreds of dollar bills down upon the trading floor. News cameras rolled as the stockbrokers scrambled to pocket as many bills as possible, their greed effectively bringing the stock exchange to a standstill.

"The image was the message."

“The image was the message,” says Jonah Raskin, an emeritus professor of communication studies at Sonoma State University who was friends with Hoffman and wrote the 1992 biography For the Hell of It: The Life and Times of Abbie Hoffman. Raskin describes Hoffman and Rubin’s colorful protest methods as “guerilla theater” tailor-made for TV cameras.

Hoffman and Rubin’s ragtag crew didn’t officially become the Yippies until January 1968 when the group got high in a New York apartment and dreamed up the best way to protest the upcoming convention in Chicago. The Democratic party, in their eyes, had become the “National Death Party” for its staunch support of the Vietnam War.

READ MORE: How Political Conventions Began—And Changed

Yippies parading their presidential candidate, Pigasus the pig, during the 1968 Democratic National Convention. Julian Wasser/The LIFE Images Collection/Getty Images

The Yippies Stage a Counter-Convention

Rubin proposed organizing a counter-convention called the “Festival of Life” to be held in a nearby park. There would be music, marijuana and crowds of beautifully freaky young people laughing down the convention of death. They’d nominate a pig for president, dance through the streets of Chicago and grab media attention from the meaningless spectacle inside the convention center walls.

After hearing the idea, Hoffmann and Rubin’s friend Paul Krassner spontaneously yelled out “Yippie!” and the word instantly stuck. The joy and silliness of “Yippie” encapsulated the spirit of the group’s unique brand of positive political theater. Hoffman’s wife Anita, worried the press wouldn’t take them seriously, came up with a “straight” version, the Youth International Party (YIP).

The whole point of the Festival of Life, as it was first conceived, was to “stick it to the man” through a massive expression of joy.

“A revolution was supposed to be fun,” says Raskin. “It wasn’t supposed to be ‘grit your teeth and suffer through it.’ That wasn’t the idea. The idea was ‘yip, yip, yippie!’”

On January 16, 1968, the Yippies released their first manifesto as an open invitation to occupy Chicago during the convention for an “international festival of youth music and theater.”

“Come all you rebels, youth spirits, rock minstrels, truth seekers, peacock freaks, poets, barricade jumpers, dancers, lovers and artists,” read the manifesto. “It is the last week in August and the NATIONAL DEATH PARTY meets to bless Johnson. We are there! There are 500,000 of us dancing in the streets, throbbing with amplifiers and harmony... celebrating the birth of FREE AMERICA in our own time.”

American political activist Abbott ‘Abbie’ Hoffman speaking to a journalist from the amidst a crowd of demonstrators protesting the Democratic National Convention at Grant Park in Chicago, Illinois, August 28, 1968. Santi Visalli/Getty Images

Tensions Paved the Way to Violent Protests

But a lot changed between January and August. In March, President Lyndon Johnson announced that he would not be running for reelection. Then came the shocking murders of King and RFK, the latter widely considered the frontrunner for winning the Democratic nomination. In Vietnam, the Tet Offensive (January-September 1968) brought high casualties that swayed the majority of Americans against the war for the first time.

And in Chicago, Mayor Richard Daley braced his police force for an August showdown with protestors. Daley fortified the convention hall with barbed wire fence and called in the Illinois National Guard. He made it clear that any outside agitators intent on spoiling his city’s convention would be met with physical force.

Blake Slonecker, a history professor at Heritage University and co-editor of the academic journal The Sixties, says that by late August it was clear that violent clashes between protesters and the police during the convention were almost certain.

“A lot of anti-war protesters hesitated to go or didn’t go because they saw that coming,” says Slonecker. “Students for a Democratic Society, in the months leading up to Chicago, went back and forth on whether to support a protest there.”

The Yippies, for their part, pressed on, although the numbers that descended on Chicago were a small fraction of the 500,000 first imagined. An estimated 10,000 protesters from various groups were in Chicago for the convention. Denied a permit to have a music festival or even to lawfully protest, the Yippies still held a mock convention for their candidate, Pigasus, a 145-pound pig raised by Yippie folk-singer Phil Ochs.

The Yippies were among the throng of protestors and news media in Grant Park on the afternoon of August 28, when police swarmed a young man who tried to lower the American flag. The protestors responded by hurling insults and rocks at the police and National Guard troops, who broke into an all-out riot. Hundreds of unarmed protestors were tear-gassed and indiscriminately beaten, all of it caught on camera.

There’s little doubt that Yippie leaders understood that violent conflict in Chicago was inevitable and even advantageous to their cause.

“What happened was in a lot of ways what the Yippies planned to happen,” says Raskin. “They wanted to unmask the society. The Yippies, by pushing freedom of expression and the First Amendment to the limits engendered a police riot. And people watching at home on their TV sets saw that, when it came down to it, Chicago was a police state.”

(L-R from top) Jerry Rubin, Abbie Hoffman, Tom Hayden, Rennie Davis, Bobby Seale, Lee Weiner, John Froines and David Dellinger, circa 1968. The Chicago Seven, after Seale was severed from the case, were indicted for conspiracy and inciting a riot during the 1968 Democratic National Convention in Chicago, Illinois. Hulton Archive/Getty Images

The Chicago Eight Go to Trial

But the true watershed moment for the Yippies was yet to come. Six months after the convention, Hoffman, Rubin and six other men—from the SDS, Black Panthers and other groups—were arrested and charged with conspiracy to incite a riot, obstructing police officers during a civil disorder and other crimes. Their trial, known as the Chicago Eight (later reduced to the Chicago Seven), became a national media sensation and Hoffman and Rubin made the most of it.

“Jerry and Abbie reached their creative peak at the trial, doing things like going to court in black judicial robes, taking them off and having Chicago police uniforms underneath the robes,” says Raskin.

Hoffman, meanwhile, took full advantage of his court appearance to play up the Yippies’ absurdist approach to protest. When asked by his defense attorney where he resided, Hoffman responded, “I live in Woodstock Nation.” And when asked to tell the court where that was, he said, “It is in the state of mind, in the mind of myself and my brothers and sisters. It is a conspiracy. Presently, the nation is held captive, in the penitentiaries of the institutions of a decaying system.”

Hoffman and Rubin were convicted of conspiracy and sentenced to five years in prison, but the conviction was reversed on appeal. The Yippies never again achieved the notoriety of the convention and conspiracy trial but the spirit of the group lived on among its members.

“The crucial thing about the Yippies is they created this American form of cultural revolution,” says Raskin. “They were lifestyle revolutionaries. It was your hair, how you live every day, what you eat, what you drink, the language that you use. I think that has gone on.”

READ MORE: 7 Reasons Why the Chicago 8 Trial Mattered