The army that fucks together, fights together. At least that was the unofficial motto of the Weathermen’s Smash Monogamy program of 1969. After an afternoon of bombing government buildings, members of the notorious radical leftist group would then go home, drop acid, party, and have sex.

But these orgies weren’t just to boost morale. They were designed to emphasize collectivism, while deprioritizing individual identities.

The Weathermen organization—later known as the Weather Underground—was founded on the University of Michigan campus as a faction of Students for a Democratic Society (SDS). Leaders chose the name from a Bob Dylan lyric, “You don’t need a weatherman to know which way the wind blows.”

Aiming their revolution at the rich and powerful, members used violent tactics in an attempt to overthrow the US government, specifically to end racism and imperialism and create a classless, communist society.

In October 1969, a Weathermen group of about 200 stormed affluent Chicago neighborhoods, throwing bricks through windows and rushing police brigades. Sixty-eight Weathermen and women were arrested.

The event marked the beginning of a period the Weather Underground dubbed “The Days of Rage,” a series of direct actions intended to create chaos and wake affluent people to urgent issues like the Vietnam War and racial tensions. It was also a recruitment period: the organization charged through and wreaked havoc in an attempt to rally angry youth.

But as the organization’s membership grew, leaders subjected recruits to intense initiation rituals. In Days of Rage: America’s Radical Underground, the FBI, and the Forgotten Age of Revolutionary Violence, Bryan Burrough writes of all-night interrogations in which people would be hazed, verbally assaulted until they broke. If they didn’t, they could stay on as “obedient, unquestioning soldiers.”

In Detroit, the Weather Underground commanded every member to break up with his or her romantic partner. Eventually known as Smash Monogamy, the program scheduled mass orgies with the intent of making the relationship with the group the only one that mattered.

After an orgy in Columbus, Ohio, member Gerry Long recalled:

“Within minutes, there was a whole group of naked people looking down from the head of the stairs, saying, “Come on up!” I took the hand of this girl and exchanged a few pleasantries to give it a slightly personal quality, and then we fucked. And there were people fucking and thrashing around all over. They’d sort of roll over on you, and sometimes you found yourself spread over more than one person. The room was like some modern sculpture. There’d be all these humps in a row. You’d see a knee and then buttocks and then three knees and four buttocks. They were all moving up and down, rolling around.”

Along with drugs, the Weathermen encouraged sexual experimentation with both genders. Leader Bill Ayers called his group an “army of lovers,” and himself had sex with his best male friend.

But after several months, the orgies were stopped. Weatherman Mark Rudd claimed they complicated the group’s mission with jealous distractions. In truth, the rampant spread of STDs was the nail in the coffin. Dozens of people suffered from gonorrhea, pelvic inflammatory disease, and crabs. They called it the “Weather crud.”

In the meantime, the Days of Rage continued. Though many members were arrested and bail tallied in the millions, the Weather Underground had rendered enough damage to get noticed. They were “the ‘heavy edge’ of the New Left, the furthest left, the wildest, the craziest, the most committed,” writes Burrough.

Eventually, they graduated from hurling rocks and bottles at police. Weather members went underground and planned a full guerilla war, “leading white kids into armed revolution,” said leader Bernardine Dohrn. On March 6, 1970, however, a Weather bomb detonated prematurely in a Greenwich Village home. Three members were killed.

Outside the Greenwich Village “bomb factory” where three Weather Underground member were accidentally killed in 1970. (AP Photo/Jerry Mosey) Still, in June 1970 members bombed a New York City police department. In October, Dohrn was added to the FBI’s 10 most wanted list. On March 1, 1971, they bombed the US Capitol Building. On May 19, 1972, Ho Chi Minh’s birthday, a bomb erupted in a women’s bathroom at the Pentagon. The Weather Underground claimed responsibility, saying the event was “in retaliation for the U.S. bombing raid in Hanoi.”

Before their bombings, the Underground would release communiqués warning of the location. While no one was killed, revolutionary violence was crucial, they argued.

By 1975, the New Left had disintegrated and the Weather Underground shut down. But even decades later, Bill Ayers, dubbed one of the group’s “rich kid radicals” was largely unapologetic. Interviewed for a New York Times piece that published on September 11, 2001, he said, “I don’t regret setting bombs. I feel we didn’t do enough.”