On March 8, 1965, two battalions of U.S. Marines landed on beaches of Da Nang, marking the first official engagement of American troops in the Vietnam War. Over the next several years, as the United States escalated its ill-fated involvement in that conflict, hundreds of thousands of Americans joined in mass protests across the country, repulsed and outraged by the terrible bloodshed taking place in Southeast Asia.

Though the anti-war movement had begun on college campuses at the dawn of the 1960s, more and more people joined in opposition to the war in the latter half of the decade, as television brought images of its atrocities into American homes in a new level of excruciating detail.

The hippie counterculture, which emerged in the late 1960s and grew to include hundreds of thousands of young Americans across the country, reached its height during this period of escalation of American involvement in the Vietnam War, and subsided as that conflict drew to a close. But hippies’ rejection of mainstream American culture, and their distinctive brand of rebellion—including their long hair and beards, colorful style, psychedelic drug use, love of rock music and eco-conscious lifestyle—left a lasting impact on the nation in the decades to come.

In many ways, the hippies of the 1960s descended from an earlier American counterculture: the Beat Generation. This group of young bohemians, most famously including Jack Kerouac, Allen Ginsberg and William S. Burroughs, made a name for themselves in the 1940s and ‘50s with their rejection of prevailing social norms, including capitalism, consumerism and materialism.

Centered in bohemian havens like San Francisco and the East Village of New York City, Beats embraced Eastern religions, experimented with drugs and a looser form of sexuality; their followers became known by the diminutive term “beatniks.”

“What’s significant about [the Beats] is that the movement was very small, it was literary—so it had a claustrophobic quality about it,” explains William Rorabaugh, professor of history at the University of Washington and author of American Hippies (2015). “You weren't allowed to be in the group unless you were either a friend of or a poet."

As the 1950s gave way to the 1960s, the Beats and beatniks gradually gave way to a new kind of counterculture: the hippies, who actually preferred to call themselves “freaks” or “love children.” The hippies were much younger than the beatniks (they could even have been the Beats’ children) and had a much different style. They listened to folk and rock music, not jazz; they dressed flamboyantly, in bright colors, where the Beats and beatniks had favored shades of black and grey. Ripped jeans, bell bottoms, tie-dyed clothing and flowers worn in the hair were all big parts of the typical hippie style.

The biggest difference between the hippies and the Beats? “LSD came on the scene,” Rorabaugh says. “The hippie counterculture, more than anything else, was about taking LSD. Seeking spiritual perfection through drugs, but particularly through psychedelic drugs."

The vast majority of hippies were young, white, middle-class men and women who felt alienated from mainstream middle-class society and resented the pressure to conform to the “normal” standards of appearance, employment or lifestyle. By wearing their hair long and growing beards (for the men), taking drugs and exploring spirituality outside of the confines of the Judeo-Christian tradition, hippies sought to find more meaning in life—or at least have a good time.

Though the Haight-Ashbury neighborhood of San Francisco and New York City’s East Village were famous hippie meccas, the movement thrived all over the country.

In a cover story published in July 1967, during the “Summer of Love,” Time magazine reported that the hippie movement was “blooming in every major U.S. city from Boston to Seattle, from Detroit to New Orleans,” encompassing some 300,000 people. Many hippies eventually chose to move outside the city, where the cost of living was lower. (Hippies were perennially broke.)

On a growing number of rural communes, hippies joined disaffected political radicals and Vietnam draft dodgers in embracing back-to-the-land living, including free love, organic farming, vegetarianism, holistic medicine and a lot of marijuana use.

Among the various groups that made up the vibrant ‘60s counterculture in the United States—including the civil rights movement, the Black Panthers, gay rights and women’s liberation activists, anarchists and other political radicals—hippies stood out for their relative lack of a distinct political ideology. Hippie politics was more a “politics of no politics,” Rorabaugh says. “One of the things hippies said was 'you should do your own thing, you should do whatever you feel like doing.'”

All the same, it’s no accident that the path of the hippie movement that emerged in the late ‘60s traced very closely the trajectory of American involvement in Vietnam. Hippies saw mainstream authority as the origin of all society’s ills, which included the war. According to Rorabaugh, hippies joined with political radicals in their support for the civil rights movement and their opposition to the Vietnam War. “Hippies would agree with that, but they would not protest,” he points out. “That was the difference—hippies were not protesters.”

The most identifiably political hippie group was the Diggers, an anarchist organization formed in 1966 in San Francisco. They were known for passing out free food to the hippies panhandling in Golden Gate Park, and operating a free store (stocked with stolen goods) that would provide clothing for draft dodgers and AWOL soldiers seeking to go incognito. Like the Diggers, the Yippies, or the Youth International Party (YIP) founded in early 1968, also tried to attract hippies to politics, with little success.

In addition to the Summer of Love, that hippie heyday in 1967 when some 100,000 people from around the country converged on Haight-Ashbury, the most famous celebration of hippie counterculture occurred in August 1969 at the Woodstock Music Festival. Advertised as “three days of peace, music and love,” Woodstock “brought both political people and counterculture people together,” Rorabaugh says. Indeed, somewhere between 300,000 and 400,000 people, far more than its organizers originally expected, flocked to upstate New York to hear artists like Joan Baez, The Grateful Dead, Jimi Hendrix, Janis Joplin, Jefferson Airplane, The Who, Crosby, Stills, Nash & Young and Creedence Clearwater Revival play the music that fueled the hippie movement.

In some ways, the Summer of Love also marked the beginning of the end for the hippie movement, as drugs, homelessness and crime had infested Haight-Ashbury, pushing out many of the neighborhood’s original residents. In October 1967, the Diggers held a “Death of the Hippie March” in San Francisco to decry the commercialization of hippie culture. The march ended at the famed Psychedelic Shop, an early hippie hangout that was closing. Marchers buried the shop’s signs, marking a symbolic death for the hippie heyday.

On November 15, 1969, several months after Woodstock, growing opposition to the Vietnam War culminated in the largest antiwar demonstration in U.S. history, with as many as half a million people attending a protest in Washington, D.C., in addition to smaller protests around the country. A month later, violence broke out at another hippie gathering, the Altamont Music Festival, leaving five people dead. When combined with other acts of violence, including the gruesome Manson Murders of 1969 and the National Guard shootings of students at Kent State in 1970, Altamont brought the free-wheeling attitudes of the “love generation” crashing down into a more sordid reality.

By the time U.S. participation in the Vietnam War ended in 1973, the media had largely lost interest in the hippie movement, even though many of the hippies’ formerly radical style choices (beards, sideburns and long hair on men, for example) had been adopted by mainstream American culture. But the communes, which endured until the mid-’70s and even longer, in some cases, would be the source of many of the hippies’ lasting legacies, including pro-environmental attitudes and practices that are still very much in force today.

"Natural food, organic food, eating local, co-op groceries—all of that came out of the communes,” Rorabaugh says. “Also a looser style of child-rearing, and more casual attitudes about sex. And solar panels—Northern California hippie communes were the first people to have solar panels in 1970. They did it because they needed some hot water for washing dishes. They were off the grid, and they didn't want anything to do with the utility company."

Though some hippies remained committed to the lifestyle for the long haul, many others assimilated themselves into the mainstream culture they had once despised. Perhaps the most famous of these, Rorabaugh says, was Steve Jobs, founder of Apple.

Jobs, who embraced Buddhism after a trip to India in the early ‘70s, “conceived of the idea of personal computer as putting computer power in the hands of ordinary people, and taking it away from IBM,” as Rorabaugh puts it. “Taking computer power away from giant corporations and giving it to ordinary people”—what could be more anti-establishment than that?