John Mack Carter’s office was comfortable, as befitted the editor-in-chief of one of the nation’s most important women’s magazines. But on March 18, 1970, there was nothing comfortable about it.

Suddenly, his office and the rest of the New York headquarters of the Ladies’ Home Journal was occupied by over 100 women—outraged feminists demanding a change in how the media portrayed women. For the next 11 hours, they’d engage in a raucous standoff with magazine staff, bringing the magazine’s motto, “Never Underestimate the Power of a Woman” into an unexpected light. And along the way, they’d help change media portrayals of women and women’s issues.

At the time, the Ladies’ Home Journal was the second most-read magazine in the country, boasting 14 million monthly readers and holding a coveted spot in the constellation of periodicals. It was written for women, but was owned and operated largely by men.

Gloria Steinem, who occasionally wrote and consulted for the Journal, writes that one of the magazine’s editors “was so convinced that I was nothing like its readers (whom he described as ‘mental defectives with curlers in their hair’) that he used to hand me a magazine and say ‘Pretend you’re a woman and read this.’”

Feminists felt this attitude reflected in the magazine’s content, which focused primarily on beauty, homemaking and motherhood. One of the magazine’s most famous features was its “Can This Marriage Be Saved?” column, in which troubled wives were given advice on how to rescue marriages that were often physically and emotionally abusive. Often, writes Rebecca Onion, wives were blamed for their problems and told to better serve their husbands’ needs.

This infuriated activists in the nascent women’s liberation movement, as did the magazine’s insistence on what they saw as outdated beauty standards and oppressive roles. With the dawn of the sexual revolution and the social upheaval of the 1960s, women’s lives had changed dramatically. The Journal’s pages didn’t really reflect those changes, charged feminist activists. In fact, it barely mentioned feminism at all, focusing instead on the joys of motherhood, domestic subservience and housekeeping.

In early 1970, members of a variety of women’s organizations including the National Organization for Women, the Redstockings and the New York Radical Feminists, decided they’d had enough of women’s magazines. They met to brainstorm ways to draw attention to the industry’s sexism, and when they realized that one member was an ex-employee of the Journaland still had access to the building, they decided it was the perfect target.

“It was ludicrous that men were running the magazine by a formula that said that women should be happy housewives,”says Susan Brownmiller, who helped organized the sit-in. She was among the first who went into the office. Soon, nearly 200 women had done so, too.

Their main target was editor-in-chief John Mack Carter, who engaged in a series of tense arguments with the activists. Their demands were many: They wanted Carter to step down in favor of a woman editor, an advertising and editorial staff of all women, free daycare for employees, an editorial policy against ads that were exploitative of women, and an end to the “Can This Marriage Be Saved?” column.

“How do I know you’re serious?” Carter reportedly asked. Over the next 11 hours, the protesters convinced him they were. They argued with Carter and Lenore Hershey, the only senior female editor on staff, about the magazine’s content, advertising, and employment practices. They smoked Carter’s cigars and tried to “liberate” his desk by pushing him off of it. (Carter sat casually against the desk all day.) They showered him with article ideas for pieces entitled “How to Get an Abortion” and “How Psychiatrist Hurt Women—and Why” and tussled with the media, who had begun to arrive in droves.

The protest wasn’t entirely peaceful: At one point, a cameraman hit a woman and was kicked out of the office; at another point one of the activists lunged for Carter and had to be talked down. It soon became clear that the sit-in would be a matter of endurance. Some protesters spoke with members of the staff, not all of whom were sympathetic. “Turn yourself off, baby,” the magazine’s male research editor told protesters. “If you don’t like the magazine, don’t read it.”

Others got down to brass tacks with Carter. Though he initially refused to negotiate, he soon realized the media opportunity presented by the sit-in and started to listen to demands for a woman-produced edition of the magazine. By nighttime, the deal was finalized: An eight-page section entirely produced by protesters and a promise to consider on-site daycare.

Finally the protesters left the office, exhausted, but confident their publicity stunt had succeeded and that it would get wide media coverage. “It got more publicity than anything leading up to that time in the women’s movement,” says Brownmiller. They also saw promise in the section they would write and edit.

In August 1970, it appeared. It included pieces with titles like “Should This Marriage Be Saved?” “Your Daughter’s Education” and “Babies Are Born, Not Delivered.” The content was radically different than anything that had ever appeared in the Journal’s pages: It celebrated the female body, outlined discrimination and sexism, and decried housework as “domestic slavery.”

So how did the magazine’s readers respond to the Journal’s newly liberated pages? As historian Jean E. Hunter notes, response was mixed. The magazine received a torrent of letters, some supportive of the protesters, some appalled. Though 34 percent supported the feminists, writes Hunter, 46 percent were against the movement. The content “would have shocked any readers who had depended on the pages of the Journal for their understanding of the changes occurring in women’s roles,” Hunter writes. “And shocked they were.”

Though the Journal didn’t drop its male leadership or its articles about fashion and housekeeping, it increasingly covered women’s issues over the coming years. But so did its counterparts—in part because of the raucous visibility of the feminist movement, in part because attitudes toward women were changing.

Carter, himself, would eventually say that the sit-in marked a turning point in his view on the tone and role of women’s magazines. The protesters may not have liberated the Ladies’ Home Journal, but they did help change perceptions of how the media could portray women’s lives.