In the end, Clinton decided to make the trip, hoping to “push the envelope as far as I can on behalf of women and girls”.

“All eyes were now on Beijing, and I knew that all eyes would be on me, too,” she writes in her memoir, Living History.

But as she rose to the podium, and even after she had stepped down to thunderous applause, Clinton had no idea the impact the moment would have, she says. More than two decades later, that 21-minute speech — with its declaration that “Human rights are women’s rights, and women’s rights are human rights” — remains one of her signature moments in public life.

It also stands out as a moment Clinton began to truly forge an identity as a public figure on the world stage apart from her husband.

“It gave her a platform that was instantly recognisable, one that she could utilise in a very efficacious way to make a difference,” says Melanne Verveer, Clinton’s chief of staff at the time.

And while Clinton was no stranger to the subject she addressed — she had long been an advocate for women and children — the Beijing speech would set a course for the issues with which she would be involved for the rest of her career, especially as secretary of state, says Verveer, who later served as the first US ambassador-at-large for global women’s issues.

“It played a major role in who she would become. It really was one of those evolutionary, transformative moments.”

And it almost didn’t happen. A few months earlier, Chinese-American dissident Harry Wu had been arrested upon entering China and charged with espionage, throwing the participation of the US delegation and Clinton, its honorary chair, into limbo. He was finally released less than a month before the conference; Clinton writes that there was “never a quid pro quo.”

She and her aides flew from Hawaii, where President Bill Clinton was speaking on the anniversary of V-J Day at Pearl Harbour. Working on the draft while others slept, the group was keenly aware that “one wrong word in this speech might lead to a diplomatic brouhaha,” Clinton writes.

Hours later, she took the microphone in the large hall. She began by telling the delegates that when women are healthy, educated and free from violence, with a chance to work and learn, their families flourish, too. About halfway through, she declared: “It’s time to break the silence. It’s time for us to say here, for the world to hear, that it is no longer acceptable to discuss women’s rights as separate from human rights.”

With emphasis on the word “human” each time, she listed abuses against women — and called them human rights violations (she did not mention China by name). Then came her most famous line: “If there is one message that echoes forth from this conference, let it be that human rights are women’s rights, and women’s rights are human rights, once and for all.”

Once the words had been translated for all to digest, the reaction was thunderous. “People have tears running down their cheeks, they’re stomping their feet,” Verveer recalls. In her memoir, Clinton writes that despite the reaction, she still had no idea “that my 21-minute speech would become a manifesto for women all over the world.”

It’s difficult to understand in 2016 just how new Clinton’s message felt, says Kathy Spillar, executive director of the Feminist Majority Foundation.

“We look back 21 years later, and we go, ‘duh’ — but it was groundbreaking at the time,” she says. “It was huge — the first lady of the United States saying this, just outright. Many women were coming from countries where discrimination against women disguised as cultural practice was widely happening. Even the U.N. as a whole hadn’t embraced this agenda. ... It was just an extraordinary moment in the centuries-long struggle for women’s full human rights around the world.”

But does the moment resonate for younger generations? Clinton’s presidential campaign has struggled — especially during the primary season against Vermont Senator Bernie Sanders — to capture the enthusiasm of young voters.

“For millennials and the 18-30 group, it does seem like ancient history,” says Debbie Walsh of the Centre for American Women and Politics at Rutgers University. “But I think that when that speech is played and those words are heard, they’re still meaningful. The global issues are not solved, and I think they do resonate with young women. So teaching young women in particular about Beijing — and what a departure it was from most first ladies to do something like that — is an important message for the Clinton campaign.”

Writer Andi Zeisler was in her early 20s at the time, and she remembers news of the Beijing speech coming in stark contrast to more negative coverage of Hillary Clinton, especially when her husband was running for president.

“Hillary had become a focal point in so many ways, almost all of which were negative — the fact that she didn’t give up her career ... this whole phenomenon of Hillary Clinton as a first lady considered too big for her britches or uppity or unforgivably ambitious,” says Zeisler.

And so the Beijing speech amounted to “seeing her find a place where her voice was welcomed and where she kind of fit,” says Zeisler, 43, author of We Were Feminists Once and co-founder and editorial director of the nonprofit Bitch Media. “I always think of the Beijing speech in the context of the word ‘empowerment’ because it was one of the first places on a global level where empowerment as an agenda — and as something that we should be striving for — was brought up.

“It was such an obvious thing: Women’s rights are human rights. It seemed self-evident. But that was a real bombshell for a lot of people,” she says.

Reminders of the moment have arisen often in Clinton’s global travels, Verveer says.

“Even today if somebody comes up to her who remembers, they’ll introduce themselves,” she says. “They’ll say, ‘I was in Beijing.’ It’s that instant recognition that they shared something.”