The Democratic National Convention was a tense scene in July of 1972. The gathering in Miami came just one month after burglars had broken into the Democratic headquarters at the Watergate. The candidate who won the presidential nomination would be the one to take on President Richard Nixon, whom most people didn’t yet suspect of orchestrating the break-in. And for the first time, one of the candidates for the Democratic challenger was a black woman.

Shirley Chisholm had long been known for breaking barriers. Four years before, she’d become the first black U.S. Congresswoman in history as a Representative of her New York district. When she launched her primary campaign in January of ‘72, she became the first black person to seek the presidential nomination from one of the two major parties (the first woman was Margaret Chase Smith, who sought the Republican nomination in 1964). Her slogan was: “Unbought and Unbossed.”

Shirley Chisholm campaign poster. Collection of the Smithsonian National Museum of African American History and Culture, Gifted with pride from Ellen Brooks

From the beginning, white male journalists and politicians didn’t take her bid seriously. Norman Mailer called her campaign “quixotic” in the Wall Street Journal, writing that “few politicians, black or white, believe it.” Chisholm’s strongest supporters were black women, but she struggled to win support from black men and white women. Many of them endorsed Senator George McGovern because they felt he was more likely to win against Nixon. (McGovern won the nomination and lost to Nixon in a landslide.)

Chisholm was realistic about her chances, and winning wasn’t necessarily her goal, says Anastasia Curwood, a professor of history and African American and Africana studies at the University of Kentucky who is writing a biography about Chisholm.

“She ran to win, but she knew she wouldn’t win,” she says. “Her object was to create a coalition and then influence the eventual nominee at the convention.” Chisholm hoped that once she reached the convention, she could could use her coalition of delegates to negotiate with the winning candidate in favor of rights for women, black Americans and Native people.

Shirley Chisholm oannouncing her entry for Democratic nomination for the presidency, at the Concord Baptist Church in Brooklyn, New York in January 1972. Don Hogan Charles/New York Times Co./Getty Images

Her opponents were all white men, but there was one in particular who stood out in relation to her: George Wallace, the former governor of Alabama who famously called for “segregation now, segregation tomorrow and segregation forever.” It was incredible that a black woman and the man who had been the face of southern segregation were competing in the same primary.

On the campaign trail, Chisholm’s “rhetoric implicitly rejected what he stood for,” says Curwood. She didn’t directly point to Wallace, but he did sometimes mention her.

“George Wallace for some strange unknown reason, he liked me,” Chisholm later said. “George Wallace came down to Florida and he went all over Florida and he said to the people, ‘if you all can’t vote for me, don't vote for those oval-headed lizards. Vote for Shirley Chisholm!’ And that crashed my votes, because they thought that I was in league with him to get votes. That’s what killed me in Florida.”

Wallace’s Democratic primary campaign effectively ended in May, when he was shot five times in a failed assassination attempt. The shooting of someone running in the same race—and the fact that it could’ve happened to her—rattled Chisholm, Curwood says. Chisholm visited Wallace in the hospital, a move that angered a lot of her supporters.

George Wallace and his wife Cornelia, holding up a newspaper indicating his victories in the May 16 Maryland and Michigan Democratic Presidential primaries, now paralyzed from the waist down by one one of four gunshot wounds suffered while campaigning.. Bettmann Archive/Getty Images

In July, Chisholm arrived at the Democratic convention with 152 delegates. This was more than those of senator Hubert Humphrey and Edward Muskie, who’d been two of the main challengers on the campaign trail (Humphrey was the Democratic candidate in 1968). Yet she was still in fourth place behind Senator George McGovern, Senator Henry Jackson, and the injured Wallace. McGovern was the clear winner with 1,729 delegates, and his lead gave him no incentive to negotiate with Chisholm for her 152.

Even though she wasn’t able to use her delegates as leverage, Chisholm knew her candidacy was necessary in shifting the paradigm in which the only white men could be considered presidential material. Her presidential run was met with hostility from racists who vandalized her campaign materials with the n-word and men who told the Chicago Daily Defender she was playing “vaginal politics." But her candidacy opened the door for other black and female candidates to run for president.

“She said many times, I just want to show it can be done,” Curwood says. Chisholm died in 2005, three years before Barack Obama became the first black president and nine years before Hillary Clinton became the first female nominee for one of the two major parties.

“The fact that [Chisholm] got as far as she did is pretty remarkable,” Curwood says. Still, she thinks Chisholm “would have been stunned by how long it took” to get to Obama and Clinton’s milestones.