When Olympic sprinters Tommie Smith and John Carlos stood atop the medal podium at the 1968 Summer Games in Mexico City, bowed their heads and raised black-gloved fists during the playing of the national anthem, millions of their fellow Americans were outraged. But countless millions more around the globe thrilled to the sight of two men standing before the world, unafraid, expressing disillusionment with a nation that so often fell, and still falls, so short of its promise.
In tribute to Smith, Carlos and every other athlete—Eric Liddell, Curt Flood, Sandy Koufax and on and on—who has acted on principle in a highly public way, LIFE.com presents John Dominis's indelible portrait of that moment.
Smith and Carlos (both of whom are National Track and Field Hall of Famers) were vilified at home for their stand. They were suspended from the U.S. team. They received death threats. But neither man ever apologized for his raised fist or his bowed head—and neither ever had need to.
"We were just human beings who saw a need to bring attention to the inequality in our country," Smith said years later, in a documentary on the 1968 Mexico City games produced for HBO. "I don't like the idea of people looking at it as negative. There was nothing but a raised fist in the air and a bowed head, acknowledging the American flag—not symbolizing a hatred for it."
Finally, it's worth noting that the Australian silver medalist in the 200 meters in 1968, Peter Norman, stood solidly with Smith and Carlos, both literally and figuratively—displaying his solidarity with their action by wearing an Olympic Project for Human Rights badge during the medal ceremony. Four decades later, in 2006, both Smith and Carlos were pallbearers at Norman's funeral.
"We knew that what we were going to do was far greater than any athletic feat," Carlos was quoted as saying at the time. "[Peter] said, 'I'll stand with you.'"
Carlos expected to see fear in Peter Norman's eyes before the medal ceremony, when there was no turning back from what they were about to do. But he didn't see fear.
"I saw love," he said.