Every generation, every nation, has an iconic moment. For the American civil rights movement that moment was when Dr Martin Luther King Jnr delivered his I Have a Dream speech during a march on Washington DC on August 28 1963.

For the boxing world I want to argue that one of those moments of greatness came in 1965 when Muhammad Ali floored the unbeaten heavyweight behemoth Sonny Liston in the first round in one of the most memorable upsets in Lewiston, Maine.

For South Africa, that historic milestone is what I want to call the "Sam Nzima Moment". Sam who? Not many people know who Nzima was. Even though Nzima, 42 at that time, was not a headline-grabbing photographer, he did not sleep on the job - in other words, he knew what "time it was", to use the slang of the era.

As a staff photographer at the premier black daily newspaper The World, he was one of a few journalists who'd been tipped off that "something big" was going to happen on the streets of Soweto on June 16 in 1976.

Just how big that "something" was going to be was anyone's guess.

When Nzima arrived at Naledi High School around 6am in the morning, students had already massed outside the premises, preparing placards that bore such messages as: "Away with Afrikaans", "We are Being Certified but not Educated."

Even then, Nzima felt a thick sense of foreboding.

It did not take long before students started bursting forth into the streets, chanting slogans and waving their placards. Some aerial photos taken by the police at the time show the viewer what appears to be humongous caterpillars writhing through the landscape.

They were not caterpillars, those were children. Tens of thousands of them running in the streets, towards a prearranged destination.

They were not to get there. Because the police suddenly appeared. At the corner of Moema and Vilakazi streets in Orlando West there was a bang. The children scattered. There were screams. A young man in delela dungarees emerged from the crowd, carrying a limp body of a boy in full school uniform.

Then a girl appeared, shouting at the young man to let go of her brother. Nzima had been clicking away all along, capturing the action.

The following day the world woke up to the horror of the June 16 massacre as documented by Nzima.

The young man who'd been carrying a boy was later identified as Mbuyisa Makhubu, the boy was 13-year-old Hector Pieterson, and the girl was Hector's 17-year-old sister Antoinette.

Thanks to this image, the world could no longer ignore the horror of apartheid. The US condemned the shooting, and activists worldwide began lobbying for economic sanctions, which eventually brought the apartheid government to its knees.

For Nzima, the picture brought mixed feelings: while he became an international celebrity, in apartheid South Africa he became one of the state's enemies. He was harassed by the security police who wanted to know what had happened to Makhubu.

Nzima had to quit his job, leave Johannesburg and seek refuge in the homeland of Gazankulu. In 1978 The World was shut down.

Though the picture was iconic, Nzima did not realise material benefits from its publication, as copyright resided with the company which employed him.

Nzima's son Thulani said this week that although it took his family 22 years to consolidate his father's rights to the Hector Pieterson image, it gave the family pleasure knowing his father lived to experience the global recognition he received for his selfless contribution.

Born in 1934, Nzima died last Saturday in Nelspruit.

We dare not forget him.