"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of colour,” he said after making his first protest before playing for the San Francisco 49ers.

"To me, this is bigger than football and it would be selfish on my part to look the other way.”

He added that he would continue to protest until he felt like "the American flag represents what it's supposed to represent".

So we move on two years. Kaepernick - no longer a National Football League (NFL) player and now taking legal action against NFL team owners - is the face of Nike’s new advertising campaign.

As you might expect, and as Nike have doubtless fully anticipated, opinion has polarised on this.

Nike are unlikely to have let their hearts rule their calculators here. They will have taken a cool, commercial view that there will be more people wanting to buy their goods because of this collaboration than there will be people wanting to burn their goods in protest at what they see as a sleight on the US flag.

Members of the US military are among those who have combusted Nike goods. But other members of the US military have been tweeting that they see their service as fighting for the right to ensure that there can always be Kaepernick-style protests in the land of the free.

He takes his place in a line of black sports people who have put themselves on the line to protest against the injustices they see in their society - such as basketball player LeBron James, such as the former world heavyweight boxing champion Muhammad Ali, such as US Olympic sprinters Tommie Smith and John Carlos at the 1968 Mexico Olympics.

What is happening now in reaction to Kaepernick is following a classic pattern.

Ali was stripped of his titles and was unable to box for four years at what would have been the height of his career as he appealed, eventually successfully, against the threat of a jail sentence for refusing the draft for religious reasons.

Smith and Carlos were ostracised by US Olympic officials, their sporting careers effectively ended the moment they climbed onto the podium after winning gold and bronze in the 200 metres at the 1968 Mexico Olympics and made their famous/infamous gesture of solidarity and support for victimised fellow black citizens in their society by raising a single, black-gloved fist each.

The original plan had been for each to have a pair of black gloves but they had left a pair in the Athletes’ Village, and it was at the suggestion of the Australian silver medallist Peter Norman, who was also vilified by his own sporting establishment for “standing with” the two Americans, that they took a single glove each.

They were also barefoot as a protest against poverty and they wore beads as a reference to protest against lynchings. All three on the podium wore badges proclaiming the Olympic Project for Human Rights.

The protest by Smith and Carlos was seen as aggressive and politically inflammatory by the United States Olympic Committee, and they were suspended from the US team by the then International Olympic Committee President Avery Brundage.

There followed death threats, and years of economic hardship.

Coincidentally Wyomia Tyus, the US sprinter who became the first athlete to win successive Olympic 100m titles, following up her Tokyo 1964 triumph with victory in Mexico four years later, has just released her autobiography, “Tigerbelle: Tigerbelle: The Wyomia Tyus Story,”.

In it she recalls the shock of witnessing the protest staged by Smith and Carlos – and the rapid polarisation of opinion it provoked.

In an extended excerpt from her book run by NBC Sports in their Olympic Talk section she recalls how, as she watched the podium protest, her thoughts immediately turned to concern for the two athletes as she began looking around and above where she was watching to see if anybody was trying to do anything “retaliatory".

She adds: “Because while some people were cheering, some people were booing. They were angry. You could see it in their faces. And I kept thinking, I just want to be out of here. Because I didn’t know what was going to happen.

“I thought: That was so powerful and It’s going to strike so many people the wrong way and I hope nobody hurts them. That was one of my first thoughts: I hope no one hurts them.”

Afterwards she details how, at a US team meeting in the Village, the strong rumour was that Smith and Carlos would be sent home and have their medals taken away, although the latter action never came to pass.

But then Tyus recalls a second meeting at which other black athletes felt the message was: “You can do whatever you want. What they have done, that said everything right there.”

Some of the men on the relay teams wore berets. Others wore black socks, shorts, and armbands. Long jumper Ralph Boston went to the podium barefoot to collect his bronze medal.

Tyus recalls how she herself wore black running shorts in the subsequent 4x100m relay fiinal, where she ran the anchor leg as the US won in a world record of 42.88sec, although she adds that she wasn’t sure anyone had noticed.

But when the team were asked afterwards by the press what they thought about the Smith and Carlos protest, Tyus replied: “What is there to think? They made a statement.

“We all know that we’re fighting for human rights. That’s what they stood for on the victory stand - human rights for everyone, everywhere. And to support that and to support them, I’m dedicating my medal to them. I believe in what they did.”

In the 1999 HBO documentary Fists of Freedom: The Story of the '68 Summer Games Smith reflected: We were not Antichrists. 

"We were just human beings who saw a need to bring attention to the inequality in our country.

“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 symbolising a hatred for it.”