Sunday was a historic day for the intersection of sports and politics.

Widespread protests in the National Football League, the most popular professional sport in America, were shown on broadcast channels across the country.

Stick to sports? Not this week. Whether sports fans wanted to see it or not, they couldn't avoid politics.

Athletes — mostly black — from every team in the country knelt, stood arm in arm, sat or refused to take the field for the national anthem. They even took it abroad with the first protest taking place in England, in a game that represents the NFL's effort to broaden the league's appeal.

And it's all because of President Trump.

"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a bitch off the field right now'? "He's fired!" Trump said at a political rally in Alabama, referring to NFL players who have knelt or sat in protest of social injustices, particularly in communities of color, as the national anthem has played.

Former San Francisco 49ers quarterback Colin Kaepernick was the first to make the controversial statement last year, before Trump's election, over police violence in black communities. The practice seemed to be fading in the NFL — until Trump weighed in.

Trump has given it new life. It has become about freedom of speech — and something of a galvanizing anti-Trump protest.

The Alabama crowd ate it up. Trump was there to promote his preferred candidate, Luther Strange, in the Alabama Republican primary runoff taking place Tuesday. Strange later said he thinks the comments could help him win the primary. He is running against an even better known culture warrior in former Alabama Supreme Court Justice Roy Moore.

Trump's continued focus on the issue — 15 tweets between Saturday and Monday morning — could very well help his preferred candidate in the short term. It also could have the effect of keeping his base unified while he tries to work with Democrats and another GOP health care bill is on the verge of collapsing.

(This weekend also saw officials in Puerto Rico crying out for help in its attempts at recovery after Hurricane Maria. While FEMA issued a press release laying out all it is trying to do for the American island, President Trump tweeted zero times about the crisis there.)

But this is bigger than who becomes the next Alabama senator. This is about where this moment in history, with a president like President Trump at the helm of the country, fits in. It's another chapter in a divisive history of sports, politics and race.

"This has nothing to do with race"

Trump told reporters in New Jersey Sunday, "No, this has nothing to do with race," when asked if he was inflaming racial tension. "I've never said anything about race. This has nothing to do with race or anything else. This has to do with respect for our country and respect for our flag."

And Trump has plenty of like-minded Americans — and football fans — with him.

"It's disgusting," one woman told a Fox News reporter at the New York Jets-Miami Dolphins game Sunday. She also said what the players were doing was "unethical" and a "disgrace."

Another woman said, "They're paying these guys to do a job. They're not supposed to be involved in politics."

That sentiment could be found across social media, from Twitter to Facebook.

A Quinnipiac Poll last year found that, by a 54-to-38-percent margin, most Americans disagree with NFL players refusing to stand for the anthem.

But there was a huge racial divide. Almost two-thirds of whites disapproved of not standing for the anthem, while three-quarters of African-Americans approved of the tactic.

And that might fundamentally be because of a disagreement over the core issue of the original Kaepernick protest — police violence in black communities. The same poll found 70 percent of whites approve of the job the police are doing, while two-thirds of blacks do not.

Athletes in the NFL are overwhelmingly black — 70 percent of the league, in fact.

A long and complicated history of black athletes protesting in sports

Athletes, especially black athletes, have used the megaphone sports provides to protest for a long time.

Jesse Owens and 17 other black American Olympians went into the 1936 Olympics in Germany and won medal after medal in front of Adolf Hitler. (Two American Jewish runners, however — Marty Glickman and Sam Stoller — were denied the chance to run because of Nazi opposition that the U.S. Olympic Committee acquiesced to.)

Those 18 black athletes accounted for a quarter of the entire U.S. team's medals in Berlin. But nearly all faced racism, backlash and a lack of fully integrated rights as citizens back home in a segregated America.

Thirty-two years later, Tommie Smith and John Carlos, American gold and bronze medal winners at the 1968 Olympic Games, donned black gloves and raised their arms in a black power salute from the medal podium in Mexico City. (Australian runner Peter Norman, who is white and won the silver, wore an Olympic Project for Human Rights badge in support of their efforts.)

Consider the time: 1968 was another inflection point year in American political and social history. Violence was spilling out in the civil rights and integration movement. Cities had been burned from rioting the year before. Martin Luther King Jr. and Robert F. Kennedy had been assassinated.

Like today, the country was divided politically and along racial lines.

Smith and Carlos, too, were met with opposition to their podium statement. The U.S. Olympic Committee, in fact, sent Owens to Mexico City to try to persuade them not to do it. He was unsuccessful. After their wins, they were stripped of their medals by the head of the International Olympic Committee.

Norman went home to Australia and was banished from participating in another Olympics and any involvement with that country's Olympic teams. It wasn't until after his death that the Australian government passed a resolution honoring Norman for standing up for human rights. Smith and Carlos were pallbearers at Norman's funeral.

Of course, there was Muhammad Ali. Born Cassius Clay, the champion boxer converted to Islam in 1964, and when drafted into the Vietnam War in 1967, he refused to go, citing religious convictions. Ali was convicted of draft evasion, sentenced to five years in prison and banned from boxing for three years. The U.S. Supreme Court overturned his conviction in 1971.

Around the same time, Curt Flood of the St. Louis Cardinals made history in 1969 by challenging a clause in professional baseball that essentially said players were teams' property. Flood called himself a " well-paid slave." That triggered mass backlash among whites, but it also helped bring the issue of free agency to the forefront.

Flood's case went to the Supreme Court, where he lost 5-3, but half a dozen years later, an arbitrator went against the Supreme Court's ruling and modern free agency was born. The NFL adopted similar free agency in 1992 and the NBA, the professional basketball league, in 1996.

Flood, though, never benefited from the sports revolution he spurred. After the Supreme Court decision, he was accused of trying to destroy the sport and received multiple death threats a day. It all proved too much, and he left the country, opening a bar in Spain.

"Plagued by increasing debt, including unpaid child support, and guilt that he had been a bad father, Flood was finally admitted into a Barcelona psychiatric hospital," The Atlantic wrote.

Eventually, Flood was embraced by the sport he fled. He returned to the U.S. and received the 1992 Jackie Robinson Award for contributions by black athletes, and in 1994, he received a standing ovation from players after a speech he made about solidarity before their strike that year.

It often takes guts and courage to protest, because protest means you're standing against something others believe in — or entrenched traditions, which can be extremely difficult to change. Almost universally, the athletes who have stood against what they see as injustice suffered social and economic consequences, not seeing the benefit personally that their efforts led to for others.

Kaepernick still hasn't landed a job in the NFL, despite analysts saying he is at least good enough to be a backup — and that he is playing in a league that has tolerated accused domestic abusers, those arrested for assault and battery, a star who organized dogfighting and much more. (See USA Today's database of hundreds of NFL player arrests.)

Purposeful distraction and politics of the personal?

If Trump hadn't captured the attention of the country by inserting himself into another culture war, the narrative over the weekend might have been dominated instead by Arizona Sen. John McCain imperiling yet another Republican effort at repealing and replacing Obamacare, the unifying issue for conservatives in the Obama era.

Instead, Trump's focus was on the NFL, a league with which he has had a charged relationship over the years. In the 1980s, Trump believed he could undermine the NFL and start his own league — the USFL. The league lasted only three seasons, and Trump is blamed for its demise — notably by trying to go head to head with the NFL by moving the season to the fall.

It was widely believed that Trump was trying to make the USFL enough of a player to win a merger with the NFL and have his entree into the league as an owner. It's something he never gave up but never succeeded at. He tried to buy the Buffalo Bills, for example, in 2014, lost out and was bitter about it.

He took to Twitter to say the price was " ridiculous," the team wouldn't be a "winner," trash-talked the new owner (also the owner of the Buffalo Sabres hockey team) and complained that the NFL was too "soft," anyway.

It's always personal with Trump, so don't lose sight of that in this current controversy.

But what he did calling players "sons of bitches," questioning their patriotism (and right to free speech) and calling for their firings, struck a nerve and had an ironic unifying effect across the league.

Owners stood with players arm in arm. Dan Snyder, the owner of Washington, D.C.'s football team, for example — a Trump supporter who donated $100,000 to help elect him and $1 million to his inaugural committee — stood on the field, arms locked, with star cornerback Josh Norman, who has been hotly critical of Trump.

"What president?" Norman asked rhetorically after Washington's 27-10 win over the Oakland Raiders Sunday night. "Not my president. He was chosen, true. But when a president acts like that, what do you say to that? That's not someone that stands with dignity, pride, respect, honor. Where's the honor in that? Where's the dignity in that? Where is anything that's prideful in doing what you did? Words are powerful. They can either unite you, or they can divide you. So what he said united us."

Norman went on to say that Trump was "not welcome in Washington, D.C."

Even Patriots owner Bob Kraft, who gave Trump a Super Bowl ring, and quarterback Tom Brady, who was spotted with a Make America Great Again hat in his locker last year, said they disagreed with Trump.

Trump's comments may help to solidify his base and possibly distract from things that they might get upset about (like not being able to repeal Obamacare or trying to work with Democrats), but it is a curious political move.

The remarks landed him right back into the race and culture wars, just a month after his widely criticized response to white supremacists, Nazis and the KKK marching in Charlottesville, Va. And his handling of race relations, Charlottesville and Twitter, are three of the least popular things Trump has done, an NBC/WSJ poll found last week.

For Trump, he says this is not about race – despite his track record of how he waged his campaign and whom he has chosen to insult. Many conservatives agree with him — that regardless of your views, you should be proud of the country.

That was the case for Alejandro Villanueva, a star lineman on the Pittsburgh Steelers, who was the only Steeler to go out on the field for the anthem. Villanueva is a former Army Ranger and Bronze Star recipient. His choice became a meme for conservatives, and #AlejandroVillanueva was trending on Twitter. The choice for players not to go on the field was backed up by Steelers coach Mike Tomlin.

But life is often more complicated than the "Hero" and "Villain" memes of the Internet. Villanueva has said he is also supportive of athletes speaking out on social injustice, but for him, the flag and his service give him a different perspective.

That's not everyone's experience. Certainly, many black athletes ( and African-American military members), aware of history, come at it from a different place.

"One brother, you mess with one, you mess with all," Washington's Norman said Sunday night. "Nobody's divided in this."

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