Whoever put the noose in Bubba Wallace’s garage gave Nascar and all the rest of us permission to quit our romance with the rebel South, to finally leave that doomed relationship, with its phoney harlot beauty. The stock car drivers who marched on the track at Talladega Superspeedway had a certainty in their step that felt momentous. They weren’t just walking with Wallace. They were walking away from something: a past.Kyle Busch was there, and Kevin Harvick, and team owner Richard Petty was, too, right alongside the No 43 car to catch Wallace when he came out of it weeping, overcome by the gesture of brotherhood. They streamed out of the garage, 40 drivers and their crew members in various decals and colours, in support of the man who persuaded Nascar to ban the Confederate flag from its tracks. They all headed in the same direction: away from an old attitude, from not-my-problemism and casual easy acceptance, but towards what promises to be a fight with a certain hard base of their audience, and perhaps some insiders, too.Understand this: that flag isn’t going away. As author John Coski writes in his book The History of the Confederate Battle Flag, it is not “an alien symbol grafted on to the American tradition and is not therefore simply going to disappear. The people who fly or revere the flag will not become extinct, and they will resist efforts to re-educate them to view it as offensive”.The question of why so many people wave it so tenaciously is not easily answered, either. It has become associated with multiple meanings, some of which are difficult to uproot. To one segment, it represents the “defence of constitutional liberty against Big Government,” Coski suggests. For others, the soldierly valour of an ancestor. Such people “resent the categorical denunciation of it as only a symbol of slavery and racism,” he observes.But as that noose showed, it is impossible to separate the battle flag from its original cause, to pull blameless threads from it or sew milder meanings into it. Nascar drivers understood that, right then and there at Talladega, and acted with a powerful reflexiveness. But their work going forward will be slower, and harder. The drivers will have to explain, with their inimitable combination of intelligence and common touch and Southern roots, to a portion of their fans why they don’t want the Dixie flag around them any more.That’s as much an opportunity as a problem. Seldom has a sports league had the chance to reach an audience with a bolt of truth and change common perceptions of a cultural article. Nascar’s leaders are going to have to be good history teachers if they plan to articulate why it’s an unfit companion at events that fly the stars and stripes.Southerners may think they know everything about that flag, but too many of them don’t know the half of it. The hothead sovereigns of the Confederate states actually cycled through three banners over the course of the war to symbolise what they fought for. For a time, they used something called “the stainless flag”. It had the southern cross on a large field of white — and that white meant exactly what you may suppose it did.“As a people, we are fighting to maintain the Heaven-ordained supremacy of the white man over the inferior or coloured race,” the Savannah Morning News wrote. “A white flag would thus be emblematical of our cause.”The problem was that it was impossible to keep that white flag clean.Jimmie Johnson should tell that story to his fans every time he gets the chance.There is no innocent thread in that flag: it was the battle standard of Robert E. Lee’s Virginia troops engaged in a malevolent racism that rent the country in two, the pennant of an old slave driver who chose to fight for plantation over country.Next time Denny Hamlin has a news conference, he should turn it over to a lively discussion of which side was really fighting a war of “aggression”. He should quote what men such as Jefferson Davis and Robert Barnwell Rhett really said about the expanding empire they envisioned, which included annexing tropical territories to extend slavery into Cuba, Jamaica, South America. Rhett boasted of building “a great Slaveholding Confederacy, stretching its arms over a territory larger than any power in Europe possesses”. There’s your so-called war of Northern aggression.Sentimental clinging to the Confederate flag by sports audiences has as much to do with fear as racism, I suspect. It has to do with a reluctance to face the potentially unbearable revelation. As W.E.B du Bois wrote in his classic 1935 work Reconstruction in America, so much of Civil War retellings are “cajoling and flattering the South and slurring the North”. The South must be flattered, and the North slurred, because otherwise what you are left with is the simple fact that some Americans made monstrously wrong, immoral choices. The easiest way to cover that up is to wave an old flag and say they were just nice Southern boys doing their duty for their home soil.To which Du Bois says: “This may be fine romance, but it is not science. It may be inspiring, but it is certainly not the truth. And beyond this it is dangerous. It is helping to range mankind in ranks of mutual hatred and contempt, at the summons of a cheap and false myth.”And it helped in 2020 to hang a noose in a black man’s garage.What if America isn’t what you thought it was? That’s the fear you face by pausing to read a little more deeply about that flag. What Nascar drivers can do, the invaluable service they can perform for their audience, is to explain that authentic American history is invariably better than the cheap and false myth. “Learning some history is the only way to know who we are, how we got here, where we might be going,” the author David Blight has said.The reader who braves the experience will be comforted, not distressed. All the magnificent and moving values you hoped for are embodied there — just maybe in different, more surprising, places.Places such as the account books of poet Henry Longfellow, who helped to finance the escapes of fugitive slaves. Or the graduation rolls of the Harvard class of 1861, 68 per cent of whom volunteered to fight for the Union, the best-educated young elites of the North, who with the first shot fired decided to forgo ease and suffered a 30 per cent combat casualty rate for it. Why don’t we talk more about their devotion to duty? Why don’t we replicate the flag of the 20th Massachusetts Regiment in souvenir shops?The courage and the crime of the Confederate battle flag are inseparable, as that noose proved. It was long past time that Nascar walked away from that tarted-up banner, and all of its old like-it-or-not racist associations, from the hand-glove partnership with George Wallace to the segregation of Darlington. If you think that walk was a small one, well, look at how long it took. It was a giant step.• Sally Jenkins is a sports columnist for The Washington Post. She began her second stint at the Post in 2000 after spending the previous decade working as a book author and as a magazine writer