Rupert Cornwell: After 150 years, the Civil War still divides the United States

Out of America: As the country prepares to commemorate the great schism, the echoes of the bloody conflict still reverberate through its politics and culture

"A joyous night of music, dancing, food and drink" is probably not how most people would choose to mark an event setting the stage for a conflict that lasted four years, cost 620,000 lives, and ended in annihilating defeat.

But when it comes to the American Civil War, South Carolina is not ordinary. It was the state where passions ran highest then, and where the flame of the "Lost Cause" is most tenderly nourished now. The war was made inevitable by an act of defiance by South Carolina. How fitting, indeed how inevitable, that the 150th anniversary commemorations of the most traumatic and divisive event in the country's history should begin in similar vein, in the same state, tomorrow.

Whatever else the "Secession Ball" (tickets $100 apiece) at the handsome Gaillard Auditorium in downtown Charleston will be a colourful occasion. The programme kicks off with a 45-minute play re-enacting the signature of the Ordinance of Secession on 20 December 1860, by 170 delegates to a special convention set up by the South Carolina legislature as soon as news arrived of Abraham Lincoln's election victory on 6 November that year.

Then the party gets going in earnest. The guests, sipping champagne and mint juleps, will mostly be dressed in period clothes. The band will play "Dixie". The gentlemen will bow and the ladies curtsy as they step forward for the Virginia Reel, just like Vivien Leigh and Clark Gable in Gone with the Wind.

And perhaps the mood really was as festive, on that fateful evening a century and a half ago, with little suspicion of the bloodletting and savagery ahead that would destroy the Old South and its way of life for ever.

Within six weeks, the four other Deep South states, as well as Florida and Texas, had followed South Carolina out of the Union. Within three and a half months, Confederate guns had fired the first shots of the Civil War on the federal garrison at Fort Sumter in Charleston harbour.

What Lincoln called the "Mighty Scourge" was under way. The conflict would not end until 9 April 1865, with Robert E Lee's surrender at Appomattox court house in rural Virginia. In many respects the Civil War was the first war of the industrial era, fought with mass-produced weapons, whose battles prefigured the mass slaughter of the First World War just 50 years later.

It was also a war that aroused extraordinary passions. The fighting was mostly done by volunteers; yet by the time it was finally done, more than three and a half million Americans had been under arms – at a time when the total population was only 31 million (including more than three million slaves), a tenth of the figure today. The Civil War took as many lives as all America's other wars combined – from Lexington and Concord in 1775 against the British redcoats, to present-day Iraq and Afghanistan. And even now those passions have not subsided.

Mark Twain's observation in the South – "The war is what AD is like elsewhere; they date from it" – is an exaggeration. But it contains a kernel of truth. Argument still persists over what the Civil War was about. In the South's collective folk memory – nurtured by organisations such as the Sons of Confederate Veterans, which is sponsoring the Secession Ball – it was a struggle for "states' rights"; a war of self-defence against a domineering North, a gallant struggle in which the agrarian Athens of Dixie was ultimately defeated by a brutal Roman North, but only because of the latter's overwhelming advantages in population, industry and weapons.

To which, of course, most neutral historians, as well as every African-American, would respond that the Confederacy was fighting for just one single right: that of enslaving its fellow men. That is why America's most venerable civil rights group plans a peaceful protest march against the ball. "We are not opposed to observances," Lonnie Randolph, the head of the National Association for the Advancement of Colored People in South Carolina, said. "But we are opposed to disrespect, and this is nothing more than a celebration of slavery. I can only imagine what kind of celebration they would have if they [the South] had won."

In some ways, the South did win. Between now and 2015, America will be swamped with anniversaries, of great events, great battles, great tragedies, and, naturally, great speeches. Who would give odds against President Obama (or his victorious 2012 opponent) travelling to Gettysburg on 19 November 2013, to the spot where Lincoln gave his peerless address 150 years before?

Whether these commemorations can shift the balance of sentiment, however, and dispel the bogus aura of nobility that still envelopes the Old South, is quite another matter. Yes, there's long been a "New South", epitomised by the gleaming skyscrapers of Atlanta, Georgia, the emergence of a thriving black middle class, and sprawling suburbs and malls that could be Anywhere USA.

But the South remains the most distinctive part of America. It feels different, vaguely exotic in its rhythms, its vegetation, and the accents of its inhabitants. Although it lost the Civil War, it is perhaps the most patriotic region of an intensely patriotic country, with the strongest military tradition.

In relation to the Civil War, the vanquished South – and, above all, its military commanders – not the victorious North, has imprinted itself on the collective memory. Grant and Sherman come across as ruthless bullies compared with the impossibly distinguished Lee, model for the gentleman-soldier throughout the ages, or the gifted Thomas "Stonewall" Jackson, whose feats of generalship hover between truth and legend.

Lincoln was probably America's greatest president of all; but who does not harbour a strange fascination for the Confederacy's Jefferson Davis, whose limitations as commander-in-chief and head of government are for ever shrouded by the myth of the doomed leader of "the Lost Cause"?

Sentimentality is a potent distorter of memory. Think of the South and you think of magnolias and oaks laden with Spanish moss, and colonnaded antebellum mansions with lawns stretching down to languid rivers. You forget the abomination of slavery and the attendant cruelty on which this dream world was built.

In fact, the South Carolina secession document, whose original will be a star attraction at tomorrow's festivities in Charleston, is pretty explicit on the point. With Lincoln as president, it states, "the Slaveholding States will no longer have the power of self-government, or self-protection, and the Federal Government will have become their enemy".

In its own decision to secede, the state of Mississippi was yet more explicit. Slavery was "the greatest material interest of the world", it insisted; attempts to abolish it would undermine "commerce and civilization".

For African-Americans, by contrast, the Confederacy was, and remains, merely a symbol of racial oppression. If the Civil War was a victory for freedom, that freedom would be a long time coming. For that reason, at least, and despite the eternal argument over what brought the conflict about, this 150th anniversary should run rather more smoothly than the 100-year commemorations during the Kennedy and Johnson presidencies.

Those were the years of the civil rights struggle, which made a mockery of what the war and Lincoln's Emancipation Proclamation, issued in January 1863 when the outcome of the war was still far from certain, were supposed to have achieved. In the South, Jim Crow still ruled, segregation was everywhere, and voting laws were shockingly discriminatory; 100 years on, Martin Luther King was, in effect, fighting a second Civil War by peaceful means.

The centenary commemoration was little short of a fiasco, even though Congress had set up an official commission to oversee proceedings. That body, however, lost all credibility when it announced plans to meet in a segregated hotel. This time organisers have avoided any such initiative.

Now, in one sense, African-Americans have scaled the ultimate summit. One of theirs, who learnt his politics in Lincoln's state of Illinois, now sits in the Oval Office, having carried three of the 11 states of the old Confederacy. Barack Obama may have come to his office via Kenya, Hawaii and Indonesia, not Little Rock or Selma – but his wife is the great-great-granddaughter of slaves from the port of Georgetown in South Carolina's Low Country, a mere 50-odd miles from Charleston and tomorrow's Secession Ball.

In the South, the words of William Faulkner, one of its greatest literary sons, still ring true: "The past isn't dead. It isn't even past." Reminders come with the regular political set-tos over the use of Confederate symbols, such as flags on public buildings and the number plates of cars, by South Carolina and other Southern states.

Last spring saw national controversy when the governor of Virginia (the home state of Lee and Jackson) omitted any reference to slavery in a proclamation meant to focus attention on the Civil War's approaching anniversary. Every now and then, there are news stories about a resurgence of the Ku Klux Klan, in reality just one of many right-wing hate groups.

Then there is the enduring fondness of the South for the death penalty, especially for African-Americans. Three-quarters of all executions in the US take place in the former Confederate states, a direct legacy of lynching and of slavery before that, when capital crimes were far more numerous for blacks than whites.

Most striking of all, perhaps, is the continuing debate over states' rights – the division of power between the centre and the 50 states. Then it was about slavery. But only last week the argument raised its head again, when a judge in Virginia ruled that with its requirement that every citizen purchase insurance coverage, Obama's new healthcare plan overstepped the power of central government. States' rights, too, are implicit in the platform of the Tea Party movement, with its hostility to "big government" from Washington.

But Faulkner's dictum has its limits. Pace the recent musings of Rick Perry, the arch-conservative governor of Texas, that the secession of a state today, let alone another Civil War, is inconceivable. Let the adherents of the Lost Cause gaze long and lovingly on that document of 20 December 1860. They will never see its like again.