Disunion follows the Civil War as it unfolded.

Henrik Drescher

Walpole, N.H.

More than once during the Civil War, newspapers reported a strange phenomenon. From only a few miles away, a battle sometimes made no sound — despite the flash and smoke of cannon and the fact that more distant observers could hear it clearly.

These eerie silences were called “acoustic shadows.”

Tuesday, the 150th anniversary of the first engagement of the Civil War, the Confederacy’s attack on Fort Sumter, we ask again whether in our supposedly post-racial, globalized, 21st-century world those now seemingly distant battles of the mid-19th century still have any relevance. But it is clear that the further we get from those four horrible years in our national existence — when, paradoxically, in order to become one we tore ourselves in two — the more central and defining that war becomes.

In our less civil society of this moment we are reminded of the full consequences of our failure to compromise in that moment.

In our smug insistence that race is no longer a factor in our society, we are continually brought up short by the old code words and disguised prejudice of a tribalism beneath the thin surface of our “civilized” selves.

And in our dialectically preoccupied media culture, where everything is pigeonholed into categories — red state/blue state, black/white, North/South, young/old, gay/straight — we are confronted again with more nuanced realities and the complicated leadership of that hero of all American heroes, Abraham Lincoln. He was at once an infuriatingly pragmatic politician, tardy on the issue of slavery, and at the same time a transcendent figure — poetic, resonant, appealing to better angels we 21st-century Americans still find painfully hard to invoke.

The acoustic shadows of the Civil War remind us that the more it recedes, the more important it becomes. Its lessons are as fresh today as they were for those young men who were simply trying to survive its daily horrors.

And horrors there were: 620,000 Americans, more than 2 percent of our population, died of gunshot and disease, starvation and massacre in places like Shiloh and Antietam and Cold Harbor, Fort Pillow and Fort Wagner and Palmito Ranch, Andersonville and Chickamauga and Ford’s Theater.

Yet in the years immediately after the South’s surrender at Appomattox we conspired to cloak the Civil War in bloodless, gallant myth, obscuring its causes and its great ennobling outcome — the survival of the union and the freeing of four million Americans and their descendants from bondage. We struggled, in our addiction to the idea of American exceptionalism, to rewrite our history to emphasize the gallantry of the war’s top-down heroes, while ignoring the equally important bottom-up stories of privates and slaves. We changed the irredeemable, as the historian David Blight argues, into positive, inspiring stories.

The result has been to blur the reality that slavery was at the heart of the matter, ignore the baser realities of the brutal fighting, romanticize our own home-grown terrorist organization, the Ku Klux Klan, and distort the consequences of the Civil War that still intrude on our national life.

The centennial of the Civil War in 1961 was for many of us a wholly unsatisfying experience. It preferred, as the nation reluctantly embraced a new, long-deferred civil rights movement, to excavate only the dry dates and facts and events of that past; we were drawn back then, it seemed, more to regiments and battle flags, Minié balls and Gatling guns, sentimentality and nostalgia and mythology, than to anything that suggested the harsh realities of the real war.

Subsequently, our hunger for something more substantial materialized in James McPherson’s remarkable “Battle Cry of Freedom” and many other superb histories, in the popular Hollywood movie “Glory,” and in my brother Ric’s and my 1990 documentary series “The Civil War.”

It was an emotional archaeology we were all after, less concerned with troop movements than with trying to represent the full fury of that war; we were attracted to its psychological disturbances and conflicted personalities, its persistent dissonance as well as its inspirational moments. We wanted to tell a more accurate story of African-Americans, not as the passive bystanders of conventional wisdom, but as active soldiers in an intensely personal drama of self-liberation.

We wished to tell bottom-up stories of so-called ordinary soldiers, North as well as South, to note women’s changing roles, to understand the Radical Republicans in Congress, to revel in the inconvenient truths of nearly every aspect of the Civil War.

Today, the war’s centrality in American history seems both assured and tenuous. Each generation, the social critic Lewis Mumford once said, re-examines and re-interprets that part of the past that gives the present new meanings and new possibilities. That also means that for a time an event, any event, even one as perpetually important as the Civil War, can face the specter being out of historical fashion.

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But in the end, it seems that the War of the Rebellion, the formal name our government once gave to the struggle, always invades our consciousness like the childhood traumatic event it was — and still is.

Maybe Walt Whitman, the poet and sometime journalist who had worked as a nurse in the appalling Union hospitals, understood and saw it best. “Future years,” he said, “will never know the seething hell, the black infernal background of the countless minor scenes and interiors … of the Secession War, and it is best they should not.

“The real war,” Whitman admonished us, “will never get in the books.” We are, nonetheless, obligated to try.

Ken Burns is the director of the documentary series “The Civil War” and the forthcoming “Prohibition.”

A version of this Op-Ed appeared in print on April 12, 2011.