Observing the centennial anniversary of the Civil War in the early 1960s was a national fixation, but a central element of the story, slavery, and the role of blacks as soldiers was minimized in many observances.

July 1 marked the 150th anniversary of the second day of the war’s greatest battle, at Gettysburg, and despite the crowds gathered at the battlefield in Pennsylvania and the space devoted to the subject on the front page, the war’s sesquicentennial is far from the forefront of popular thinking.

Maybe we’ll get it right for the 200th anniversary.

The Civil War raged from 1861 to 1865, and there is little question that it remains the most important event in American history, ending the unconscionable practice of slavery and redefining a collection of 50 states as a single nation.

But the incompleteness of this transformational event was exposed when the centennial came around, as historian David Blight illustrated in his 2011 “American Oracle: The Civil War in the Civil Rights Era.”

It was a time, Blight observed, when Martin Luther King Jr. would stand on the steps of the Lincoln Memorial and proclaim, “One hundred years later, the Negro still is not free” while the Virginia Civil War Commission would declare just as firmly, if less memorably, that “the Centennial is no time for finding fault or placing blame or fighting the issues all over again.”

By and large, the Virginia commission’s point of view prevailed in observances of the Civil War’s 100th anniversary, which was framed as a valiant two-way clash: Blue vs. Gray, brother vs. brother something not just to memorialize, but in a sense, to celebrate.

“For the majority, especially of white Americans,” Blight wrote, “even as they watched TV images of civil rights marchers being clubbed by police and bitten by dogs in Birmingham, Alabama, to claim the centrality of slavery and emancipation in Civil War memory was still an awkward kind of impoliteness at best and heresy at worst.”

Today that has changed. When filmmaker Ken Burns presented the history of the war in his acclaimed 1990 series, he put slavery at the heart of the story. In his new popular history, “Gettysburg: The Last Invasion,” historian Allen Guelzo writes not just of the white soldiers engaged a cataclysmic threeday battle, but of free blacks living in and around Gettysburg who, if they were unfortunate enough to encounter rebel troops, were swept back into slavery.

But if the prevailing view of the war is now more nuanced and accurate, and the event no less important in history, how to explain what can only be described as a relative lack of interest as we pass through another significant anniversary?

Surely the passage of time itself is an important factor. The pre-eminent popular historian of the centennial era, Bruce Catton, was drawn to the subject by childhood memories of Civil War veterans marching in memorial parades. War weariness may also be a factor.

But we suspect a continued uneasiness with racial relations, past and present, is at work, too.

David Herbert Donald, a Mississippian who became a Harvard professor and Lincoln scholar, was once asked if he thought the country had come to terms with its prejudices. Donald’s answer was that he suspected we had become better at hiding them.

— Concord (N.H.) Monitor