This year marks the 150th anniversary of Gen. Lee's surrender to Gen. Grant at Appomattox. In some places, including Grant's Tomb in New York City, the anniversary observances on April 9 included a ceremony featuring the symbolic furling of the Confederate battle flag. So it is surreal that this year would also mark the furling of the Confederate flag on the grounds of the remaining state capitals where it still flies.

No less surreal is that the impetus for this development came from Charleston, S.C., once the hotbed of secession. As the columnist Charles Krauthammer writes, a major impetus for this development was a desire to reciprocate the powerful example of Christian charity and forgiveness set by the nine Emanuel Methodist Episcopal Church murder victims' families.

This invites yet another analogy to 1865: Grant's magnanimity toward Lee and his troops was critical to ensuring the United States would be one nation again.

South Carolina's vote to lower the flag at Gov. Nikki Haley's call is correct and long overdue. The Confederacy sought to overthrow our constitutional government. When the Confederates fired on Fort Sumter in Charleston Harbor, they were not merely firing at "Federals" or the Union army. They were firing at the United States Army and the U.S. flag.

Moreover, the evidence is overwhelming that the longterm preservation of slavery was the primary motivation for secession. It was a direct reaction to the election, for the first time in the nation's history, of a Republican administration that opposed expansion of slavery into the territories.

The national debate leading up to the war focused on slavery, as did last-minute attempts to avert war in 1861. Slavery permeates Lincoln's first inaugural address and also the official declarations of five of the seceding states explaining their secession from the Union. Four were phrased in terms of the interests of "slaveholding states." The fifth, Mississippi, called slavery "the greatest material interest of the world."

Mississippi's resigning senator, soon to be Confederate President Jefferson Davis, lamented his state "has heard proclaimed the theory that all men are created free and equal, and this made the basis of an attack upon her social institutions; and the sacred Declaration of Independence has been invoked to maintain the position of the equality of the races." Confederate Vice President Alexander Stephens asserted the Confederate government's "cornerstone rests upon the great truth that the negro is not equal to the white man; that slavery ... is his natural condition."

Less than two years later, the Emancipation Proclamation made the abolition of slavery in areas of rebellion the explicit cause of the Union. "All knew" slavery "was somehow the cause of the war," Lincoln declared in his second inaugural address before surmising that God may have given "both North and South this terrible war as the woe due to those by whom the offense [of slavery] came."

The role of slavery was later obfuscated by a broad cultural and literary movement sometimes known as the Myth of the Lost Cause. This sought to glorify the Confederacy, which meant downplaying slavery even as the former Confederacy fought civil rights measures during Reconstruction.

As the magnanimous hero of Appomattox, former President Grant could speak with authority about reconciliation, but he warned after Reconstruction that the "spirit of conciliation" with the South should not go as far as to "surrender the results of the war. I am afraid there is a large party in the North who would do that now." Indeed, that is precisely what happened. The Northern passion for reconciliation went so far that it enabled a new era of Jim Crow segregation and disfranchisement.

That was the predicate for the emergence of the official use of the Confederate flag. It began with Mississippi's incorporation of the battle flag into its state flag in 1894, but mostly it came much later, in reaction to the Civil Rights movement. There was little mystery as to the flag's relevance to an anti-civil rights platform.

It took a generation for the flag's official government display to prompt a national debate during the 1990s, just as historians began widely questioning the century-old historical revisionism. By then, the Myth of the Lost Cause had shaped history lessons for nearly every living American, enabling and even encouraging people devoid of racism to defend the flag.

In the world of Civil War preservation and commemoration, I know scores of people active in Confederate heritage groups without a racist bone in their bodies. I do not question their sincerity when they defend the flag with the "heritage not hate" mantra. Many even supported the recent restoration of Grant's Tomb.

And there is a place to commemorate the valor of those who died in service to an unworthy cause. But the flag that fired on the American flag should not fly as an active government symbol — which, after all, connotes our shared identity. For all the racial tensions that remain in the news, the Charleston tragedy was the exception that proved the rule of how much consensus we have achieved on race by any historical perspective.

The good news is that today, we are all emancipationists. We even embrace the once controversial Radical Republican view of racial equality before the law. The bad news is that truthful history was a casualty on the path to national unity. Who would have predicted the role of Christian forgiveness, 150 years after Appomattox, in helping to change that?

Frank Scaturro, a partner at FisherBroyles LLP, is president of the Grant Monument Association and author of President Grant Reconsidered. Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.