This article was originally published in Newsweek and may be accessed here.

When General Ulysses S. Grant received General Robert E. Lee at Appomattox to arrange the surrender of his Army, Grant recalled their service together in the Mexican War, when Grant was a young officer. Grant was able to summon his sympathy for "the downfall of a foe who had fought so long and valiantly," but he was quick to add: "though the cause was, I believe, one of the worst for which a people ever fought, and one for which there was the least excuse."

Grant could have sympathy for an accomplished soldier, but Lee had devoted his arts and valor to a deeply wrongful end, and that sense of things was bound up with the moral meaning of "treason." To take up arms in a secession was to take up arms in overthrowing the results of a free election—the 1860 election that brought Abraham Lincoln to office. To seek to overthrow a free election through violence was nothing less, as Lincoln said, than denying the right of a people to govern itself; it was a denial of government by "the consent of the governed." As Lincoln also understood, slavery marked the radical denial of the right of a human being to govern himself. And so it was no accident that the refusal to be bound by the consent of the people in a free election came from the same people who would make slaves of other men.

To be in a state of treason to America meant precisely to deny the moral ground on which the American people came together politically under the "consent of the governed." This was strikingly different from the men who sought to be traitors to Hitler's government and reject the principles of the Nazi regime. These, by contrast, are "traitors" we rightfully honor. Lincoln had no hesitation in branding Robert E. Lee as a "traitor," even as he was magnanimous, in victory, to those who had fought and suffered on the other side. But nothing in that magnanimity was taken to deny or erase the moral wrong of seeking to destroy a free government and preserve slavery.

We did not hear from Lincoln or Grant a willingness to sweep away that moral judgment on the grounds that Confederate soldiers were "willing to die for their beliefs." That notion would treat, on the same moral plane, the deaths of soldiers on both sides, as though the moral ends for which the war was fought made no difference for the justification for the war and the lives that were lost. This sense of things flared up remarkably in the mid-1980s, when President Ronald Reagan sought to lay wreaths at the cemetery in Bitburg, Germany that contained fallen members of the Nazi SS. The willingness of these men to die for their beliefs did not erase, for Americans, the wrongness of their cause.

But that stand made sense only because Lincoln and Grant took seriously the "truth" of the Declaration of Independence: that no man was by nature the ruler of other men in the way that God was by nature the ruler of men, and men were by nature the ruler of dogs and horses. And where would that be true? Everywhere in the world where that nature remained the same, and men were still distinguishable from animals. Hence the notion of "natural rights," rights grounded in an enduring nature. And Lincoln's conviction that this truth, as articulated by Jefferson, "was applicable to all men and all times."

The notion of crediting people solely because they "died for their beliefs" is a line that took hold as the conviction began seriously to erode that there were indeed truths of that kind, holding in all places and times. Toward the end of the 19th century, that doctrine was tellingly displaced on behalf of the school of "historicism" brought from the Historical School in Germany: that truths can be known only in the historical epoch in which they are held. Except, of course, for the truth of "historicism": that doctrine will apparently hold true in all ages.

Years ago, in Princeton, I encountered a graduate student in history, and when she told me hat her specialty was the 19th century, I told her that we were already at odds: For I did credit Lincoln's line that the "truth" of the Declaration was indeed a truth "applicable to all men and all times." To which she said, "He thought it was true at the time." Justice Oliver Wendell Holmes, who had fought in the Civil War, lost his faith in those truths, and became one of the most vulgar historicists of his age. He too would commend people who were willing to fight, as he did, without conviction, and "give all for belief."

In his collection of moving letters written home by the Civil War soldiers on both sides (What They Fought For), James McPherson again fell into the mold of commending both sides because they were willing to "die for their beliefs." The understanding of soldiers, of course, would vary widely, but it was striking as to how many soldiers, in their letters, were picking up Lincoln's lines. One Irish soldier explained to his parents back in Ireland that, "This is my country as much as the man who was born on the soil. ...This is the first test of a modern free government in the act of sustaining itself against internal enem[ie]s."

In his large liberal gesture, McPherson was willing to put aside the moral differences that separated the two camps. But in doing that, he began by making light of that genuine "truth" that explained the motives of so many of those Union soldiers. He began, that is, by disrespecting their own account of why they were fighting. And in that respect, he did not really give a faithful account of What They Fought For.