Not so long ago, the Civil War was taken to be this country’s central moral drama. Now we think that the aftermath—the confrontation not of blue and gray but of white and black, and the reimposition of apartheid through terror—is what has left the deepest mark on American history. Instead of arguing about whether the war could have turned out any other way, we argue about whether the postwar could have turned out any other way. Was there ever a fighting chance for full black citizenship, equality before the law, agrarian reform? Or did the combination of hostility and indifference among white Americans make the disaster inevitable?

Henry Louis Gates, Jr., in his new book, “Stony the Road: Reconstruction, White Supremacy, and the Rise of Jim Crow” (Penguin Press), rightly believes that this argument has special currency in the post-Obama, or mid-Trump, era. He compares the rosy confidence, in 2008, that the essential stain of American racism would fade through the elevation of a black President with the same kind of short-lived hopes found in 1865, when all the suffering of the war seemed sure to end with civil equality. Instead, the appearance of African-American empowerment seemed only to deepen the rage of a white majority. Then it brought forward Klan terrorism and Jim Crow in the South; now it has brought to power the most overtly racist President since Woodrow Wilson, openly catering to a white revanchist base. It’s a depressing prospect, and Gates is properly depressed and depressing about it.

The broad outlines of the Reconstruction story have long been familiar, though the particular interpretive pressures put on particular moments have changed with every era. Toward the end of the war, Washington politicians debated what to do with the millions of newly freed black slaves. Lincoln, after foolishly toying with recolonization schemes, had settled on black suffrage, at least for black soldiers who had fought in the war. (It was a speech of Lincoln’s to this effect that sealed his assassination: John Wilkes Booth, hearing it, said, “That means nigger citizenship. Now, by God, I’ll put him through.”)

After Lincoln’s death, his hapless and ill-chosen Vice-President, Andrew Johnson, did as much as he could to slow the process of black emancipation in the South, while the “radical” core of the abolitionist Republicans in Congress tried to advance it, and, for a while, succeeded. Long dismissed as destructive fanatics, they now seem to be voices of simple human decency. Thaddeus Stevens, the abolitionist congressman from Pennsylvania, proposed shortly after the war’s end, in his “Lancaster” speech, a simple policy: punish the rebel leaders; treat the secessionist states as territories to be supervised by Congress, thus protecting the new black citizens; take the confiscated plantations on which masters had worked slaves like animals, and break up those plantations into forty-acre lots for the ex-slaves to own (a form of the classic “forty acres and a mule”). That this minimally equitable plan was long regarded as “radical” says something about how bent toward injustice the conversation quickly became.

Freed slaves eagerly participated in the first elections after the war, and distinguished black leaders went to Congress. The 1872 lithograph of “The First Colored Senator and Representatives,” by Currier & Ives, no less, shows seven black men given the full weight of mid-century Seriousness, including the first black senator from Mississippi, Hiram Rhodes Revels.

But white state governments steadily reconstituted themselves. By the eighteen-nineties, they were passing laws that, piece by piece, reclaimed the right to vote for whites alone. All of this was made worse by one of those essentially theological “constitutional” points which American professors and politicians love to belabor. Lincoln’s argument was always that, since it was unconstitutional for states to secede on their own, the rebel states had never seceded. The rebels were not an enemy nation; they were just a mob with a flag waiting to be policed, and the Union Army was the policeman. The idea was to limit any well-meaning attempt at negotiation, and to discourage foreign powers from treating the Confederacy as a separate state. After the war, though, this same idea implied that, since the state governments had never gone out of existence, their reborn legislatures could instantly reclaim all the rights enjoyed by states, including deciding who could vote and when.

As Stevens pointed out, the reasoning that says that no states seceded because the Constitution won’t allow it would also say that no man can ever commit murder because the law forbids it. “Black Codes” were put in place in most Southern states that, through various means, some overt and some insidious (anti-vagrancy statutes were a particular favorite), limited the rights of blacks to work and to relocate. The legislative reconquest was backed by violence: the Ku Klux Klan, formed as a terrorist organization by ex-Confederate officers, began murdering and maiming assertive black citizens. In 1877, after a mere dozen years in which black suffrage and racial equality were at least grudgingly accepted national principles, the federal government pulled its last troops from the South and, in what could be called the Great Betrayal, an order of racial subjugation was restored.

It’s a story with fewer pivotal three-day battles than the war fought over slavery, but its general shape is oddly similar: after a stunning series of victories and advances in the early years by the “rebels”—in this case, egalitarian forces—the armies of Reconstruction began to fall victim to the sheer numbers of the opposing side and to the exhaustion of their allies and reserves. Some battles, both real and rhetorical, do stand out. There were the arguments in Congress, pitting newly minted and almost impossibly eloquent black representatives against ex-Confederate politicians who a few years earlier had been sending hundreds of thousands of young men to their death in order to preserve the right to keep their new colleagues in perpetual servitude. There was the so-called Battle of Liberty Place, in New Orleans in 1874, a riot on behalf of the White League, a gang of ex-Confederate soldiers who sought to oust Louisiana’s Republican governor and its black lieutenant governor. In a moment of extraordinary moral courage, as worthy of a film as any Civil War battle, James Longstreet, the most capable of General Lee’s Confederate lieutenants, agreed to lead municipal police, including black officers, to put down the white riot and restore the elected government. He knew what it would cost him in status throughout the old Confederacy, but he did it anyway, because it was the right thing to do. Naturally, the city’s monument to the attempted coup bore an inscription that conveyed the White League’s point of view, and, sobering fact, it was scarcely two years ago that the racist memorial to the riot finally came down—with a police escort to protect the movers.

Gates emphasizes that Reconstruction was destroyed not by white terrorism alone but also by a fiendishly complicated series of ever more enervating legal and practical assaults. The Supreme Court played a crucial role in enabling the oppression of newly freed blacks, while pretending merely to be protecting the constitutional guarantee of states’ rights—one more instance in which “calling balls and strikes” means refusing to see the chains on the feet of the batter. The overtly racist decision in Plessy v. Ferguson (1896) arrived long after the worst was already done, but it sealed the earlier discrimination in place, and Jim Crow thrived for another half century. Meanwhile, at least some of those Northern liberal abolitionists—including the likes of Henry Adams and the well-meaning Horace Greeley—managed, in the way of high-minded reformers, to let their pieties get the better of their priorities: recoiling against the apparent improprieties of the pro-suffrage Grant Administration, they made common cause with the Democrats who were ending democracy in the South. “When, therefore, the conscience of the United States attacked corruption,” W. E. B. Du Bois wrote in his classic 1935 study, “Black Reconstruction in America,” in many ways the most astute account of the period ever produced, “it at the same time attacked in the Republican Party the only power that could support democracy in the South. It was a paradox too tragic to explain.”