APOLOGY, restitution, and reconciliation are in the air these days. The pope has been to Israel and asked forgiveness for Christian anti-Semitism. German corporations are paying reparations to laborers enslaved in World War II-era factories. Officials of the old regimes in Eastern Europe have offered excuses for their actions under Communism. And South Africa's Truth and Reconciliation Commission has given amnesty to torturers and death-squad members who fully confess their crimes and repent.

But apologies and reconciliation can only happen when everyone admits that particular events actually happened. And from the current wave of truth-telling, one important piece of history has been missing.

If you were to ask most Americans or Europeans what were the great totalitarian systems of the century just ended, almost all would be likely to say: Communism and Fascism. But the violent 20th century was home not to two great totalitarian systems, but to three: Communism, Fascism, and European colonialism-the latter imposed in its deadliest form in Africa. Each of the three systems asserted the right to control its subjects' lives; each was buttressed by an elaborate ideology; each perverted language in an Orwellian way; and each caused tens of millions of deaths. In all three cases, we are still living with the consequences.

I learned something about the scale and deadliness of the third of these systems while writing a book about the single most murderous episode in the European seizure of Africa, the exploitation of the Congo by King Leopold II of Belgium. It was a part of history of which I had known almost nothing beforehand.

One day, I was reading a book on something else entirely, in which there was a reference to Mark Twain's participation in the worldwide movement protesting the atrocities in King Leopold's Congo-events that historians believed had taken many millions of Lives. I was startled. Why didn't I know anything about that? I had been writing about human-rights issues for years and, first as a student and then as a journalist, had been to Africa half a dozen times, once even to the Congo itself. I knew Europe's conquest of the continent had been bloody. But so many deaths in just one colony? I began to look into the subject.

Leopold got his hands on the huge territory of the Congo in the early 1880's. Amazing as it may seem, he convinced the United States and the major European countries to recognize it as his personal possession. (It only became the Belgian Congo, ruled by the Belgian government, in 1908.) In the 1890's, the invention of first the inflatable bicycle tire and then the automobile ignited a worldwide rubber boom; Leopold turned much of his colony's adult male population into slave laborers, forcing them to spend years gathering the Congo's abundant wild rubber.

The king's soldiers drove many of those workers to death, raped their wives, plundered their villages, and shot down tens of thousands who rebelled. Hundreds of thousands more Congolese fled the draconian regime, but the only place they were able to go was deep into the rain forest-where they died from lack of food and shelter.

Refugee flight, uprisings, and the conscription of most able-bodied men as forced laborers meant few of the Africans were able to cultivate crops and go hunting or fishing. Famine spread throughout the territory, and millions of traumatized, half starved people died of diseases that they otherwise would have survived. Joseph Conrad saw the beginnings of the frenzy of plunder and death and recorded it memorably in Heart of Darkness. Between 1880 and 1920, according to the best demographic estimates today, the population of the Congo was slashed in half: from roughly 20 million to 10 million people. (Some writers cite even higher numbers: In The Origins of Totalitarianism, Hannah Arendt used a figure of 12 million deaths.)

None of those events is news to any serious scholar of Central African history, and with the growth of African-studies programs in the last four or five decades, we have some good ones in American universities. As I began my research, I found many scholarly studies of different aspects of Leopold's rule in Africa. But I was baffled that-given the enormous death toll-no one had written a book on the Congo holocaust in English for a general audience in nearly a century.

Initially, it was hard to interest publishers in such a book: Of the 10 American houses shown the book proposal, only one responded with an offer. That was so despite the fact that two of my three previous books had been named "Notable Books of the Year" by The New York Times Book Review.

Since then, I've often wondered at the lack of interest by publishers. I think it has to do with the way we have thought of colonialism as being of a lesser order of evil than Communism and Fascism. Unconsciously, we feel closer to the victims of Stalin and Hitler, because they were mostly European. Consciously, we tell ourselves that Communism and Fascism are more worth writing about, or devoting college courses and research centers to, because they were full-fledged totalitarian ideologies that censored all dissent. Colonialism, on the other hand, seems something antiquated, redolent of sun helmets and "Dr. Livingstone, I presume?" We forget that tens of millions of Africans died as its victims. (For that matter, we forget that Henry Morton Stanley's most fateful impact on history was not finding Dr. Livingstone, but the five long years he spent staking out the borders of the Congo as a high-paid employee of King Leopold II.)

And yet, wasn't colonialism also totalitarian? Surely nothing is more so than a forced-labor system. And censorship was tight under colonial rule: For the first half of the 20th century, an African opposing such a regime had as little chance of access to the local press as a dissident in Hitler's Germany or Stalin's Russia.

Furthermore, colonialism was justified by an elaborate ideology that was embodied in everything from Kipling's poetry to sermons, politicians' speeches, and long books about racial theory and the superiority of European civilization. A key part of that ideological underpinning was much blather about how the colonizers were introducing lazy natives to the benefits of labor. "In dealing with a race composed of cannibals for thousands of years," King Leopold II told an American correspondent, "it is necessary to . . . make them realize the sanctity of work." From there, it's not such a big step to the words over the gate at Auschwitz, ARBEIT MACHT FREI.

European colonialism also involved the same perversion of language, the use of words to mean their opposite, that was embodied in that slogan and that we associate with Nazi and Soviet propaganda. In Leopold's forced-labor system, for instance, the workers were referred to as "liberes" or "liberated men." The irony was usually lost on the king's officers. One reported about the problem of lines of "liberated men" crossing narrow log bridges over jungle streams: When "liber6s chained by the neck cross a bridge, if one falls off, he pulls the whole file off and it disappears," the officer noted. Language like that reminds one of Orwell's Ministry of Truth in 1984.

DESPITE THE MISGIVINGS Of nine publishers, a 10th had faith in my project. My book, King Leopold's Ghost: a Story of Greed, Terror and Heroism in Colonial Africa, eventually reached bestseller lists in four countries. One was Belgium. It has been fascinating to watch the reaction there. Unlike, say, a book about the Holocaust that appears in Germany, this was a book about a holocaust of which most Belgians are totally unaware. How can you come to terms with a piece of history when you don't know that the history took place?

Although a tradition of good critical scholarship on the subject of European colonialism is now well established in Britain and France, none of the European countries have fully faced up to the bloodshed that their colonization brought to Africa. Germany, for example, has memorials to Jewish victims of Nazism, but seldom commemorates victims of an earlier genocide that was in some ways a dress rehearsal: the 1904-5 near-extermination of the Herero people of German Southwest Africa, today's Namibia.

Outside Brussels sits the Royal Museum of Central Africa, a vast chateau-like complex said to be the world's biggest museum of Africana. But the signs in its 20 large exhibition galleries say not one word about the millions of Congolese who died while the beautiful tools, masks, sculptures, and musical instruments displayed were being brought back to Europe. It is as if there were to be a huge museum of Jewish art and artifacts in Berlin-with no mention of the Holocaust.

I went to Belgium on my book tour. The journalists who interviewed me were mostly young, concerned about human rights-and uniformly apologetic that they had learned nothing in school about their country's bloody past in Africa. The newspaper reviews were positive. And then the reaction set in.

It came most vocally from some of the tens of thousands of Belgians who had had to leave Africa in a hurry; their world collapsed, when the Congo suddenly won its independence in 1960. Today there are more than two dozen organizations of Belgian old colonials, with names like the Fraternal Society of Former Cadets of the Center for Military Training of Europeans at Luluabourg. A coalition of those groups opened a World Wide Web site last year, containing a long, furious attack on my book: "sensationalist . . . an amalgam of facts, extrapolations and imaginary situations. . . ." and so on.

Jean Stengers, professor emeritus of history at the Free University of Brussels, president of the Belgian Historical Sciences Committee, and a politically powerful ally of the old colonials, joined the assault. He scorned the idea that there had been millions of victims of Leopold's misdeeds in the Congo: "If there is a victim at the hands of Monsieur Hochschild, it is Leopold II," he wrote in the Brussels newspaper Le Soir.

The controversy spread to another arena. An African student in Belgium posted a frantic message on the Internet with the heading, "Brothers, Help!" His name was Joseph Mbeka, and he was a graduate student in Brussels. When he had cited some facts from my book during the oral defense of his thesis, Mbeka reported, "my thesis chairman literally turned his back," declared the facts highly questionable-and flunked him. Mbeka urged people to write letters of protest to his institute.

The British newspaper The Guardian then published a lengthy article about how "a new book has ignited a furious row in a country coming to grips with its colonial legacy." The article quoted Stengers once again denouncing the book and saying, "In two or three years' time, it will be forgotten." The British reporter then cited an official of Belgium's Royal Museum of Central Africa saying that possible changes in its exhibits were under study, "but absolutely not because of the recent disreputable book by an American." The Guardian correspondent even questioned the Belgian prime minister, who evasively declared, "The colonial past is completely past. There is really no strong emotional link any more. . . . It's history."

WILLIAM FAULKNER, knowing the weight of history on the American South, knew better. He once said, "The past is not dead. It's not even past." Listening to angry Belgians was a reminder to me of how history, as remembered and mythologized informally, and as taught formally in colleges and universities, is far from being a clear set of facts and trends everyone agrees on. It is something whose every facet bears the imprint of political forces in the present.

I have found myself wondering why a controversy erupted so furiously in Belgium around a book on the holocaust in the Congo, while we Americans seem to be doing better in coming to terms with the worst stains on our own past-slavery and the genocide of Native Americans. Despite controversies over flying the Confederate battle flag in the South and museum exhibits on new interpretations of the history of the American West, dozens of excellent books on both slavery and the Native American genocide exist, along with published recordings of oral histories of former slaves. The National Museum of the American Indian is taking shape under the auspices of the Smithsonian Institution. The last few years have seen the PBS series Africans in America, and Hollywood films like Amistad and Beloved.

It wasn't always so. When I was in high school in the late 1950's, slavery was in our textbook mainly for its role in the Civil War; we learned next to nothing about the daily life of slaves. We learned about the "manifest destiny" debates, but little about how it felt to the Lakota or Apache who were the victims of that westward expansion. When I majored in American history and literature at college in the early 1960's, I was never assigned a single book written by a person of color. A visitor to Virginia's Colonial Williamsburg before 1970 would have seen no indication that roughly half the population of the real Williamsburg of several centuries ago had been slaves.

However, there was no equivalent in Europe to the American civil-rights movement and all it gave rise to. The reason was that Europe, unlike the United States, did not have some 30 million people of African descent living within its borders. The descendants of the Africans who were victims of European enslavement were not in Europe itself, but still in Africa. And, despite a trickle of African immigration to Europe, that is still true today.

Which voices from the past we listen to-both in the academic history of textbooks and the public history of monuments and museums-is something determined not only by the historians, but by the voices of all the people who shape the cultural climate in which historians and museum directors live and work. And with African voices still mostly unheard in Europe, colonial history remains largely swept under the rug.

Don't expect public apologies any time soon.