There was a photograph: a weeping Sudanese woman, standing before a freshly dug grave. There were statistics: 400,000 people dead, 2.5 million driven from their homes, "untold thousands" raped. There was an appeal: "Innocent civilians are being slaughtered in Darfur. You can end it," and a Web address, www.dayfordarfur.org.

This advertisement — which appeared on a full page of the International Herald Tribune last week — was truly arresting. But what really made me look twice was the slogan across the top: "When all the bodies have been buried in Darfur, how will history judge us?"

"How will history judge us?" Like much of the grassroots campaign that has sprung up to oppose the genocide in Darfur, this slogan is intended to evoke the genocides of the recent past. Earlier this fall 120 survivors of the horrors of the Holocaust, Cambodia, Rwanda and Bosnia signed an open letter calling for a U.N. peacekeeping force in Sudan. The stunning variety of organizations that have joined the Darfur campaign — they range from Amnesty International to the World Evangelical Alliance to the U.S. Holocaust Memorial Museum — also speaks to the evocative nature of the conflict.

And their call upon the witness of history has made an impact. Indeed, it is fair to say that were it not for the Christian, Jewish, human rights, genocide-prevention groups and others that have been talking about Sudan with such dedication, the massacres of Darfur might not be on the international agenda. The ads and rallies got "people in the street talking about something that happens far away," as an activist at Global Day for Darfur told me. Public interest has forced politicians to act.

The result: The United Nations is trying to form a multilateral peacekeeping brigade in Darfur, and the White House and Tony Blair are involved, too. And yet — it is not simple to explain why this particular grassroots action has been so successful. After all, Darfur is not the only place in the world where there has been mass murder, even ethnic mass murder, on a large, historically familiar scale. The North Korean regime has for years run concentration camps, directly modeled on the camps of Joseph Stalin's Soviet Union. But though there is excellent documentation of Pyongyang's camps — the U.S. Committee for Human Rights in North Korea even has satellite photographs on its Web site — and though some religious and university groups have made an effort, the level of interest, and therefore perhaps of U.N. involvement, is much lower.

The same is true of arbitrary arrests in Iran, some of which have also targeted particular ethnic groups for intimidation or elimination. For that matter, Saddam Hussein's use of chemical weapons to murder tens of thousands of Kurds never caught the popular imagination, not before the war and not afterward.

I can offer no scientific explanation as to why the tragedy of Darfur conjures up the specter of history's judgment and why other tragedies do not. But the answer must lie in the fact that this conflict has so few strategic or geopolitical implications. Because it seems to be in no one's "interest" to do so, a call for U.N. intervention in Darfur surely feels — at least to Americans and Europeans who haven't followed China's involvement in Sudan's oil industry — like an act of real charity, and not more evidence of the West pursuing its interests.

Equally important is the fact that Sudan plays no real role in Western domestic politics. Any discussion of North Korea will still evoke the Cold War, any conversation about Iran must touch on radical Islam. By contrast, when most of us look at Sudan, all we see is what Jan Egeland, the U.N. humanitarian coordinator, last weekend called "acts of inexplicable terror."

Taking a stand against genocide in Sudan does not require anyone to take a parallel stand on communism, the war on terrorism or the war in Iraq. It does not imply that you are left-wing, right-wing, pro- or anti-Bush. Once the U.N. is there, this may change: The U.S. intervention in Somalia immediately politicized what had also appeared to be an apolitical conflict. But at the moment, it is still possible to think of Darfur as an appropriate target for neutral humanitarianism.

None of this, I should emphasize, is meant to disparage the work of the extraordinary Darfur coalition, which has pushed an obscure and terrible war into the international spotlight. Nor do I mean to deny that "history will judge us," for surely it will. But when future generations look back on this era, they will judge us not only for how we responded to the most primitive and the most apolitical of horrors. They will also judge us by the consistency with which Western and international institutions battled sophisticated totalitarianism in all its forms: That is, they will judge us by the U.N.'s application of its own declarations on human rights, by America's ability to live up to the rhetoric of its leaders, by Europe's willingness to stand behind its stated values.

The creation of an international coalition to end genocide is an achievement, but its goals are still not deep or broad enough.

Anne Applebaum is a columnist for the Washington Post.