AP Photo

Since the end of World War II the world has been rife with bloody conflicts in which, or after which, entire population groups have been murdered. One could cite the slaughter of millions by the Khmer Rouge in Cambodia, or the horrific tribal war in Rwanda, or the brutality in the former Yugoslavia, or the devastation in southern Sudan. But despite all this, the United Nations decided to devote a special memorial day only to the Holocaust of the Jews in Europe.

How was the Jewish Holocaust unique? Not only due to its scope and cruelty, but also due to the complete lack of the circumstances that caused other massacres. The Jews were not exterminated to enable the Nazis to take over their territory, because the Jews had no territory. They were not...