Holocaust
The Holocaust, during which some 6 million Jews, Gypsies, homosexuals and other people were systematically exterminated by Nazi Germany during World War II, was one of the most horrific war crimes ever committed.
"Six million of our people live on in our hearts. We are their eyes that remember. We are their voice that cries out. The dreadful scenes flow from their dead eyes to our open ones. And those scenes will be remembered exactly as they happened. " - Shimon Peres