Holocaust was also known as the Shoah that happened between 1941 - 1945. Back during the World War II Hitler's troops killed some six million European Jews who lived in the Nazi occupied Germany and German concentration camps.
The Holocaust was a genocide done by Hitler and his troops. Thus taught us we have responsibilities to prevent such kind of genocides in the future and present.
Whatever it is, what mistake people would have done, sometime we need to go by the justice. No has the right to kill another life in this world.