The guy standing right in the front with both of his arms on the rail is named Adolf Hitler. He is no ordinary guy he was the main guy of the Holocaust. It was his ideal to kill a genocide of Jews. Adolf didn't like the Jews because felt that they were the reason why World War One was caused.
Due to google the definition, of the holocaust, is , "The Holocaust, also referred to as the Shoah, was a genocide in which some six million European Jews were killed by Adolf Hitler's Nazi Germany, and the World War II collaborators with the Nazis."