What was cruel things in World War I that Germans did?

After World War 1 was over Germany took all blame because allied powers made them responsible in the Treaty of Versailles. Hitler, the powerful leader of Germany, declared war and said Jews were the reason Germany lost world war 1 so that started the Holocaust. so cruel things. Germans used to throw Jewish babies in the air and shoot them and others were killed because they starved to death and at some camps they gave you small portions of food so they lived longer!