Escaping Nazi annexation of Austria, Sigmund Freud and his family left there in 1938 to live the rest of their lives in exile in the house now known as the Freud Museum in London. This paper is based upon the author's Holocaust Day Memorial Lecture delivered virtually at this museum on January 27, 2021, which marked the 75th anniversary of the liberation of Auschwitz-Birkenau, the largest Nazi death camp. Besides remembering those who were lost during World War II, the content of this paper includes a description of different types of massive traumas, with a focus on disasters at the hand of the Other, and their impact on individuals and large groups. Sigmund Freud's ideas about relationships between communities and countries with adjoining territories, as well as large-group psychology, are updated, and individuals' and large groups' needs to grasp onto large-group identities is explained and illustrated with case reports.