During the rise of fascism and anti-Semitism in Germany, Albert Einstein wrote to Sigmund Freud asking the fundamental question: What can be done to liberate humanity from the menace of war? The psychoanalyst replied at length and their exchange of letters (reproduced here) was published in March 1933 under the title Why War?. The book would be included in the book burnings in Berlin on 10th of May that year. Why War? is important in Freud''s work because in it he develops a fundamental idea that leads him to conclude that the life and death drives are linked - a thought that he had already entertained in works such as Death and Us (1915), which is also included here. In a terrible irony, Freud dedicated a copy of Why War? to Mussolini, who nonetheless instituted a police investigation of its author. The contributors to this volume explore the reasons underlying the dedication, as well as giving their own reflections on the genesis of war.