Book excerpt: In this innovative account of the origins of the idea of the League of Nations, Sakiko Kaiga casts new light on the pro-League of Nations movement in Britain in the era of the First World War, revealing its unexpected consequences for the development of the first international organisation for peace. Combining international, social, intellectual history and international relations, she challenges two misunderstandings about the role of the movement: that their ideas about a league were utopian and that its peaceful ideal appealed to the war-weary public. Kaiga demonstrates how the original post-war plan consisted of both realistic and idealistic views of international relations, and shows how it evolved and changed in tandem with the war. She provides a comprehensive analysis of the unknown origins of the League of Nations and highlights the transformation of international society and of ideas about war prevention in the twentieth century to the present.