The significance of the Bryce Group and the League of Nations Society in promoting the League of Nations idea during the First World War has frequently been noted but has previously escaped detailed historical attention. In Britain and the Intellectual Origins of the League of Nations, 1914–1919 , Sakiko Kaiga addresses this important historiographical deficit. After a brief overview of the longer-term intellectual roots of the idea, Kaiga considers the Bryce Group and the League of Nations Society in turn, followed by evaluation of the transatlantic dimensions of their work and the transformation of their ideas towards the conclusion of the First World War. The discussion of the Bryce Group's proposals in chapter 2 is especially valuable for Kaiga's nuanced and original consideration of their development of ideas subsequently labeled “collective security” (41). A further highlight is Kaiga's rich elucidation in the subsequent chapters of the compromises that advocates of the league had to make to popularize the idea when confronted by public opinion that was far from the pacific force that was hoped would underpin the league's success. For students of transnational history, the analysis in chapter 4 of the relations between the League of Nations movements in Great Britain and the United States provides an immensely insightful case study of the tensions inhibiting transnational cooperation even between groups with apparently complementary objectives. The narrative is based on detailed and careful archival research throughout.

The account of the league's origins that Kaiga presents in this volume is a story of elite British men and their networks. Despite Kaiga's claim that these were “the original pro-Leaguers” (159), reliance on this book alone would provide picture of the immediate-term intellectual origins of the League of Nations that is far from complete. The contribution of women to the origins of the League of Nations is a notable omission from the volume. The International Congress of Women held in the Hague in April 1915 put forward extensive proposals for the “organization of the Society of Nations,” including enforcement mechanisms (Report of the International Congress of Women [1915], 13), and a British woman, Chrystal Macmillan, was among those who were appointed to serve as envoys to present these proposals to heads of state including US president Woodrow Wilson. Kaiga's decision to limit her focus to organizations such as the Bryce Group and the League of Nations Society and to overlook the contributions of individual activists such as Macmillan obscures important parts of the wider British intellectual roots of the League of Nations, such as the role of women and broader social movements.

Kaiga is also highly dismissive of contributions to the intellectual origins of the League of Nations from outside Great Britain. French contributions, for instance, are cast aside as “government-led and only intensified after 1917” (13). Although she acknowledges the ideas of French statesmen such as Léon Bourgeois, wider continental European contributions to the immediate-term intellectual origins of the League of Nations are largely absent from her consideration. For instance, acknowledgment of the work of Belgian internationalists Paul Otlet and Henri La Fontaine, both of whom put forward detailed proposals for postwar international organization, is missing from the volume (apart from noting La Fontaine's membership of the League of Nations Society) despite their significant influence on British League advocates such as Leonard Woolf. While Kaiga may be justified in arguing that British internationalists largely eschewed institutionalist approaches prior to the First World War (36), the same cannot be said of many continental European thinkers whose approaches were taken up in Britain following the onset of the conflict.

Kaiga is to be commended for her nuanced consideration of problems of the approaches to international organization put forward among British internationalists during the First World War, including their Eurocentrism and questionable conceptualization of progress. Kaiga nevertheless asserts in chapter 4 that the proposals of the British League of Nations Society were more “realistic” (104) than those of the US League to Enforce Peace given the latter's emphasis on international armed force, but this argument appears to contradict Kaiga's assessment in chapter 2 of the “realistic” (44) nature of collective security proposals in comparison to those that rely on public opinion. The discussion of how “realistic” Kaiga considers the various proposals to be is further undermined by the unsustainable parallels she draws between the conception of “realistic” in this book and realist international relations theory (162), an approach that is wholly incompatible (in all its many variants) with proposals for collective security. These arguments are a distraction from the exceptionally rich, archivally informed narrative that makes this volume essential reading for those interested in discovering more about a key component of the British intellectual roots of the League of Nations.