Thomas Fischer's Die Souveränität der Schwachen is a long, well-researched book of international history that traces Latin America's role in the League of Nations from its foundation at the Paris Peace Conference in 1919 to its dissolution during the Second World War. Fischer offers a new look at the arena of global politics of the interwar years, in which Latin America initially constituted one-third of the membership of the League, but had limited power in the European-dominated organization. He convincingly uses Latin America's intertwined history with the United States to illustrate why their membership in the League of Nations – whose proclaimed goal was to protect the sovereignty and independence of its members, and to solve future conflicts through peaceful resolution – was so important. Within the context of the organization, some of the stronger Latin American nations, such as Argentina and later Brazil and Mexico, used their limited power to provoke the European-dominated League to adhere to its own ideals, while the weaker Latin American nations, such as Cuba and Nicaragua, used the forum to demand protection from continual direct threats from the United States. As the United States policy toward Latin America changed with the proclamation of the Good Neighbor Policy by President Franklin Roosevelt in 1933, many Latin American nations felt that their membership in the League of Nations had become obsolete.

While the book title seems to suggest a homogenous Latin America, Fischer never presents the region as a monolithic bloc. Instead, he carefully evaluates attitudes and reactions individually, based on evidence from primary sources from archives in Latin America, Europe, and the United States, and evaluates a broad range of secondary sources to present a more complex picture. He makes clear that Latin America was divided by distinct socioeconomic needs, cultural compositions, and political developments and characterized by conflicts, competition, and diversity in perceptions and attitudes. This heterogeneity impeded regional unity within the League of Nations and thus decreased Latin America's political leverage. Although many attempts were made to create a more unified regional perspective in Geneva and to strengthen the continent's position vis-à-vis the United States (for example, by invoking nineteenth-century ideals such as bolivarianísmo and hispanidad), unification efforts only had limited success. The incapability of Latin American delegates to collaborate on overarching regional goals, paired with their lack of diplomatic experience, led to the result that many Latin American nations that had placed high hopes on the League stopped believing in its effectiveness and eventually left it or retreated from it. However, as Fischer points out, participation in the organization taught Latin American delegates many lessons that helped them to present themselves better in global fora thereafter and taught them effective techniques such as strategic voting to reach their political goals.

Fischer examines the development of the League of Nations and the relationship between delegates from the Old and New Worlds by including global politics as well as country-specific political, socio-economic and cultural factors into his analysis. Fischer mainly looks at official interactions of the delegates during meetings, but he also allows a glance behind the scenes and investigates the delegates' private meetings during their stay in Geneva. In doing so, he draws attention to the main dichotomy that Latin American delegates faced within the organization: on the one hand, the strong European nations required the backing of the ‘smaller’ or ‘weaker’ nations as active participants to underline the organization's credibility; on the other hand, the same powerful European representatives possessed a colonial mindset that rendered them unable to accept the Latin American delegates as equals and perceive their needs as equivalent to those of more powerful nations. This meant that Latin American delegates kept encountering discrimination based on racial and national criteria from within the organization. As Fischer points out, nationality and race, rather than skills and knowledge, served as key factors for hiring individuals at the office in Geneva, which led to Latin America being significantly under-represented among the staff of the permanent administration.

As Fischer points out in detail, for the Latin American nations Article 21 of the Charter of the League of Nations was highly controversial. In it, the organization stated clearly that it would not interfere in regional understandings such as the Monroe Doctrine. While most Latin American delegates tried to change this article in some way, Europeans respected the hemispheric hegemony of the United States in the New World and were more focused on stabilizing politics within Europe than willing to support Latin American delegates in their request for help against the United States. While the League played an active role in solving two territorial conflicts in Latin America – the Leticia Dispute (1932) between Colombia and Peru (where the first peacekeeping soldiers were employed) and the Chaco War (1932–35) between Paraguay and Bolivia – its main concern lay in the creation of a stable and secure Europe, so that affairs on the periphery only played a secondary role.

While this book should be evaluated as a contribution to the fields of Latin American history, US–Latin American relations, and global political systems in the interwar years, it remains unclear why Fischer, who is fluent in several languages, chose to limit the book's exposure to those capable of reading German. A much broader audience would have been reached had the author published in English or Spanish. One can only hope that the scholarship that Fischer presents here will be disseminated more broadly soon, and that a translation into English or Spanish is envisioned that will ensure that his argument can be part of the broader discussions in the field.