Drawing on recent thorough‐going debates on ‘geographies of peace’, this paper addresses the experience of the French geographer Paul Dupuy (1856–1948) and his daughter, Marie‐Thérèse Maurette (1890–1989), in the Geneva International School between 1924 and 1948. Working with primary sources, I reconstruct their teaching of ‘synthetic geography’ and ‘international culture’, which aimed to establish didactic methods for peace education employing current geopolitical issues. I discuss this early experience in geographies of peace in order to put it in its historical and international contexts and to give a contribution to present geographies and geopolitics of peace, by underscoring the importance of internationalism and voluntarism. The main arguments of this study are the importance of multilingualism and cosmopolitan mentality, and the problems that politically committed geographies often found with institutions and ‘national schools’: the context of Dupuy's and Maurette's teaching was completely exterior to academia and marked by a strong voluntarism. In this, it joined former examples of extra‐institutional and engagé geographical networks, like those of the anarchist geographers Reclus and Kropotkin and of anarchist education, a tradition which played a role in inspiring Paul Dupuy's works.