The creation of pacifist international organizations are consequences of the horrors of the First and Second World War. In 1919, the Covenant of the League of Nations acknowledges the importance of education in the enhancement of pacifism. Two decades later, the Constitution of the UNESCO declares that “it is in the mind of men that the defences of peace must be constructed”, and education is set as one of the three pillars of the organisation. For the League of Nations as well as UNESCO, the knowledge of cultural heritage constitutes one of the main educative considerations. These two organisations play a major role in the evolution of the place assigned to cultural heritage in the 20th century. Initially reserved for the elites, cultural heritage gradually becomes a media for educating people to tolerance and cultural understanding. This paper will trace the history of the pacifist vision of cultural heritage conveyed by the League of Nations and UNESCO, from the 1920s to nowadays. By focusing on the international networks and educational programs implemented, we will examine what transnational vectors have been used in order to disseminate pacifist ideas.