In the cycle of total war, population displacements constitute both an issue, a sequence in the history of states and a new modality in their relations with international organizations that emerged during the two world wars (1914-1945). We would therefore like to examine the original case of the end of the Second World War in the 2nd half of the 1940s, which corresponds to the time when a new international system was being constructed that took charge, in an unprecedented and global way, of population displacements between States and populations as a specific issue in inter-State relations, in their geopolitical, economic and humanitarian dimensions (1944 to 1951, until the creation of the UNHCR). It is proposed to examine 3 main aspects of the question posed. It will be a question of making an inventory of the jurisprudence of population movements in the short time of the 20th century in relation to the history of human mobility in order to specify the object studied. It is the post-war phase that still requires study in order to appreciate the institutional and legal, humanitarian and cultural, diplomatic and economic dimensions of displacement. The humanitarian and diplomatic dimension is now a specific issue in international relations, through humanitarian diplomacy combined with explicit economic imperatives in the search for manpower by states faced with the demographic catastrophe that the Second World War represented for many of them, particularly at a time of economic reconstruction. The study of displaced populations in themselves offers another scale analysis to grasp the singularities of regional, cultural and national experiences of population displacement.