This paper makes a contribution to the debate about the interplay between military action and humanitarian aid. It takes on the case study of post-World War Two Europe and in particular the activity carried out by the United Nations Relief and Rehabilitation Administration (UNRRA), which offers a useful key for highlighting the entanglements between relief and reconstruction projects. It is from this perspective that the interaction between humanitarianism and military undertakings also acquires a special meaning, which recalls both the development of the international aid regime and the post-war history of Western countries. The matter will be addressed from two points of view. First to be analysed is the set of agreements stipulated by UNRRA and military authorities, for the zones under Allied administration after the liberation, but also with respect to specific areas of intervention, like the Displaced Persons Operations. The terms of the official agreements allow the delineation of the tasks actually assigned to the agency by the United Nations and the role of control and protection reserved for military organizations. Based on the formal agreements, it is already possible to reconstruct a vision of relief understood as the result of the inextricably linked action of military and humanitarian actors. Next, the interplay between different interpretations of activities to help civilians affected by the war will be examined. This section will focus on the personnel deployed by UNRRA, on their origins, and on duties they are called on to fulfil. People with extensive experience in the welfare sector were a substantial part of the personnel, but a significant number of UNRRA employees came from military ranks. This essay, therefore, has a twofold objective. It analyses the normative and institutional frame that shaped relief work in Liberated Europe. At the same time, it aims to uncover competition and cooperation between military and humanitarian actors in the field. The aim is to highlight how the co-construction of the aid operations between military and civilian personnel that occurred during the second post-war period followed a series of complex, nonlinear paths that conditioned the development of the humanitarian regime from within.