Ce mémoire ré-explore la thèse de la centralisation du pouvoir aux niveaux supranational (UE) et national (Allemagne) lors de la crise des migrants de 2015. Cette thèse est largement étudiée et reconnue dans le domaine de la gestion des crises et prend place soit par une approche descendante - les niveaux supérieurs agissent unilatéralement - ou par une approche ascendante - les niveaux inférieurs délèguent aux rangs supérieurs. Au cours de la crise des migrants de 2015, il est attendu que la centralisation aux niveaux national et supranational prenne place avec l’intensification de la crise et par une approche descendante. Le document examine la crise de manière quantitative et présente une analyse de contenu chronologique de 94 déclarations officielles de la Commission Européenne et du gouvernement allemand. Les résultats obtenus confirment la validité de la thèse de la centralisation du pouvoir, son lien à l’intensification de la crise ainsi qu’une approche ascendante. / This research paper assesses the well-known centralization-of-power thesis and analyses it at both the supranational level (European Union) and the national level (Germany) during the 2015 migrant crisis. The centralization-of-power thesis is a widely studied and recognized phenomenon in the field of crisis management building on the subsidiarity principle saying that power tends to be centralized in the hands of the highest ranks of a hierarchy when lower ranks are unable to cope with a crisis. The centralization can either take place through a top-down approach – highest ranks take the lead unilaterally – or a bottom-up approach – lowest ranks deliberately delegate power to the higher ranks. According to this thesis, in the case of the 2015 migrant crisis it is expected that the centralization of power happened at both the national and supranational levels as the context aggravated but also through a top-down approach, due to the complex context of the European Union and the highly decentralized structure of German federalism. The paper first examines the 2015 migrant crisis from a quantitative standpoint, tracing its evolution and aggravation. It also presents a computer-assisted content analysis of 94 official statements issued by the European Commission and the German Federal Government’s officials in response to the 2015 migrant crisis. The paper then provides a detailed analysis of the qualitative and quantitative evidence recovered that led to three main conclusions. Firstly, the centralization of power is observed at both the supranational and national levels during the 2015 migrant crisis, but in significantly different ways. Secondly, the centralization of power can be seen as triggered by the aggravation of the context and to the intensification of the crisis. Lastly, it was put into place as a top-down approach; it was German and European’s high officials that took over the crisis management effort and constrained lower levels of government to act accordingly.