My new research project analyzes the weight of collective memories on the foreign and security policies of the European states. This research question emerges from the observation that the past is “present” in international relations. To quote only one example, Y. F. Khong recounted that American senior officials referred 100 times to the past (mainly to the precedent of Munich 1938) during the year 1965 when they tried to decide whether intervening militarily in Vietnam or not. Most authors who addressed the topic put forward that history is mainly present in international relations through the strategic uses of policy actors. According to this line of thought, history would be nothing more than an “object” of foreign policy. To quote S. Hoffmann, policy actors would use history as a “grab bag” from which each advocate can pull out a “lesson” to prove his point. My approach takes the opposite stance. I argue that history also weights on politics by constraining foreign policy actors. To do so, I plan to focus on what seems to be a “strong case”, namely the presence of history in British, German and French strategic thinking. My intuition is that this research will contribute to our understanding of the future of the European Common Security Policy.