Sounding the alarm bell to set official mobilization into motion is a process that has been regularly diverted to call for uprising. But the efficiency of this initiative does not go without saying. First of all, its tangible reception is not self-evident. Furthermore, even in the case of a reaction, convincing the people who ran to take up the arms to participate in a popular uprising is a crucial step that needs to be overcome. The alarm bell instigates a phase of intense politicization, which, because of the vagueness of the available sources, remains virtually unknown, It underlines the limits of the usual metaphor of « contagion ». The exact nature of the alarm is also problematic because of the various forms it takes through time and space. It is hard to determine if it corresponds to a specific alarm sound.