This is the legacy of history that led to the creation of the APHP hospital network as a single entity. Its huge size is regularly questioned, both internally and externally, as an obstacle to adaptation in a rapidly changing technological, medical, and social context. The decision circuits are complex, internal rivalries may develop, and changes are slow to spread. We sensed, however, that the size of the organisation could be an advantage in times of disaster. This advantage has now been demonstrated. No lack of coordination has been identified. No leakage or delay has occurred. No limit was reached. Furthermore, we believe that such a structure is not only an advantage in times of crisis, but also on a normal day. A large hospital complex is also able to produce powerful research, to process a considerable amount of data, and to play a major part in public health. What happened strengthens our belief that size can be combined with speed and excellence. In the aftermath of this terrible experience, it is too early to report the details of the medical expense incurred and the lessons that can be learned from this event. But we already know that as terrorism becomes more lethal and violent, nothing will prevent the medical community from understanding, learning, and sharing knowledge to become more effective in saving lives. However, we must remain humble and expect deaths to occur among the severely wounded patients in the upcoming days, despite the fact that we observed only four deaths (1%) among the 302 injuried patients, including two deaths on arrival at hospital.