Background The COVID-19 pandemic has required urgent organisational and managerial adaptation, with hospital medical and administrative leaders under considerable pressure. Methods At a single French university hospital, we performed a sociological analysis of management adaptation by medical and administrative leaders during the first wave of the COVID-19 crisis. Two sociologists performed interviews with representative members of staff from all the structures involved in managing the crisis to analyse adaptation and the solutions found during this period. Results The answers collected during interviews were classified into three main topics describing the organisational adaptations of the hospital staff during the COVID-19 crisis: (1) exceptional mobilisation and collaboration; (2) crisis management based primarily on the principle of subsidiarity; and (3) survival of the administrative structure with interventions to support caregivers. Conclusion This study, focusing on a single hospital, identified a number of factors associated with successful mobilisation in the very specific conditions of this viral pandemic.