The French losses of the Great War are mainly known through the report of the deputy Louis Marin, who himself thought it not fully satisfactory. Analysing the sources and bases of Marin’s computations throws some light on the system adopted by General headquarters to count killed, missing and wounded soldiers. In this way, it becomes possible to account for the accuracy of those figures and to explain the differences between three estimates : first, the losses of the French army, second, those of the French population and third, the number of soldiers “killed for France”. The very idea of one precise, reliable estimate of the losses of the Great War thus loses its meaning. For French civilians, numbers were not as crucial as the names of the dead : they asked for lists, not figures.