This article delivers the first comprehensive analysis of the new database, 'Mémoire des hommes', which gathers more than 1 Million French soldiers officially recognized as dead for France during WW1. Crossing this source with the 1911 census, we evaluate the potential numbers of recruits by French regional department. From this, a model identifies the factors affecting the number of dead. While demographic factors are the principal determinants, adding economic, political and locally significant factors reduces the unexplained variance between regions and significantly improves the explanation of the disparity in the number of dead by region