In this exceptional study, the author goes beyond the sphere of party politics to explore the industrial aspects of French wartime history. During the First World War, French citizens accepted national union on the home front as a necessary act of self-defence, but not without a considerable degree of ambivalence. At the political level, this union altered the balance of forces by improving the position of the Right, destroying the identity of the Radical party and creating the means by which the Socialist party first had access to power. However, what makes this study exceptionally important is that beyond the sphere of party politics it also deals with the industrial aspects of French wartime history. Industrial mobilisation was the force behind the union sacrée, but it also concealed deep conflicts of interest. While businessmen developed large corporations, new industries and scientific management, and reulctantly cooperated with an ever-expanding state, rank-and-file workers accepted concepts of productivism but rejected the sacrifices imposed upon them. Their complaints eventually surfaced in the form of open resistance. The subsequent attempt on the part of management to repress the worker's movement led to a stalemate on the home front at the end of the war.