after serving as a member of the sceaux "commune" council in 1935, and as a council member for seine (1938–1941), he joined the french resistance in the fight against the nazi german military occupation, and held a high-ranking position in the sfio executive committee, being the editor of the illegal newspaper "le populaire". after the liberation of paris, depreux became mayor of sceaux (a position he would hold until 1959), and a member of the "assemblée consultative provisoire" that served as the legislature of france prior to the creation of the fourth republic; he then was elected to the french parliament for successive terms between 1946 and 1958.