In 1925, of the 22 countries that could be classified as democracies, only four —France, Belgium, Portugal and Switzerland— had yet to extend suffrage to women. France is an intriguing exception: as a co-belligerent in WWI, the country experienced the type of social upheavals most commonly associated with the extension of women’s rights, most importantly a rapid increase in female labor force participation. What explains this French exception? Why did the French political elite fail to translate post-war calls for suffrage extension into policy? Mass warfare, we argue, has implications for rights expansion only to the extent that it disrupts the pre-war political equilibrium that had kept expansion off the docket. We hypothesize that, in the French case, a large death toll (16 percent of working age men, the largest of all belligerents), and its uneven distribution across the territory, ultimately re-enforced the exclusionary pre-war political equilibrium instead of undermining it. Using a unique dataset of constituency-level military death rate matched to pre- and post-war data on elected officials' position on women’s suffrage, we show that the death toll was partisan: deaths disproportionately affected the electorate of the centrist pivotal party, amplifying pre-war concerns that extending suffrage to women would adversely affect the party’s political future. We also show how existing political institutions entrenched the policy preferences of this party by giving its members veto power in the Upper Chamber. It would require a second world war, which wiped away Third Republic political elites, for this exclusionary equilibrium to come to an end.