Welfare ministries are key institutions of modern nation-states. However, we still lack knowledge about when and why national welfare ministries were established. In this paper, we argue that both the First and Second world wars were major driving forces behind the establishment of independent welfare ministries. To test our argument, we introduce a novel dataset on the establishment of welfare-related ministries in 30 countries. Our empirical findings suggest that the establishment of independent welfare ministries was a product of wartime turbulence and the political, economic and social shockwaves set off especially by World War I, which affected many countries at the same time. Considering alternative explanations such as the Spanish Flu, the Bolshevik Revolution or the emergence of new nation-states, we argue that war triggered multiple, interrelated and chronologically staggered transnational events and transformations that had major effects on the social welfare systems of the countries involved. In this light, we conclude that World War I was ultimately the root cause behind the establishment of welfare ministries.