The return of authoritarian great powers, the slowing of the democratic wave, and outright reversion to authoritarian rule pose important questions for international theory. What are the implications of an international system populated with more autocracies? This question was posed by a diverse array of social scientists, public intellectuals, and policy analysts in response to the autocratic wave in Europe in the 1920s and 1930s. We show that a series of conversations emanating from quite diverse intellectual priors – from Christian realists to international lawyers and disaffected Marxists – converged on the risks these autocratic regimes posed to democratic regimes and the international order they sought to forge. These risks included unconstrained rulers, an inability to sustain international commitments and political processes that undermined rational deliberation at home and spread disinformation abroad. The reading of this work suggests an under-appreciated strand of liberal international relations theory, and these debates have direct implications for liberal arguments about the democratic peace. Rather than theorizing why democracies avoid war, they underscore the importance of understanding why authoritarian and democratic countries are particularly prone to conflict.