How much influence does the regime type of a country have on its ability to win an international war? Upon closer inspection, very little. A careful study of the process by which peaceful citizens are converted into instruments of state-sponsored destruction shows that countries with democratic systems of government perform no better in international wars than their non-democratic counterparts. Instead, it is the size of the population asset that the state's leadership can gather, leverage, and deploy in combat that has historically mattered most for victory in war. Population sizes of countries in the international system are so varied that it is virtually impossible for a small nation to withstand the military onslaught of a more populous foe, a finding that reintroduces some basic tenets of realism to modern foreign policy discussions. The importance of the size and quality of a country's population is demonstrated via statistical analysis on a novel dataset of international wars since 1816, as well as detailed case studies of the Arab-Israeli Wars and German invasion of France in 1940.