War is the ultimate test of political systems. In France alone, the First Republic, First Empire, Second Empire, Vichy France, Third Republic, and Fourth Republics all collapsed due to strains of war. Similarly, loss in WWI proved the end of several strains of government. In the United States, the American Civil War prompted Lincoln to more or less tear up the Constitution (although it should also be noted that many provisions only apply in times of peace).
Merely asserting that Western governments are immune to the foibles of fascism and dictatorship is folly. While I agree that many countries have fairly strong checks against reversion from democracy, a prolonged period of weakening could still very well happen.