Brian M. Downing. 1992. The Military Revolution and Political Change: Origins of Democracy and Autocracy in Early Modern Europe. Princeton: Princeton University Press. Chapters 1 (“Introduction”), entire, and 10 (“Conclusions”), particularly pp. 239-242, 246-251.
The representative assemblies of late medieval Europe constituted a basis for liberal democracy. A dangerous military situation precludes or destroys constitutionalism and fosters an authoritarian, military-bureaucratic state, especially when countries rely on domestic resources to finance modern armies.