There is a belief among historians that the era of modern nationalism also promoted more violent wars, as in the levée en masse of the French revolutionary armies and the World War I binge of national bloodletting. Nationalism generated patriotic sentiment and more equal and meritocratic military participation; hence the era of mass conscription (and sometimes enthusiastic volunteer) armies replaced the era of more limited battles carried out by aristocrats and mercenaries. The dark side of this nationalist fervor has been exposed repeatedly since the early twentieth century via ethnic cleansing and genocide.

The problem with this argument is that it fails to parcel out all the processes that affect fighting efficacy. Several major changes in military organization, technology, and tactics happened in the period overlapping with modern nationalism. I will argue that it was these changes that eventually made fighting more lethal, and that nationalism had at best an indirect effect, and more on the mobilization of soldiers to be killed than on their ability to kill others.