That is the new NBER working paper by Alberto Alesina, Bryony Reich, Alessandro Riboni, here is the abstract:
The increase in army size observed in early modern times changed the way states conducted wars. Starting in the late 18th century, states switched from mercenaries to a mass army by conscription. In order for the population to accept to fight and endure war, the government elites began to provide public goods, reduced rent extraction and adopted policies to homogenize the population with nation-building. This paper explores a variety of ways in which nation-building can be implemented and studies its effects as a function of technological innovation in warfare.
That is related to some recent work by Ferejohn and Rosenbluth.