An Appraisal of Project Mars and the Divided Armies Argument

Abstract

Abstract Project Mars released what it claims to be a completely new dataset of 250 wars fought since 1800 and claims these data do not suffer from Western biases of other data projects (e.g., the Correlates of War [CoW]) that apparently overlook non-Western conflicts. These data featured prominently in a recent argument in Divided Armies (2020) about the negative relationship between military inequality and battlefield performance. Our appraisal of both the data and the argument advanced in Divided Armies suggests some caution with these claims. Project Mars does not amount to a completely new dataset on conventional wars. Instead, Project Mars only evaluated CoW's interstate war data, missed that the bulk of its wars are available elsewhere in CoW's data repository (i.e., as intrastate or extrastate wars), and may have missed important observations in CoW's typology (prominently intrastate wars) that could double the size of Project Mars. Combined with additional misgivings about the quality of Project Mars’ coding and how the military inequality data were not constructed as Project Mars implies, these have important implications for the core argument advanced in Divided Armies. Scholars of war should not pool wars in their statistical models as Project Mars does.