Published online: 14 November 2011We examine the relationships between warfare, taxation, and political change in the context of the political unification of the Italian peninsula. Using a comprehensive new database, we argue that external and internal threat environments had significant implications for the demand for military strength, which in turn had important ramifications for fiscal policy and the likelihood of constitutional reform and related improvements in the provision of nonmilitary public services. Our analytic narrative complements recent theoretical and econometric works about state capacity. By emphasizing public finances, we also uncover novel insights about the forces underlying state formation in Italy