Here is evidence for the Roberts Higgs thesis and, if I recall correctly, some recent remarks by Thomas Piketty on revolution and tax progressivity (does anyone know the link?). Juliana Londoño Vélez writes:
Abstract I argue that progressive income taxation in the twentieth century is a product of the exigency of war and not of democracy. I obtain long-run series of the top marginal personal income tax rate for a large sample of OECD countries, and use data on wars of mass mobilization and democracy from the Correlates of War data set and Scheve & Stasavage (2012) to test this hypothesis. My results suggest that wars of mass mobilization (i.e. wars in which more than 2% of the population served in the military) cause substantial increases in tax progressivity. These effects are persistent and do not vanish upon the conclusion of war.
The full paper is here (pdf), taken from the generally interesting Berkeley Economic History Lab list, as cited by Barry Eichengreen. As Barry notes, see also the revised and much improved version of Lemin Wu’s paper on the Malthusian trap (pdf).