Imperial Boundaries: Cossack Communities and Empire-Building in the Age of Peter the Great by Brian J. Boeck is a recent monograph on the changing roles of the Cossacks in the frontiers of Russian imperial expansion. Boeck uses the analytical category of the "middle ground" to understand the relationship of the Don Cossacks to Russian state on the frontier. At the Edge of Empire: The Terek Cossacks and the North Caucasus Frontier, 1700-1860 by Thomas M. Barrett also uses the "Middle Ground" as a methodological framing device. Tsar And Cossack 1855-1914 by Robert McNeal examines the Cossacks from the perspective of their evolving relationship with the Romanov state. McNeal pushes a somewhat orthodox interpretation that the Cossacks' way of life was fading and unsustainable by the early twentieth century. Shane O'Rourke's Warriors and Peasants: The Don Cossacks in Late Imperial Russia adds a qualifier to this pessimistic assessment and is quite strong on local institutions, although various reviewers questioned his wider assertion that the Cossack nation was restoring an older independent polity. Peter Holquist's Making War, Forging Revolution: Russia's Continuum of Crisis, 1914-1921 has a number of sections on the cossacks during the Revolution and Civil War.