This chapter discusses similarities and differences in the emergence (including planning and construction), functions (mass murder, forced labor, utilization of looted property), and operations (killing techniques, connections to the “outer world”) of German mass extermination sites, the importance of “knowledge transfer” (from “euthanasia” killings to “Aktion Reinhard,” from prewar concentration camps to Auschwitz); addresses forms and levels of involvement of these sites and their staff in the “Final Solution” and the murder of other groups (also vis-à-vis non-German killing sites and German mass shooting sites) within the broader context of the Nazi project and its systemic dynamics.

Genocide and ethnic cleansing are forms of political violence because they politicize nationality, ethnicity, race and religion. Branded as traitors or feared as security threats, minority populations have been murdered and deported in astonishing numbers during Europe's long twentieth century. Why these phenomena accelerated and peaked in its first half, in particular, remains in dispute. The burgeoning scholarly literature on genocide and ethnic cleansing tends to fall into one of two categories. It is concerned either with one individual episode or perpetrating regime, or with comparing the phenomenology of different genocides across large tracts of time and space. With a few notable exceptions, it rarely explores extensive causal or contextual interconnections between different cases. As a relatively small global region, the Europe of the long twentieth century is a spatio-temporal setting that lends itself very well to examining the relationship between ostensibly separate episodes and, along the way, problematizing or dismantling some of the simplistic explanations that have hitherto held sway about the relationship between specific sorts of ideology, regime and state form and the mass murder or violent eviction of civilian populations.

Contrary to the accumulated history of ideas of racism and ethnonationalism that often passes for explanation of genocide studies, the pure, abstract logic of exclusionary ideology is rarely sufficient to push even extremists into ethnic cleansing or genocide. How and how far a goal of homogeneity is pursued depends upon the contingent course of events.

During recent years a series of important studies have attempted to deal synthetically with violent aspects of European history in the twentieth century. All of them refer to and replicate aspects of Eric Hobsbawm's masterpiece Age of Extremes: the Short Twentieth Century 1914–1991 (1994), which in turn demarked that century from the ‘long nineteenth century’ with which Hobsbawm concluded his Age of Empire 1875–1914 (1987). Key analyses in the ‘classic’ works of Volker Berghahn, Ian Kershaw and Mark Mazower share three broad arguments: first, they demonstrate the important role played by ideologies. Liberalism, different variants of aggrandizing nationalism, including colonial imperialism and Nazism, as well as socialism and Soviet communism were, in different phases, instrumental in intensifying political violence (or, as Kershaw terms it, ‘state-sponsored violence’) during the twentieth century. Mark Mazower reminds us in this respect of two realities: during the twentieth century, Europe was not on the whole shaped by a convergence of thinking and feeling, but by a series of violent clashes of diametrically opposed New Orders; and National Socialism, fascism and communism were not alien or novel imports into Europe but grew out of the heritages of previous periods of European history. What was new therefore in the twentieth century was not that there were such ideologically driven conflicts, but their intensity. This owed something to the novel harshness of the expression of these ideologies, but was also a consequence of new means of expression.

That Europe's twentieth century was a period of exceptional violence is certainly not a novel insight. For decades, historians, social scientists and anthropologists have investigated the various forms of more or less organized political violence that occurred in Europe's diverse cultures, ranging from war to genocide and expulsion, from revolution to state repression. Yet no study exists that attempts to explain the emergence and manifestations of, and interconnections between, different forms of political violence within the confines of one volume. In addition, the emphasis which has often been placed on the role played by national political contexts, or more strongly by national peculiarities, in explaining violence has tended to preclude examination of common European trends in the emergence of political violence.

Against this background, the book differs from the existing scholarship in three distinct ways. First, it adopts an inclusive approach to political violence. After an opening chapter that seeks to establish general patterns of causation and periodization in political violence across what we term the ‘long twentieth century’, the volume systematically examines four expressions of political violence, each of which contains its own dialectical dynamics: the violence of military conflicts; the violence generated by projects of genocide and ethnic cleansing; the violence of terrorism and of state repression; and, finally, the violence of revolution and counter-revolution. The volume locates each of these manifestations of political violence in transnational and comparative contexts, and seeks to relate them to each other, and, in turn, to broader trends in European history.