By considering the genocides of the long nineteenth century, their origins and motivations and justifications, this chapter deals with events that shape contemporary undertakings and understandings. Historians have always been at the forefront of comparative genocide studies, and the explosion of historical literature surrounding once-obscure genocidal events in the nineteenth and early-twentieth centuries has been the central component of the genocide literature for the past two decades. The roots of the 1994 Rwandan genocide of Tutsis are traced to first German, then Belgian colonization from the nineteenth century to post-Second World War. Scholars of the Armenian genocide during World War One depict it as the climax of successive waves of anti-Christian violence during the “Unweaving” of the Ottoman Empire. Perhaps most remarkable are the paradigm shifts surrounding the most iconic genocide, the Nazi Holocaust. If the French revolutionary assault on the Vendee was politically targeted, the genocidal war in Saint-Domingue reflected primarily economic and geostrategic motives.