Discussing the historiography, this section posits the need to move away from national-exceptionalist theories of colonial violence and the military-historical search for national doctrines of colonial warfare, instead recognising the extreme violence of fin-de-siècle colonial wars as part of a transimperial Colonial Way of War. Research should take into view several empires and the shared thought behind such violence. Europeans racialised colonial warfare and infused it with performative aims and imperial anxieties. Such racialised notions eventually became more important than structural constraints in determining extreme colonial violence. Cross-imperial connectivity explains the highly transimperial character of this knowledge, a connectivity that rested mainly on human, colony-to-colony mobility and on transnational colonial populations. Researching this requires rethinking ideas of imperial networks and reservoirs of knowledge. The introduction also offers definitions of ‘knowledge’ in relation to colonial warfare and of ‘extreme’ violence (arguing that there was a qualitative difference between colonial and ‘European’ wars at the time) and discusses sources and periodisation.