War minus the shooting or a pathway to peace? These two quite polarised perceptions have tended to dominate analysis of the relationship between sport and war. In this paper, I will be showing how each of these views is present, both in terms of general discussions about the relationship and specifically in relation to World War One. My analysis argues that the relationship is never unidirectional: sport can be a vector for conflict or a vector for peace, depending on the precise circumstances. And the circumstances depend on the particular contexts for any sport or war. My analysis will move on to consider the socio-political context of sport and rugby around the time of the First World War, indicating how it contributed to transformative change in the post-war years.