Popular support for war is widely understood to solidify Britain’s sense of itself in the eighteenth century. This chapter argues that objections to war shape Britain’s identity in the closing decades of the century, as the people are called upon to evaluate the justness of the nation’s acts in war. These acts are understood to be public acts, authored by each and every individual, including those who do not directly wage war. The attention to public responsibility coincides with renewed scrutiny of war’s harms, and the moral urgency of recognising and halting war’s killing animates philosophical essays, sermons, and poems, including works by Jeremy Bentham and Anna Letitia Barbauld. The period’s anti-war arguments foreground concepts of injury and responsibility that anticipate later developments in international law and ongoing discussions in moral philosophy.