The sources and nature of ‘radicalism’ in late eighteenth-century Britain have long been debated. At the same time, the impact of war on British politics, society and culture in this period has been underappreciated until recently. While war is recognized as having aided the spread of popular loyalism, its role in stimulating radicalism has been neglected. Based on study of the publications and letters of Richard Price (1723–91), this article highlights the influence of Anglo-French rivalry and war on the thought of a leading Rational Dissenter and champion of political reform.