This article is an account of the mid-Victorian conservative reaction to the increasing prominence of the notion of nationality in British debates on European affairs. Conservatives perceived the idea of nationality as a threat, which they tried to deflect by deploying three sets of arguments. They attempted to marginalize the notion by reframing nationality as neither a valuable nor a fundamental aspect of political life; they argued that the sentiment of nationality increased aggression in international affairs and was a threat to the European order; and they argued that nationality was often incompatible with constitutional liberty and a proper patriotism, thereby presenting liberals’ support for nationality as inconsistent with their own values. This conservative rejection and problematization of nationality in mid-Victorian Britain has been absent from existing scholarly work, which has focused on the qualified acceptance of the notion by Victorian liberals and Edwardian conservatives.