Although the crisis surrounding the execution of Protestants by Catholic authorities in the Polish town of Thorn in 1724 is relatively well known among historians of early modern Europe – as indeed is the susceptibility of the eighteenth-century Polish-Lithuanian Commonwealth to external interference and intervention – there has been no detailed, multi-angle analysis of the European reactions to this instance of alleged religious persecution. By analysing the diplomatic and publicity responses of various European powers, as well as the comments in the contemporary print media, a number of insights will be gained. By focusing on the arguments and language used, the article seeks to discern the normative attitudes of contemporary statesmen towards sovereignty, standards of good governance, 'enlightened' state practices, international treaty law, and the grounds and scope for the external protection of foreign subjects' rights. More broadly, this will enable a deeper understanding of the normative underpinning of the post-Westphalian states system by highlighting the previously underestimated role and capacity of intervention in states' internal affairs, stemming, at least in part, from a 'proto-humanitarian' impulse. By keeping a close watch on the broader context of European international relations, the relative importance of political and geostrategic interests in such undertakings, and how these interacted with more ideological factors, will also be explored, as will the interrelationships between the public sphere and foreign policy.