During the major revolutionary upheavals around 1800, societies and states in the Atlantic world grappled with complex questions of political belonging. While scholars have come to view the rise of modern citizenship as a long and protracted process, the revolutionary period is still considered as a time of dramatic disambiguation of political belonging, a moment in which members of political communities were more sharply distinguished from non-members, and previously fluid boundaries of belonging, while not disappearing, hardened. This subproject sheds light on a process that has so far been insufficiently linked to the question of the reconfiguration - and alleged disambiguation - of belonging. As a result of revolutionary upheavals and violent conflicts, political refugees became a mass phenomenon during the revolutionary era. In response to these migrations, national and colonial governments created legal regulations, often for the first time, to control the mobility of foreign refugees and, more broadly, regulate the status of strangers. First, based on a systematic survey and context-based case studies of these efforts at migration control, the subproject focuses on a comparative and relational reconstruction of the reregulation of alienness and questions its significance in reconceptions of belonging. In this way, it examines for the first time systematically the extent to which the border between citizens/subjects and foreigners was not only redrawn from within, but also from without – by redefining the position of those who did not belong. Second, the subproject focuses on the Caribbean, one of the most important laboratories of migration control at the time. Through this geographic focus, it brings into view complex processes of determining belonging based on distinctions of confessional affiliation, race, and gender - and their interplay - and interrogates their repercussions on European colonial metropoles. At the same time, it uses the examples of the Dutch and British Caribbean to examine the extent to which imperial and geostrategic practices of tolerance for ambiguity persisted.