The Ecclesiastical Province of Cambrai may sound unfamiliar to modern readers. The bishopric of Cambrai dates to the sixth century but only became an archdiocese and, consequently, the centre of a church province in the sixteenth century. The elevation of the see resulted from the heavily contested reorganization of the diocesan map of the Low Countries by King Philip II in 1559. The new province included the medieval sees of Arras, Cambrai and Tournai, as well as the newly created bishoprics of Saint-Omer and Namur. Its borders were established to encompass the French-speaking Walloon provinces in the south of the Low Countries, territories that are now divided between France and Belgium.1 In the early modern period, this area was already a border and transit zone between France, the Low Countries, the Holy Roman Empire and the British Isles. The province’s history in the sixteenth and seventeenth centuries was deeply marked by recurrent and devastating warfare between the kings of Spain and France, eventually resulting in the transfer of significant territory to France.2 However, the Province of Cambrai was also the scene of frequent cross-border mobility, and a safe haven for Catholic exiles originating from the British Isles, France and other parts of the Low Countries.