In July 2016, Gerry Adams, Sinn Féin's president of more than 35 years, was interviewed in his Leinster House office by VICE News’ Katie Engelhart. Asked, “In a way, Brexit is a gift for you, right? You campaigned against it, but now that it's happening, you’re using it to make the case for a United Ireland”, Adams responded, “Yeah, well, you always have to never waste a crisis, never waste a difficulty” (VICE News 2016). This question, and Adams’ answer, are illuminating. They speak to the somewhat ambiguous position that Irish nationalism, in general, and specifically Sinn Féin – as the largest nationalist party in Northern Ireland and biggest all-island party – found itself in after the Brexit referendum. On the one hand, Brexit posed an intrinsic challenge to the kind of actually-existing North–South cooperation, cross-border connectivity and all-island integration that has given subtle but increasingly concrete expression to nationalist political identity since 1998. On the other hand, the political and constitutional upheaval that the referendum brought in its wake provides perhaps the best chance that nationalists have had in the one hundred years since partition of seeing their aspiration to Irish unification fulfilled.

Brexit has thus created risks and opportunities for Irish nationalism, and different nationalist agents have sought to make sense of and navigate the critical constitutional moment it has represented. Here we define “nationalism” broadly as encompassing those, on both sides of the border, whose primary political identity is Irish, and who share a political aspiration to Irish (re)unification. More particularly, we are concerned here with those political parties and movements whose policy programmes seek, to a lesser or greater extent, to give expression to Irish identity and the aspiration to unification.