This article asks how, when, and why people came to mobilize en masse in the name of the Tunisian nation against French Protectorate rule. Rather than taking anti‐colonial nationalism as an inevitable response to the imposition of colonial rule, the account offered here insists that it is an outcome to be explained. Building on more recent theoretical directions that stress the processual, relational, and eventful dynamics of nationalism, the article shows that nationalism and nationalist mobilization cannot be attributed simply to the workings of nationalist intellectuals, to long‐standing grievances, or to larger macro‐level transformations. Rather, seeing nationalism as part of struggle and as a domain in which various forms of contentious politics are played out, I show how attention to a particular contentious event in the anti‐naturalization campaign can help us to understand how a certain version of the nation becomes salient as a mobilizing rubric for mass‐level mobilization and how various forms of contention coalesce to produce nationalist outcomes.