This chapter focuses on separatist terrorism in Brittany and Corsica and provides a brief summary of the scholarly debate on how best to deal with the demands of recalcitrant ethno-nationalism. It analyzes the responses of French governments over time to the emergence of ethno-nationalism in Brittany and Corsica and to its escalation to violent separatist terrorism. Important difference between Corsican and Breton experiences with the Jacobin state was the impact of the French Revolution. The Revolution was a direct assault on the two pillars of power—the aristocracy and the church—that had dominated Brittany for centuries. Historically, the grievances of Breton nationalists fall into three broad categories: threats to the structure of the prevailing Breton power structure, economic underdevelopment and, by extension, exploitation, and efforts by the French state to eradicate Breton culture and language. With respect to the accommodation of Breton nationalist demands, the French government has moved only minimally and grudgingly to address the core concerns of Breton nationalists.