“The Tyranny of Tolerance” examines France’s brutal entry into North Africa and a foundational yet unexplored tenet of French colonial rule: religious tolerance. By selectively tolerating and thereby emphasizing confessional differences, this colonial strategy was fundamentally about reaffirming French authority. It did so by providing colonial leaders with a pliant, ethical and practical framework to both justify and veil the costs of a violent conquest and by eliding ethnic and regional divisions with simplistic categories of religious belonging. By claiming to protect mosques and synagogues and by lauding their purported respect for venerated figures, military leaders believed they would win the strategic support of local communities—and therefore secure the fate of France on African soil. Scholars have long focused on the latter period of French Empire, offering metropole-centric narratives of imperial development. Those who have studied the early conquest have done so only through a singular or, to a lesser extent, comparative lens. French colonial governance did not advance according to the dictates of Paris or by military directive in Algiers. Instead, it was forged on the ground in Algeria through the negotiations of colonial officials, military leaders, autochthonous Muslims and Jews, Catholic missionaries, and European Protestant settlers over questions of religion, rule, and rights. As a colonial principle, tolerance rhetorically and structurally placed religion at the center of the imperial enterprise by identifying, managing, and legally sanctioning notions of difference along religious lines. As such, it fostered a pivotal relationship between religion and empire, a relationship that was challenged and redefined by the entreaties, resistance, and interests of Muslims, Jews, and Christians across the Algerian littoral. By initiating a dialogue between the fields of French, Jewish, colonial, and North African history, this study offers a necessary corrective; both to the history of France and its empire as well as to the history of the different communities that shaped French rule from below. This early colonial history concludes that matters of citizenship, secularism, and national identity—which remain so contentious in France today—can only be understood by looking at the colonial past through a new and broadened lens.