An unprecedented language crisis unfolded in the heart of the town of Saint-Leonard in 1968-1969. French-speaking parents demanded French-only schools, while members of the Italian community wanted to preserve bilingual schools. The conflict spread throughout Quebec, creating enormous tensions that degenerated into violence and culminated in a bloody riot. The Battle of Saint-Leonard tells the story of Raymond Lemieux and Mario Barone, two remarkable yet forgotten men of modest origins, who each fought with strength and conviction, despite the heavy consequences to themselves, their families, and their professional lives. Their struggle changed the destiny of Quebec.