On 31 May 1881, at Pouilly-le-Fort, Pasteur carried out the first controlled, public vaccine trial in history before an audience of journalists, veterinarians, and skeptics. Twenty-five sheep vaccinated with attenuated anthrax bacillus survived; twenty-five unvaccinated ones died. The experiment turned vaccination from a scientific curiosity into a medical technology verifiable before civil society. It was also the consolidation of the principle of attenuation — formulated two years earlier with fowl cholera — as a reproducible platform for bacterial diseases.