In December 1915, United States Industrial Alcohol (USIA) built—without any formal engineering design—a massive cylindrical steel tank along Boston’s North End waterfront to store incoming shipments of molasses. When the tank ruptured three years later, 21 people died. USIA immediately blamed the rupture on an anarchist bomb attack, but a three-year legal battle pointed elsewhere. Explore the phenomena of metal fatigue and brittle fracture and learn what role they played in the Great Boston Molasses Flood.