Largely forgotten now, Frankie Yale was an influential New York mobster of the early 20th century whose proteges included future leaders of New York's five Mafia families and Chicago's outfit. His influence extended to Chicago, where he personally committed two of the city's most notorious underworld assassinations and waged a five-year war to wrest control of Brooklyn's docks from Irish rivals. His murder marked New York City's first use of a Tommy gun in gangland warfare, the same weapon used in Chicago's St. Valentine's Day massacre seven months later. Yale's passing destabilized Gotham's Mafia, paving the way for an upheaval that modified and modernized the structure of American syndicated crime for the next six decades. Despite Yale's prominence during his life, this is the first biography to survey his life and career.