Salvatore Maranzano was a Mafioso of the Prohibition era and leader of a group known as "Moustache Petes," many of whom were former members of the Sicilian Mafia. Maranzano was born in Castellammare del Golfo, on the island of Sicily and educated in the local seminary. After World War I, he moved to the United States and became a protege of Don Vito Cascio Ferro, the Boss of Bosses of the Sicilian Mafia.

In the United States, under the command of Joe "the Boss"Masseria, Maranzano was determined to build his own empire. He put together an organization of Sicilians with ventures in bootlegging, gambling, and other illegal activity, which was headed by Castellammare-born Mafiosi. The killing that became known as the Castellammarese War began in February of 1930 when Gaetano Reina, a top aide to Masseria, was shot to death, allegedly the first victim of Maranzano. By April of 1931, dozens of men had been killed as the battle raged through the streets of New York. The homicides included the killing of Joseph Catania, a top aide of Joe "the Boss" Masseria, and ultimately concluded with the murder of Masseria himself on April 15, 1931.

Maranzano then attempted to establish himself as the capo di tutti capi ("boss of all the bosses"). Under Maranzano's plan, each mob, or "family," would be reorganized with both a boss and an underboss and each family was supposed to respect the interests and territories of the others. Disputes were supposed to be arbitrated, rather than settled with violence. This system was adopted by the Five Families of New York City and by many other Italian mobs across the United States. Maranzano's reign was short-lived, however. The same men who helped him rise to power, also plotted to kill him. On the September 10, 1931, four men posing as police officers walked into an office building in Manhattan and shot and stabbed Salvatore Maranzano to death. The four men escaped, and no one was ever charged with the murder.