When the United States passed the 18th amendment in 1920 banning the manufacture, importation and sale of alcoholic beverages, it immediately created a lucrative black market to serve the millions of Americans who had no intention of giving up booze.

Organized crime groups filled the void. They either smuggled in alcohol from Canada and other countries or they made it themselves. They typically sold these illicit spirits in underground bars and nightclubs, or speakeasies, which flourished in cities across the country.

Bootlegging, as this new industry became known, was a highly profitable enterprise that turned street hoodlums into millionaires. With so much money at stake, competition was fierce, and nowhere more so than in Chicago, the capital of bootlegging during the 1920s. Turf wars erupted, and rivals frequently hijacked each other’s alcohol shipments. Dueling gangs equipped with Thompson submachine guns often resorted to violence to solve conflicts.

Al Capone’s South Side Gang emerged as a dominant force in Chicago bootlegging, but Capone’s desire to control the whole city — really the entire upper Midwest — was constantly being challenged. A persistent thorn in Capone’s side was George “Bugs” Moran’s North Side Gang.