Mob Boss Files: Dean O'Banion

Dean O’Banion was the sharp-dressed, hot-tempered leader of the North Side Gang in 1920s Chicago.

A florist by day and bootlegger by night, O’Banion built a powerful Irish-American syndicate that clashed violently with Al Capone’s South Side Italian mob.

His assassination in 1924 inside his flower shop sparked a bloody gang war that reshaped the Chicago underworld.

O’Banion’s death marked the rise of Capone — and the beginning of the end for Irish dominance in organized crime.