Frank Capone with mobster John Torrio. By 1918, Torrio had moved to Chicago to help a relative defend his rackets, and Torrio soon asked Al and later Frank to join him there. By 1920, Torrio had taken charge of the South Side Gang and the Prohibition era had started. As the gang increased in power and wealth, so did Al and Frank. In 1923, Chicago voters elected a new mayor, William Dever, who proceeded to crack down on Torrio, the Capone brothers, and their South Side Gang. In response, Torrio tasked Al with creating speakeasies, brothels, and illegal gambling dens in Cicero,
Al Capone suspected of being involved. Torrio headed an essentially Italian organized crime group that was the biggest in the city, with Capone as his right-hand man. He was wary of being drawn into gang wars and tried to negotiate agreements over territory between rival crime groups. The smaller North Side Gang led by Dean O'Banion (also known as Dion O'Banion) was of mixed ethnicity, and it came under pressure from the Genna brothers who were allied with Torrio. O'Banion found that Torrio was unhelpful with the encroachment of the Gennas into the North Side, despite his pretensions to be a settler