 One group known as the Hamburg Athletic Club, whose members included a 17-year-old Richard J. Daley, future mayor of Chicago, contributed to gang violence in the area.Longstanding racial tensions between whites and blacks exploded in five days of violence that started on July 27, 1919.On that hot summer day, on a segregated Chicago beach, a group of white men stoned Eugene Williams to death when he crossed the unofficial barrier between the white and black sections of the 29th Street beach.