Complex sentence: They become a guerrilla group, with Freeman as the secret leader, and set out to ensure that black people truly live freely within the United States by partaking in both violent and non-violent actions throughout Chicago.
Split into simpler sentences: They become a guerrilla group with Freeman as the secret leader. The Freedom Fighters set out to ensure that black people truly live freely within the United States by partaking in both violent and non-violent actions throughout Chicago.