Marines from 6th Marine Corps District attended the Phi Beta Sigma Conclave, a historically black fraternity, in an effort to reach out to members of the African American community. The Marine Corps is currently stepping up its efforts to recruit a more diverse selection of officers to lead Marines. - Marines from 6th Marine Corps District attended the Phi Beta Sigma Conclave, a historically black fraternity, in an effort to reach out to members of the African American community. The Marine Corps is currently stepping up its efforts to recruit a more diverse selection of officers to lead Marines.