Guerrilla theatre is a form of theatrical protest popularised in America in the 1960s by the San Fransisco Mime Troupe. Commedia dell’Arte and satire were actually the group’s principal modes of performance, not mime. At its purest, guerrilla theatre was left-wing political activism in the form of avant-garde theatre performed in non-traditional spaces such as public parks and sidewalks. – Justin Cash
Academic thesis by Angela Rothman “Revolutionary Theatricality: Dramatized American Protest, 1967-1968” includes a detailed investigation of the San Fransisco Mime Troupe and other guerrilla theatre groups.