In this classic of the revolutionary film category, Gillo Pontecorvo tells the story of Sir William Walker, played with narcissistic panache by Marlon Brando, an adventurer and soldier of fortune hired by the British Government to foment revolution by Portugese slaves on the island of Queimada in the Antilles, and 10 years later, by the sugar planters to supress those same slaves, notably in the person of their leader, José Dolores (Evaristo Marquez).
Brando, who at this time was well known for his support for radical politics, including the Black Power movement in the US, had approached Pontecorvo, famous for his previous film, The Battle Of Algiers (1966) with the project and the latter obliged with the assistance of writers, Franco Solinas and Giorgio Arioro. The result is a potent anti-colonialist, anti-establishmentarian story but also one of betrayal and self-betrayal in which Brando is ably matched by Marquez, who apparently had never seen a film, let alone acted in one, before this, as his sometime puppet and eventual nemesis. Despite the temper of the times, the film failed commercially.
Production-wise it's fairly rough and ready and very much if its time (the opening title sequence is outstanding in this respect) There is more than a hint of Sergio Leone's mythicising style evident but this adds to the film's appeal although not everyone will say the same of Brando's peculiar English accent or his mannered acting.
FYI: The film comes in various shorter running times but 132m was the original release For a very different version of the same story see Alex Cox's Walker.