Greg Grandin in The Chronicle of Higher Education:
Benito Cereno is one of the bleakest pieces of writing in American literature. Published in installments in late 1855, midway between the commercial and critical failure of Moby-Dick and the start of the Civil War, the novella reads like a devil's edition of Harriet Beecher Stowe's Uncle Tom's Cabin,which had appeared a few years earlier. Where Stowe made her case for abolition by presenting Southern slaves as Christlike innocents and martyrs, Melville's West Africans are ruthless and deceitful. They act like Toms—but they are really Nat Turners. “Who aint a slave?” Melville had Ishmael ask in 1851's Moby-Dick. There's joy in the question, as well as in the implied answer—no one—an acceptance of the fact that humans, by sheer dint of being human, are bound to one another. Four years closer to the Civil War, Melville might have had that question in mind again when he wrote Benito Cereno. The answer would have been the same, yet the implications grimmer. There were no free people on board the Tryal (named San Dominick in the novella). Obviously not Cereno, held hostage by the West Africans. Not Babo and the rest of the rebels, forced to mimic their own enslavement and humiliation. And not Amasa Delano, locked in the soft cell of his own blindness.
Most of Benito Cereno takes place in the fictional Delano's mind. Page after page is devoted to his reveries, and readers experience the day on board the ship—which was filled with odd rituals, cryptic comments, peculiar symbols—as he experiences it. Melville keeps secret, just as it was kept secret from Delano, the fact that the slaves are running things. And like the real Delano, Melville's version is transfixed by the Spanish captain's relationship to his black slave.
More here.