Caliban’s slave status has most often been attributed to either his racial identity or the practice of colonialism. This essay argues instead that Shakespeare clearly attributes his enslavement to a specific act—the attempted rape of Miranda. Under the jus gentium, this assault constituted an act of private war, in which Caliban was conquered by Prospero, who acquired absolute mastery over Caliban’s person with the right to either kill or enslave him. This process is repeated when Ferdinand commits an act of war by drawing his sword against Prospero. Like Caliban, he is defeated and enslaved, as the play makes clear when he is ordered to stack logs, the same menial task performed by his putative rival for Miranda. To work through the trauma of sexual assault upon which the history of the island is founded, Ferdinand must repeat Caliban’s actions under Prospero’s supervision and control. The parallel between the two men who seek to possess Miranda sexually also draws attention to the relationship established in the play between Europe and Africa, which is developed in both the marriage of Claribel to the King of Tunis and Prospero’s rivalry with Sycorax.