Among the first pieces completed were the two Prigioni (renamed the "slaves" only in the nineteenth century), destined for the lower part of the funerary monument, next to the pilasters which framed the niches containing the Victories.

The date of the two statues is confirmed by a letter of Michelangelo to Marcello dei Covi, in which he speaks of a viewing by Luca Signorelli in his Roman house, while he worked on "a figure of marble, standing four cubits high, which has its hands behind its back".

In 1632 they were sold by Henri II de Montmorency to Cardinal Richelieu, who had them sent to his Château in Poitou, where they were seen by Gianlorenzo Bernini who made an illustration of them, on his travels.

The "Rebellious Slave" is portrayed trying to free himself from the fetters which hold his hands behind his back, contorting his torso and twisting his head.

The iconographic significance of the two figures is probably linked to the motif of the Captive in Roman art; in fact Giorgio Vasari identified them as personifications of the provinces controlled by Julius II.