The Constant Principle

In 1437, the Portuguese prince Don Fernando is taken prisoner by the Sultan of Morocco after an unsuccessful military expedition. In exchange for his freedom, the prince is ordered by the Sultan to destroy the town of Ceuta, a Catholic stronghold in North Africa. Prince Fernando decides that his life is not worth such a concession. He prefers life as a slave in a Muslim prison.

Fernando died in 1443. He was made a saint by the Catholic Church, and his heroic deed was glorified, in part, becoming the subject of Calderon's philosophical drama, ‘The Constant Prince’ (El Principe constant, 1629).