The Columbia Encyclopedia, Sixth Edition. 2001-07.
Carlos, prince of the Asturias
154568, prince of the Asturias, son of Philip II of Spain and Maria of Portugal. Don Carlos, who seems to have been mentally unbalanced and subject to fits of homicidal mania, was imprisoned by his father in 1568. When he died shortly afterward, it was rumored (falsely) that Philip had poisoned him. Friedrich von Schiller deliberately idealized his character in his tragedy Don Carlos, portraying him as a champion of liberalism, unhappily in love with his stepmother, Elizabeth of Valois.