SEBASTIAN, king of Portugal (Port. Sebastião) (1554–1578), the posthumous son of Prince John of Portugal and of his wife Joanna, daughter of the emperor Charles, was born in 1554, and became king in 1557, on the death of his grandfather John III. of Portugal. During his minority (1557–1568), his grandmother Queen Catherine and his great uncle the Cardinal Prince Henry acted jointly as regents. Sebastian’s education was entrusted to a Jesuit, D. Luiz Conçalves da Camara and to D. Aleixo de Menezes, a veteran who had served under Albuquerque. He grew up resolved to emulate the medieval knights who had reconquered Portugal from the Moors. He was a mystic and a fanatic, whose sole ambition was to lead a crusade against the Mahommedans in north-west Africa. He entrusted the government to the Jesuits; refused either to summon the Cortes or to marry, although the Portuguese crown would otherwise pass to a foreigner, and devoted himself wholly to hunting, martial exercises and the severest forms of asceticism. His first expedition to Morocco, in 1574, was little more than a reconnaissance; in a second expedition Sebastian was killed and his army annihilated at Al Kasr al Kebir (4th of August 1578). Although his body was identified before burial at Al Kasr, reinterred at Ceuta, and thence (1582) removed by Philip II. of Spain to the Convento dos Jeronymos in Lisbon, many Portuguese refused to credit his death. “Sebastianism” became a religion. Its votaries believed that the rei encuberto, or “hidden king,” was either absent on a pilgrimage, or, like King Arthur in Avalon, was awaiting the hour of his second advent in some enchanted island. Four pretenders to the throne successively impersonated Sebastian; the first two, known from their places of birth as the “King of Penamacor” and the “King of Ericeira,” were of peasant origin; they were captured in 1584 and 1585 respectively. The third, Gabriel Espinosa, was a man of some education, whose adherents included members of the Austrian and Spanish courts and of the Society of Jesus in Portugal. He was executed in 1594. The fourth was a Calabrian named Marco Tullio, who knew no Portuguese; he impersonated the “hidden king” at Venice in 1603 and gained many supporters, but was ultimately captured and executed. The Sebastianists had an important share in the Portuguese insurrection of 1640, and were again prominent during the Miguelite wars (1828–34). At an even later period Sir R. F. Burton stated that he had met with Sebastianists in remote parts of Brazil (Burton, Camoens, vol. i.p. 363, London, 1881), and the cult appears to have survived until the beginning of the 20th century, although it ceased to be a political force after 1834.
See Portugal, History; J. Barbosa Machado, Memorias para . . . . . o governo del rey D. Sebastião (4 vols., Lisbon, 1736–1741); Miguel d’Antas, Les Faux Don Sébastien (Paris, 1866); São Mamede, Don Sébastien et Philippe II (Paris, 1884).