King Sebastian of Portugal, 1554–1578
King of Portugal from 1557–1578, Sebastian (Portuguese Sebastião) was the grandson and successor to John III. Succeeding to the throne at the age of three, Sebastian reigned under the regency of first his grandmother (to 1562) and then of his uncle Henry (later king himself) until he came of age in 1568.
A weak and sickly child, Sebastian was educated from a young age by Jesuit monks, who imbued him with a fanatical religious fervor. By the time he came of age, Sebastian had come to think of himself as a latter-day crusader and desperately wanted to undertake a holy crusade against muslim infidels. To Sebastian's warped mind, an appeal for help from a pretender to the Moroccan throne in 1576 seemed the perfect opportunity.
Sebastian immediately began preparing for an expedition to Morocco, spending enormous sums to hire and outfit an army of foreign mercenaries. Finally ready in 1578, Sebastian and his army landed in Morocco, where he was promptly crushed at the Battle of Ksar el Kebir. Both Sebastian and the pretender, Muhammad, died in the fighting, which also claimed the life of the legitimate Moroccan king Abd al-Malik.
At the time however, after the chaos of the battle, nobody was sure if Sebastian was dead or not. A rumor emerged that he had been captured. A strange legend developed that one day Sebastian would return to Portugal, and the messiananic cult that grew around this legend, Sebastianism, produced several Sebastian pretenders and lasted into the 19th century!
Sebastian was succeeded by his uncle Henry, who turned out to be the last of the Aviz dynasty. The crown then devolved to Philip II of Spain, and Spanish control of Portugal began.