Religious order of Spanish knighthood, founded, 1156, as the Knights of Saint Julian de Pereiro, for defense against the Moors. It became a religious society, 1176, received papal recognition as a military order, 1197, and in 1218 united with the Knights of Calatrava, accepting from them the Cistercian rule and costume, and adopting the name, Knights of Alcantara. The order acquired great wealth and power, resulting in internal dissension. The knights were released from the vow of celibacy, 1540. In 1808 the revenues were confiscated. Since 1875 the title has been conferred by the king for military services.