Religious order of Spanish knighthood, founded in 1156 as the Knights of Saint Julian de Pereiro, for defense against the Moors. It became a religious society in 1176, received papal recognition as a military order in 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 in 1540. In 1808 the revenues were confiscated. Since 1875 the title has been conferred by the king for military services.