Calatrava La Vieja (Old Calatrava), an ancient city of La Mancha, Spain, now in ruins, on the Guadiana, 12 m. N. E. of Ciudad Real. The city was in the middle ages one of the keys of the Sierra Morena, and was strongly fortified. In 1158, being menaced by the Moors, it was abandoned by the templars, who had held it for 10 years, and the king, Sancho III., promised it to any one who would hold it. Raymond, abbot of Fitero, and Diego Velasquez undertook the task. A crusade was proclaimed, and plenary indulgences were promised to all who should take part in its defence. The Moors abandoned the siege, and Velasquez made inroads into their territories. The order of Calatrava was then founded, consisting of two classes, one for the field, the other for the choir. The knights subsequently separated from the monks, and chose a grand master, while the monks returned to their abbey at Fitero. The knights acquired renown and riches in their contests with the Moors, but in the end quarrelled among themselves, and the pope in 1523 adjudged the grand-mastership to the crown in perpetuity.

In 1808 the great possessions of the order were confiscated, and it became simply an order of merit.