The Order of Calatrava is a medieval military order founded in 1158 in Spain. It was established to protect Christian territories from Muslim forces during the Reconquista, a period of conflict aimed at reclaiming the Iberian Peninsula. The order is named after the Calatrava castle, which became its headquarters. Members of the Order of Calatrava took vows of chastity, poverty, and obedience, similar to monastic orders. They played a significant role in various battles and were known for their distinctive white robes adorned with a red cross. The order eventually became influential in both military and political affairs in Spain.