Unlike the contemporary orders of Calatrava and Alcántara, which followed the severe rule of the Benedictines of Cîteaux, Santiago adopted the milder rule of the Canons of St. Augustine. At León, they offered their services to the Canons Regular of Saint Eligius in that town for the protection of pilgrims to the shrine of St. James and the hospices on the roads leading to Compostela. This explains the mixed character of their order—hospitaller and military—like that of St. John of Jerusalem. They were recognized as religious by Pope Alexander III, whose Bull of 5 July 1175, was subsequently confirmed by more than twenty of his successors. These pontifical acts, collected in the "Bullarium" of the order, secured them all the privileges and exemptions of other monastic orders. The order comprised several affiliated classes: canons, charged with the administration of the sacraments; canonesses, occupied with the service of pilgrims; religious knights living in community, and married knights. The right to marry, which other military orders only obtained at the end of the Middle Ages, was accorded them from the beginning under certain conditions, such as the authorization of the king, the obligation of observing continence during Advent, Lent, and on certain festivals of the year, which they spent at their monasteries in retreat.