The First Lateran Council was the 9th ecumenical council of the Catholic Church, convened by Pope Callixtus II in 1123, opened on 18 March 1123 in Rome at the Lateran Palace. And about 300 bishops and 600 abbots attended, making it the largest church council up to that point. Held shortly after the Concordat of Worms (1122), which ended the long-running Investiture Controversy between the papacy and the Holy Roman Emperors over who had the right to appoint bishops and abbots, it confirmed the Concordat of Worms, asserting the Church’s independence from secular rulers in appointing clergy. Additionally it issued canons against simony (the buying and selling of church offices), prohibited clerical marriage and enforced celibacy among priests, and declared protection for church property and people traveling to Rome (such as pilgrims and clergy).

As such it set important precedents by strengthening papal authority and reinforcing the separation between spiritual and temporal power.