St. Leo the Great became Pope in 440, at a time of political instability and serious disputes over Christian teaching. Through his preaching and writing, he became one of the most influential popes of the early Church and was later named a Doctor of the Church.

Leo played an important role in defending the Church’s teaching about the person of Christ and was closely connected with the Council of Chalcedon. He is also remembered for meeting Attila the Hun in 452 as his forces threatened Italy. His leadership during a turbulent age helped strengthen both the unity of the Church and the role of the Bishop of Rome.