Celestine I was born in the Campania and served as a deacon under Innocent I. Elected pope in 422, Celestine confiscated the property of Novationite churches and restored a basilica in St Mary Travestere after it had been damaged in Alaric’s sack of Rome. Although Celestine confirmed the appointment of Nestorius to the see of Constantinople, the pope opposed Nestorius’ teachings and supported Cyril of Alexandria in the conflict between the two patriarchs. Celestine also combatted Pelagianism and semi-Pelagianism in southtern Gaul and in England. He was the founder of the papal diplomatic service. He is supposed to have sent Palladius to evangelise Ireland in 431. Celestine died in 432 and was buried in the cemetery of Priscilla. – Catholic Online