Earthquakes and other calamities afflicted the diocese of Vienna in Dauphine (France) in the fifth century, and St. Mamertus, who was bishop of that diocese, instituted a penitential procession with public supplications on the Monday, Tuesday and Wednesday before Ascension Day. In 816 Pope Leo III introduced it into Rome and soon after it became a general observance throughout the Church. The Litany of Saints, the psalms and prayers sung during the procession on these days are supplications: hence the same of Rogation Days (rogare, to ask) applied to them. The object of the "rogation" supplications is to appease the anger of God and avert the scourges of His justice, and to pray for the harvest.