Archbishop of Vienne
Saint Mammertus, Archbishop of Vienne in Dauphiné during the 5th century, was a prelate renowned for his sanctity, learning, and miracles. He instituted in his diocese the fasts and supplications called the Rogations, during the three days before the Ascension, to remedy the neglect of religion which brought down on ancient Gaul many chastisements.
Almighty God, to punish the sins of the people, had visited them with wars and other public calamities and awakened the city of Vienne in particular from spiritual lethargy by the terrors of earthquakes, fires, and ravenous wild beasts, which were sometimes seen in the very market place. These evils were ascribed by the impious to blind chance, but religious and prudent persons considered them as tokens of the divine anger, which threatened their entire destruction.
Amid these scourges, Saint Mammertus received a pledge of the divine mercy. A terrible fire broke out on Easter night in the city of Vienne, which baffled the efforts of men; but by the prayers of the good bishop the fire suddenly went out. This miracle strongly affected the minds of the people. It was on this occasion that the holy prelate conceived the project of restoring the Rogations, which had fallen into oblivion. The Church of Auvergne, where Saint Sidonius Apollonarius was bishop of Clermont, also adopted this pious institution before the year 475, and in a very short time it became a universal practice. His pious reform was received by all the churches of France after the first Council of Orleans under Clovis the Great, and then by the Church of Rome under the authority of Leo III.
Saint Mammertus died about the year 477 in Vienne, but his body was transported to Orleans and placed in its cathedral. There, until the 16th century, it remained in great veneration, then was burnt by enemies of the Church.