He instituted in his diocese the fasts and supplications called the Rogations, on the following occasions. Almighty God, to punish the sins of the people, visited them with wars and other public calamities, and awaked them from their spiritual lethargy by the terrors of earthquakes, fires, and ravenous wild beasts, which last were sometimes seen in the very market-place of cities. These evils the impious ascribed to blind chance; but religious and prudent persons considered them as tokens of the divine anger, which threatened their entire destruction. Amidst these scourges, St. Mammertus received a token of the divine mercy. A terrible fire happened in the city of Vienne, which baffled the efforts of men; but by the prayers of the good bishop the fire on a sudden went out. This miracle strongly affected the minds of the people. The holy prelate took this opportunity to make them sensible of the necessity and efficacy of devout prayer, and formed a pious design of instituting an annual fast and supplication of three days, in which all the faithful should join, with sincere compunction of heart, to appease the divine indignation by fasting, prayer, tears, and the confession of sins. The Church of Auvergne, of which St. Sidonius was bishop, adopted this pious institution before the year 475, and it became in a very short time a universal practice. St. Mammertus died about the year 477.
Feast Day of Saint Mammertus
The Feast Day of Saint Mammertus is May 11. The origin of Feast Days: most saints have specially designated feast days and are associated with a specific day of the year and these are referred to as the saint's feast day. The feast days first arose from the very early Christian custom of the annual commemoration of martyrs on the dates of their deaths at the same time celebrating their birth into heaven.