Saint Mamertus – Saint Mamertus (died c. 475) was the bishop of Vienne in Gaul, venerated as a saint. His primary contribution to ecclesiastical practice was the introduction of litanies prior to Ascension Day as an intercession against earthquakes and other disasters, leading to “Rogation Days.” His feast day is the first of the Ice Saints.

Mamertus – Wikipedia

https://en.wikipedia.org/wiki/Mamertus

Saint Mamertus (died c. 475) was the bishop of Vienne in Gaul, venerated as a saint. His primary contribution to ecclesiastical practice was the introduction of litanies prior to Ascension Day as an intercession against earthquakes and other disasters, leading to “Rogation Days.” His feast day is the first of the Ice Saints.