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Mamertus
Bishop of Vienne
SaintResearchedPre-congregation
Feast: 11 May (not on the universal Roman calendar; kept in the Roman Martyrology or local calendars)
Born
400
Died
475
verified
Beatified
—
not needed: before formal processes
Canonised
By tradition
recognised before formal processes began
Who they were
Mamertus, of a wealthy family near Lyons and learned in secular and sacred subjects, became Bishop of Vienne shortly before 462 and ordained his brother Claudianus, a monk, as his priest.
He was the founder of the Rogation processions. He died soon after 475 and was venerated as a saint.
The miracles
There was never a formal cause: he has been honoured as a saint since before the Church's formal processes began.
Why that counted as sanctity
A learned bishop of Vienne.
Sources
- Catholic Encyclopedia (1913), via New Advent - St. Mamertus
- Wikidata Q1335921 — dates, feast day and identifiers (CC0)
- English Wikipedia — Mamertus (CC BY-SA)
Checked against the sources listed on 21 September 2026. Corrections welcome.