This saint flourished in the sixth century. He was a prince in
Wales, which he left in his youth, and retired into Armorica to live
a recluse. He stopt at the isle of Groie, which is about a league
from the mouth of the Blavet. Grallon was then lord of the isle, and
was so edified at his conversation, that he bestowed on him, for
founding a monastery, the land between the confluence of the river
Isol and Ellé. For which reason even to this day, the abbey is called
Kemperle, which in the old British language signifies the conflux of
Ellé. One year that a prodigious swarm of insects devoured the corn,
Guerech I., count of Vannes, dreading a famine, deputed three persons
of quality to engage the saint’s prayers to God for turning away
the scourge. Gunthiern sent him water which he had blessed, which
he desired to be sprinkled over the fields, and the insects were
destroyed. The count, in gratitude for this extraordinary blessing,
gave him the land near the river Blavet, which was then called
Vernac; but is now known by the name of Hervegnac or Chervegnac.
The saint, it is thought, died at Kemperle. During the incursions
of the Normans, his body was concealed in the isle of Groie. It was
discovered in the eleventh century, and brought to the monastery
of Kemperle,[21] which now belongs to the Benedictine Order. St.
Gunthiern is patron of this abbey as well as of many other churches
and chapels in Brittany. He is mentioned in ancient calendars on the
29th of June, but the moderns place his feast on the 3d of July. See
Lobineau, Vies des SS. de Bretagne, p. 49.