|Saint Gildas de Rhuys, en France.|
The historical Gildas was a Welsh monk, author of a somewhat more forgiving Rule than that of Saint David. I'll confess that I don't know how David's Rule stacks up against Benedict's, but I would tend to favor a little elasticity in monastic rules, if I had to live under one. Irish monks crossed the sea to learn from Gildas, which is high praise as the sixth century Irish monastic tradition was no small thing.
This same Gildas, author of De Excidio et Conquestu Britanniae (On the Ruin and Conquest of Britain), blamed the faithlessness of the British people. Just as Jeremiah (to whom Gildas is often compared) told the Hebrews that the Babylonian Captivity was their own fault for not following the laws of God, Gildas told the Brits that the Anglo-Saxons were swarming across Britain because they (the British) had failed the Lord. It's called tough love.
A saint named Gildas, perhaps the same guy or maybe another one, lived as a hermit in Brittany (France). He/They are celebrated on January 29.
Gildas, who stood in judgment of late antiquity British kings like Aurelius Conanus and Maelgwn, was apparently helpful to King Arthur. King Melwas abducted Arthur's wife, Guinevere, at some point, which ought to have triggered a civil war among Britons. Civil war was the last thing they needed during the Anglo-Saxon-Jute invasion, so Gildas negotiated the Queen's release and a reconciliation between the kings. Sadly, Gildas' brother was less helpful to the King. Huail ap Caw led a rebellion against Arthur and was beheaded by him. The execution stone is preserved in the Welsh town of Ruthin. Perhaps this is why Arthur is not mentioned in Gidas' extant writings, even though they were contemporaries.