St. Illtud was popular among the very ancient Celts, but there are few dependable sources about his life story.
A seventh-century life of St. Samson of Brittany, France, is the first to make mention of him. Its author says that Illtud was a brilliant disciple of St. Germain, the noted bishop of Auxerre, in north central France, who also ordained him to the priesthood.
Whether Illtud was a native of Brittany in France or a Briton from Wales is obscure. The first biography of Illtud himself, written around 1140, represents him as the son of a prominent Briton, and a cousin of the famous King Arthur. This untrustworthy account says that as a young man he married a lady named Trynihid, and became a soldier in Wales. Hence he is sometimes referred to as “Illtud the Knight.” But shocked by the hunting death of a friend, he was inspired to leave his wife and become a hermit. (A matrimonial detail, which, like the accounts of a number of his miracles, is dubious.)
What is certain is that Illtud helped pioneer the monastic life in Wales by founding a monastery at what is now Llantwit Major in Glamorgan, the southernmost county in Wales. This became the first great Welsh monastic school. Taught there, besides theology, were the Scriptures, philosophy, poetry and rhetoric, grammar and arithmetic. Abbot Illtud was also a master of the manual arts. In keeping with the monastic tradition of agriculture, he developed and taught to his monks and to farmers in general an improved method of plowing.
It is related that when there was a famine in French Brittany, Abbot Illtud organized a fleet of boats to carry grain to the hungry Bretons. This sounds very plausible, especially since there are many churches and places named after him in Brittany.
One legend says that in his old age, St. Illtud went back yet again to Armorican (French) Brittany, whose people are, of course, Celts closely linked with the Celtic Britons and the Welsh. There, the narrator asserts, the Abbot died at Dol (a town that figured, we will recall, in the famous “D-Day” invasion of World War II). It seems more likely, however, that he died at Llantwit in Wales. The life of Samson says so; and a ninth-century cross at Llantwit bears the names of “Iltet, Samson and Ebisar.”
One medieval Welsh document names Illtud, in his knightly days, as one of the triumvirate (the others were named Cadoc and Peredur) to whom King Arthur gave custody of the Holy Grail. On this basis, some scholars have tried to identify Knight Illtud with Sir Galahad. But here we move into the mists of Camelot, where there is more fancy than fact.
It is sufficient for us to know, for certain, that St. Illtud was a bright, charitable monastic leader, deeply revered and today still remembered for his holiness among the Celts of Wales and of Armorica.
–Father Robert F. McNamara