St. Illtud was popular but there are very few sources about his actual life. It is believed to have been born around 540. According to some accounts, he was the disciple of Bishop Germanus of Auxerre in France. Illtud was a great scholar who had studied the scriptures of the Old and New Testaments. He had also studied philosophy, geometry, rhetoric, grammar, and arithmetic. He was an educated Briton living shortly after Rome’s departure.
It was also believed he was the son of a Breton prince and a cousin of King Arthur. His parents wanted him to be a priest or monk. They had him educated in literature for this reason. He soon gave up his religious upbringing, deciding instead to pursue a military career. He married a wife named Trynihid and became a soldier in Wales. First, he served King Arthur, and then King Poulentus. This is why he is called St. Illtud the Knight. One afternoon, he was with a hunting party who sent a message to the abbot. The group demanded the abbot feed them. The abbot found them to be very rude and improper but graciously offered them a meal anyway. Before they could enjoy the meal, the ground opened up and swallowed the whole party as just punishment for their impiety. Only Illtud was spared. He went to St. Cadog, begging forgiveness for his sins. The abbot told him to quit being selfish. He should go back to his religious upbringing. Illtud gave up his wife, and became a hermit.
Illtud helped pioneer the monastic life of Wales. He founded a monastery at Llantwit Major. This became the first major Welsh monastic school. Some students were believed to be Saint Patrick, Paul Aurelian, Taliesin, Gildas, and Samson of Dol. Saint David is also believed to have spent some time there.