Illtud the Knight was the son of a little-known Breton Prince named Bican. His mother was Lady Rhieinwylydd, daughter of Prince Amlawdd Wledig and sister of High-Queen Ygerna. These parents sent him, as a young lad, to learn the ways of the church, apparently under his great-uncle, St. Garmon (later Bishop of Manaw). Though an excellent pupil, particularly in the area of literature, he had other ideas for his future career and turned his training, instead, to the military.
Having learnt the ways of chivalric pursuits, Illtud travelled to Britain to seek out his cousin, the High-King Arthur. He was given a fine welcome at the Royal British Court and stayed there for some time in the King's service. He even met and married his wife, Trynihid, there. Later, however, he was offered a position in the Royal Guard of King Pawl of Penychen. The couple moved to Nant Pawl in what is now Mid-Glamorgan and Illtud so impressed the King that he was soon made Master of the Royal Household.
Illtud's Royal Warband were an unruly lot and were wont to harass strangers in the kingdom. They once stole some food and drink from St. Cadog's monastery at Llancarfan, but were pursued by the monks and driven into a bog where the earth swallowed them up! Only Illtud survived. Cadog reminded him of his Christian upbringing and converted him back to his childhood religion.
Illtud then chose to leave his wife and become a monk in the Hodnant Valley. Here, with the help and encouragement of the Archbishop, St. Dyfrig, he built the monastery of Llanilltud Fawr (Llantwit Major). The local king, Merchwyn Wylt of Gorfynedd, was furious when he discovered him on his land but, eventually, he was so impressed by Illtud's piety that he let me stay. Illtud gathered around him many other monks and taught them the seven religious arts. Amongst his many pupils are said to have been SS. Samson, Pawl of Leon, Gildas, Dewi, Leonorius, Tudwal & Baglan.
Illtud's relationship with King Merchwyn Wylt continued to have its ups and downs. The King's steward harassed the saint and found himself melting before his fire. Merchwyn was so incensed that he drove Illtud from his monastery and he was forced to live in hiding in a cave on the banks of the Ewenny for a year and three days. His underground oratory was only discovered when, one day, a messenger from St. Gildas passed by with the gift of a bell for St. Dewi. The bell sounded and the monks of Llanilltud Fawr were able to bring their Abbot back into the fold.
Later, a second Royal Steward opposed Illtud and found himself swallowed up by a marsh. King Merchwyn and his men arrived at Llanilltud to exact revenge but soon suffered the same fate! The Abbot then found it politique to retire to a cave in Llwynarth where he lived for three years.
Eventually Illtud returned to Llanilltud Abbey. He set the year's harvest in order, threshed and stored in granaries, and then decided to visit his childhood home in Brittany. While abroad, he saw the Breton poor starving and had his abbey's whole crop transported across the Channel to feed them. Some say that Illtud died in Brittany and was buried at St. Samson's monastery at Dol, though his relics were, naturally, also claimed by Llanilltud Fawr. His feast day is 6th November.