Saint Derfel's day

 April 5 is the day associated with this saint. From the wiki

Reputedly born around 566, Derfel is said to be one of seven warriors of Arthur who survived the Battle of Camlan.^[1] Three of the six other survivors were also said to have become saints. While others survived through good fortune, Derfel survived "by his strength alone".

Derfel is said to have been a noted warrior in medieval Welsh poetry. Tudur Penllyn wrote:

Derfel mewn rhyfel, gwnai'i wayw'n rhyfedd, Darrisg dur yw'r wisg, dewr yw'r osgedd.

("Derfel in war, he would work his spear wondrously, steel covering is the garment, brave is the appearance.")

According to Lewys Glyn Cothi:

"When there were at Camlan men and fighting and a host being slain, Derfel with his arms was dividing steel there in two".

After Camlan, Derfel is unanimously held in Welsh tradition to have entered the religious life. After a possible stint as a wandering hermit,^[1] he is said to have entered the monastery of Llantwit. He was also associated with Llandderfel in Gwynedd, named after and said to have founded by him. He is also said to have served as the abbot of Ynys Enlli, Bardsey Island, succeeding his cousin St. Cadfan. He is said to have died of natural causes on 6 April 660.