Saint David (Welsh: Dewi Sant) was born towards the end of the 5th century. He was a scion of the royal house of Ceredigion, and founded a Celtic monastic community at Glyn Rhosyn (The Vale of Roses) on the western headland of Pembrokeshire (Welsh: Sir Benfro) at the spot where St David's Cathedral stands today.
David's fame as a teacher and his asceticism spread among Celtic Christians. His foundation at Glyn Rhosin became an important Christian shrine, and the most important centre in Wales. The date of Saint David's death is recorded as 1 March, but the year is uncertain – possibly 601. As his tearful monks prepared for his death Saint David uttered these words: "Brothers be ye constant. The yoke which with single mind ye have taken, bear ye to the end; and whatsoever ye have seen with me and heard, keep and fulfil."
For centuries, 1 March has been a national festival. Saint David was recognised as a national patron saint at the height of Welsh resistance to the Normans. Saint David's Day was celebrated by Welsh diaspora from the late Middle Ages. Indeed, the 17th-century diarist Samuel Pepys noted how Welsh celebrations in London for Saint David's Day would spark wider countercelebrations amongst their English neighbours: life-sized effigies of Welshmen were symbolically lynched, and by the 18th century the custom had arisen of confectioners producing "taffies"—gingerbread figures baked in the shape of a Welshman riding a goat—on Saint David's Day.
Saint David's Day is not a national holiday in the United Kingdom. Similarly in the United States, it has regularly been celebrated, although it is not an official holiday. It is invariably celebrated by Welsh societies throughout the world with dinners, parties, and eisteddfodau (recitals and concerts).
In the poem Armes Prydein (The Prophesy of Britain), composed in the early to mid-tenth century, the anonymous author prophesies that the Cymry (the Welsh people) will unite and join an alliance of fellow-Celts to repel the Anglo-Saxons, under the banner of Saint David: A lluman glân Dewi a ddyrchafant (And they will raise the pure banner of Dewi). Although there were periodic Welsh uprisings in the Middle Ages, the country was briefly united by various Welsh princes before its conquest at different times and it arguably had a very short period of independence during the rising of Owain Glyndwr, but Wales as a whole never experienced a long period as an independent kingdom. Henry Tudor, 2nd Earl of Richmond, who was born in Pembroke Castle and a patrilineal descendant of the Tudor Dynasty of North Wales, became King Henry VII of England after his victory over Richard III at the Battle of Bosworth Field in 1485 to end the Wars of the Roses. Henry's green and white banner with a red dragon, became a rallying cause of Welsh patriotism behind the memory of Saint David on his Feast Day. Henry was the first monarch of the House of Tudor, and during the reign of that dynasty, the royal coat of arms included the Welsh Dragon, a reference to the monarch's origin. The banner from Henry's victory was not adapted to become the official Flag of Wales until 1959. However, the flag of Saint David is a golden cross on a black background and was not part of the symbolism of House of Tudor.
Source - Wikipedia
Image Credit - “Welsh flag, St David's flag, St David's Day / Baner Cymru, Baner Dewi Sant, Dydd Gŵyl Dewi 2009” by National Assembly for Wales is licensed under CC BY 2.0