Gradlon

Gradlon is a legendary king of Cornouaille, a historical region in Brittany, France. He is a prominent figure in Arthurian legend and Breton folklore, particularly associated with the city of Ys. According to legend, Ys was a magnificent city built below sea level, protected by a dike and a gate that was opened only by the king's key. Gradlon is often depicted as a just and wise ruler who ruled his kingdom with fairness.

The most famous story involving Gradlon concerns the destruction of Ys. It is said that his daughter, Dahut, a sorceress or a siren, either stole the key and opened the gate in a fit of defiance or encouraged a storm to break the dike. Regardless of the exact cause, the sea flooded the city, drowning its inhabitants. Gradlon, however, was saved, often by Saint Guénolé. In some versions of the legend, Gradlon is condemned to wander eternally as a phantom or is forced to relive the destruction of his city.

The legend of King Gradlon and the city of Ys serves as a cautionary tale about pride, disobedience, and the consequences of unchecked power or desire. It reflects the historical anxieties of coastal communities facing the threat of the sea and has been retold and adapted in various forms of literature and art over centuries, solidifying Gradlon's place in the rich tapestry of Breton mythology.