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The Sunken City of Ys
A tragic column about folklore and tabletop RPGs
Long ago, on the coast of Brittany, there was once a beautiful and rich city. But, due to devilry and sin, it was swallowed by the sea and condemned to myth. Now only the shadow of the city lives on beneath the waves.
This is the legend of the once-great city of Ys.
The City of Ys
The story of the City of Ys has many versions, but all end in tragedy. Also known as Is or Kêr-Is (“Low City”) in Breton, and Ville d'Ys in French, this mythic city is said to have resided on the far coast of what was then the Kingdom of Brittany.
Our story has three constant characters:
King Gradlon the Great (“Gralon Meur” in Breton), a pious, saintly, and semi-legendary king;
Dahut (also Dahud, Ahè, Ahès), his wayward daughter. Later versions give her mother as Malgven, the magical and potentially fey “Queen of the North”.
If we take either Saints’ inclusion at face value, we can place our story either during or at the end of the fifth century—though the story itself likely originates closer to the fifteenth century.
Over a millennia ago, Ys stood proudly on the coast of Brittany, rich in both the arts and commerce. From his palace of marble, cedar, and gold, the city was ruled by the pious King Gradlon. Built beside the sea, Ys was protected from flooding by a dyke. To allow in ships during low tide, however, a gate was built into the wall. It had only one key, held by the king.
Dahut, the king’s daughter, was frivolous at best, an unrepentant sinner at worst (or even a sorceress, like her mother). She ultimately spells Ys’ doom, when—to allow her lover inside the city, or at the persuasion of a devil in disguise—she steals the key from her father. Drunk and under the cover of darkness, she mistakenly opens the dyke gate rather than the city gates. The sea sweeps in, submerging the city.
Only one person survives: King Gradlon, woken by St. Gwenole and urged to flee. The king mounts his horse and takes his daughter with him, but they cannot outrun the water. As the sea is about to overtake them, however, a voice calls out:
"Throw the demon thou carriest into the sea, if thou dost not desire to perish."
Dahut falls, or is thrown, from the horse, and King Gradlon is saved.
Other versions of the Ys story frame it even more starkly as a morality tale. In these, the whole city has fallen, absorbed in luxury, debauchery, and vanity, despite the king’s pious nature. God decides he must punish Ys and warns St. Gwenole before he does. The Saint rushes to warn King Gradlon, who then flees the city on horseback. Much like Atlantis before it, a divine storm falls upon the city and the sea rises to swallow it. As always, Gradlon tries to save Dahut, but at the voice’s urging, he once again throws her from his horse.
This religious angle fits with the 1888 opera Le roi d'Ys, where Dahut (here Princess Margared) must sacrifice herself to stop the rising tides. If you need a larger cast of characters for your Ys, this version of the tale introduces:
Rozenn, Margared’s younger sister;
Mylio, a knight of Ys. Presumed dead in a shipwreck, both sisters vie for his love upon his return;
and Prince Karnac, Ys’ enemy. He is engaged to Margared to secure a peace treaty, but she breaks it off after learning Mylio is still alive.
When Rozenn becomes betrothed to Mylio, a jealous Margared conspires with Karnac by giving him the keys to the city’s flood gates. She is immediately filled with regret, however, and rushes to her sister’s wedding to warn her father. Mylio slays Karnac, but not before he opens the gates. As the city drowns, Margared realises she must sacrifice herself, and in doing so, summons the spirit of St Corentin to calm the waves and save the city.
Though King Gradlon survives Ys’ sinking, his story essentially ends here. He retires to the town of Quimper, where a statue dedicated to him was erected at the cathedral. It remains there to this day.
Dahut, on the other hand, is often said to have been transformed into a siren-like mermaid or morgen (water spirit), left to haunt the sea above the ruins of Ys:
“Fisherman, have you seen the daughter of the sea combing her golden hair in the midday sun at the fringes of the beach?” “Yes,” replies the fisherman, “I have seen the white daughter of the sea, and I have heard her sing, and her songs were plaintive as the sound of the waves.”
Most variations on the legend place Ys in the Baie de Douarnenez, a bay in the far west of France. If one is to visit the right place in the bay at low tide, you might even see the ruins of Ys—or hear, at least, the sounds of its carillon from beneath the waves.
Using Ys in Your Game
It might sometimes feel like a piece of folklore like Ys is of limited use, too specific as is. In these scenarios though, never forget that these tales are inspiration first and foremost. All stories, especially folklore, are infinitely mutable. You can always take what you learned here and use it to make something entirely unique to you.
Here are a couple of ways Ys can inspire your fantasy game.
Pre-ruin Ys: On your map is a wealthy and influential coastal city. All manner of goods can be bought here—or sold, if the PCs are seeking a buyer for a particularly unusual piece of loot. A festival is on and the city is vivacious. The locals say there’s a celebration almost every week these days. If they’re influential or well-known, perhaps the PCs are invited to the palace. Once there, will they recognise the princess’ knightly suitor is actually a demon-in-disguise in time?
Ruined Ys: On your map is a set of sunken ruins, located just off the coast. The nearest fishing village speaks of a legendary city that sinned and was drowned as punishment. Upon visiting its location, the PCs can see the remains of stone buildings beneath the waves. The locals are threatened by a murderous water spirit; ‘Dahut’ is the tale they tell to explain it.
A Dream Vacation
Every PC deserves a vacation, especially to somewhere as beautiful as the coast of France. And what better place than the historic seaside town of Kêr-Is? Most of the town is a hold over from when it was a medieval city, and the streets are filled with people excited for the upcoming festival. It’s a city of light, love, and luxurious celebration.
Don’t mind that things seem slightly off, the colours both too vibrant and too dull. Don’t mind that only a few people have actually spoken to you, that the locals’ ways are unusual and out-of-date. Don’t mind the storm clouds building on the horizon, the strange tension in the air. Don’t mind that your first proper memory of this place was waking up in your hotel room, not of travelling and arriving here. And, of course, don’t mind that, no matter what you do, you can’t seem to leave.
Looking at the story of Ys through a modern lens, it’s not hard to look at how Gradlon treated his daughter as kinda messed up. Not only that but can we really take Ys as a den of sin and then also say “But it’s king? Great guy, super pious. Shame he was powerless to even try doing anything about how everyone behaved in the city he ruled.”
Maybe all that is the reason why people still hear the sunken city’s bells, why Dahut lingers on as a vengeful water spirit. In this framing, King Gradlon made the wrong call and cursed Ys as a result. Perhaps the voice Gradlon heard wasn’t God at all, but the same devil who tricked Dahut into flooding the city, now tricking her father so it can claim one more victim. Or, more simply, the voice could have been a test, a suggestion a supposedly good and pious man like Gradlon should have rejected.
If Gradlon’s sacrifice of his daughter was a damning mistake, then the PCs can take it upon themselves to fix things and let the souls of Ys finally rest. They might even be asked by Dahut or the ghosts of Ys to do so after experiencing the city through the Dream Vacation prompt above. Or maybe an angelic being enlists the PCs to break the curse and free their spirits from the demon that tricked them.
To release Ys, Gradlon is the key. His bones need to be found, graverobbed, and brought to the beach to invoke his spirit so it can talk with Dahut. Or maybe Gradlon was cursed by his actions and still lives, a lonely, immortal old man. To twist the knife further, he could confess that he lied when he told people the story of Ys. There was no voice at all. In that moment, full of rage and anguish, he threw down his daughter of his own accord.
Dahut as a Morgen Statistics (Old-School)
Armor Class: 5 
Hit Dice: 4* (18 hp)
Attacks: 1 x weapon (1d6 or by weapon), 1 x hypnotic voice (charm)
THAC0: 16 [+3]
Move: 120’ (40’) / 180’ (60’) swimming
Save As: Fighter 7
▶ Charm: Dahut can infuse her voice with hypnotic magic, causing those who hear it to save versus spells or be charmed: move towards her (resisting those who try to prevent it); obey her commands (if understood); defend her; unable to cast spells or use magic items; unable to harm her. A character who saves is unaffected for the rest of the encounter. Killing Dahut breaks the charm; otherwise, she can voluntarily end it.
▶ Curse: Once per day. Save versus spells or be afflicted by a curse (Dahut’s choosing, but not greater effect than: –2 penalty to saves, –4 penalty to hit, an ability score reduced by 50%).
▶ Hydrokinesis: While in or near a body of water, Dahut can telekinetically manipulate it as a weapon [1d8, Melee, Missile (5’–20’ / 21’–40’ / 41’–60’)].
▶ Magic Resistance: +2 bonus to all saving throws against magic.
Dahut can make her curses conditional, only functioning under specific circumstances (such as if someone acts against her, or if they detour from a specific quest she has given them). She can also lift any curse she inflicts.
And that’s it for the City of Ys! Next time you visit the beach, make sure to remember the first thing they teach you in swimming lessons: never swim toward a naked, singing lady.
Thanks for reading! Make sure to come back next week for another fantastical piece of folklore to use in your role-playing games.
Penny for your thoughts: Have you ever had a sunken city in one of your games before? What brought about its destruction?
~ A.C. Luke
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Spence, Lewis. 2010. Legends & Romances of Brittany. Frederick A. Stokes Company: Edinburgh.
Doan, James. 1981. "The Legend of the Sunken City in Welsh and Breton Tradition". Folklore 92.1: 77–83.
Spence, Lewis. 2010. Legends & Romances of Brittany. Frederick A. Stokes Company: Edinburgh.