Caer Dathyl, also called Caerdathyl, is the seat and habitual dwelling of Math son of Mathonwy in Arvon. It serves both as the center of his rule over Gwynedd and as the setting for the private assault on Goewin that turns Gwydion and Gilvaethwy’s misconduct into a matter Math must judge.

Setting and Court

Math dwells continually at Caer Dathyl and cannot make the circuit of the land. His nephews Gwydion and Gilvaethwy, with members of his household, travel through Gwynedd in his stead. The court’s daily arrangement is shaped by Math’s dependence on a maiden’s lap: except when war prevents it, he can exist only with his feet resting in a maiden’s lap. Goewin, daughter of Pebin of Dol Pebin in Arvon and described as the fairest maiden of her time there, attends him continually.

A Return to the Stronghold

After Gwydion’s men bring the pigs they have obtained through deception into Gwynedd, they proceed to Math at Caer Dathyl. The country is already rising against them: Pryderi is assembling the forces of the twenty-one Cantrefs to pursue them. Once the host is heard approaching, Math and his men arm and march to Penardd, leaving the stronghold as the conflict shifts into open battle. After Pryderi is killed and the men of Gwynedd return in triumph, Math goes back to Caer Dathyl.

The Chamber and Its Consequences

At Caer Dathyl, Gilvaethwy returns at night with Gwydion and takes Math’s couch. He drives the other maidens from the room and forces Goewin to remain against her will. The following day the brothers rejoin Math and his host, so the assault is not disclosed to him until after the fighting and Pryderi’s death. On Math’s return to his chamber, Goewin tells him she is now a wife because of the attack and names Gwydion and Gilvaethwy as those who wronged her and dishonored Math. Math promises her compensation, takes her as his wife, and gives her possession of his dominions. The stronghold thus becomes the point where a concealed abuse is made public and addressed as both an injury to Goewin and a dishonor to the ruler.