Gerin, Gerins, Geryn
The ruler of Chartres under King Arthur.
He brought the Twelve Peers of the Gauls to Arthur’s coronation in Caerleon, and later brought soldiers to accompany Arthur in his campaign against Rome. He was one of the three messengers that Arthur sent to meet with the Roman Emperor Lucius – an effort that resulted in ruin when Gawain killed a Roman warrior.
Guerin fought for Arthur throughout the Roman campaign, and was a key player at the final battle at Soissons.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century